JP4368368B2 - Manufacturing method of glass lump, manufacturing apparatus thereof, and manufacturing method of optical element - Google Patents
Manufacturing method of glass lump, manufacturing apparatus thereof, and manufacturing method of optical element Download PDFInfo
- Publication number
- JP4368368B2 JP4368368B2 JP2006213113A JP2006213113A JP4368368B2 JP 4368368 B2 JP4368368 B2 JP 4368368B2 JP 2006213113 A JP2006213113 A JP 2006213113A JP 2006213113 A JP2006213113 A JP 2006213113A JP 4368368 B2 JP4368368 B2 JP 4368368B2
- Authority
- JP
- Japan
- Prior art keywords
- press
- glass lump
- molten glass
- mold
- lower mold
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Re-Forming, After-Treatment, Cutting And Transporting Of Glass Products (AREA)
- Glass Compositions (AREA)
Description
本発明は、ガラス塊の製造方法、その製造装置および光学素子の製造方法に関する。さらに詳しくは、本発明は、精密プレス成形用プリフォームなどとして用いられるガラス塊を寸法精度よく、高い生産性のもとで製造する方法、この方法に用いられるガラス塊の製造装置、および該ガラス塊を精密プレス成形して光学素子を製造する方法に関するものである。 The present invention relates to a glass lump manufacturing method, a manufacturing apparatus thereof, and an optical element manufacturing method. More specifically, the present invention relates to a method for producing a glass lump used as a precision press-molding preform or the like with high dimensional accuracy and high productivity, a glass lump manufacturing apparatus used in this method, and the glass The present invention relates to a method of manufacturing an optical element by precision press molding a lump.
デジタルカメラ等の光学機器では、機器のコンパクト化のために高屈折率レンズを採用することが多い。特に高屈折率な非球面化レンズは、光学系のコンパクト化や高性能化への寄与が大きく待望されている。しかしながら、高屈折率な光学ガラスは一般に軟化点が高いため、プレス温度が高くなり、プレス装置の耐久性やレンズの成形精度等で問題が発生しやすい。また精密プレスレンズとしては、成形が容易で精度を得やすい凸レンズが多く製造されてきたが、最近では凹メニスレンズや両凹レンズといった、成形が難しく成形精度が得られにくい精密プレスレンズが増えてきた。 In an optical device such as a digital camera, a high refractive index lens is often used to make the device compact. In particular, an aspherical lens having a high refractive index is highly expected to contribute to compactness and high performance of the optical system. However, since optical glass having a high refractive index generally has a high softening point, the press temperature becomes high, and problems are likely to occur in terms of durability of the press device, molding accuracy of the lens, and the like. As precision press lenses, many convex lenses that are easy to mold and easy to obtain have been manufactured. Recently, however, there are an increasing number of precision press lenses that are difficult to mold and difficult to obtain, such as concave meniscus lenses and biconcave lenses.
具体的には、高屈折率（高軟化点）光学ガラスは、プレス温度が高いため、プレス型や離型膜の耐久性に問題が発生し、プレスできなくなったり、離型膜劣化により、連続成形可能数が減少したり、プレス機構の熱膨張の影響で成形精度（偏芯など）が悪化するなど、好ましくない事態を招来する。対策としてはプリフォーム形状をレンズ形状に近づけてプレス時の変形量を減らし、プレス温度を低くする方法が有効である。 Specifically, high refractive index (high softening point) optical glass has a high press temperature, which causes problems with the durability of the press mold and release film. This leads to an undesirable situation such as a decrease in the number of moldable products and deterioration of molding accuracy (eccentricity, etc.) due to the thermal expansion of the press mechanism. As a countermeasure, it is effective to reduce the amount of deformation during pressing by bringing the preform shape closer to the lens shape and lowering the pressing temperature.
一方、難形状レンズにおいては、凹メニスレンズの場合、上型が凸状でアールが小さいため、プリフォーム上面のアールが小さいとプレス時に上型とプリフォームの中心がずれやすく、成形レンズが偏肉し成形精度が悪化する。対策としては、プリフォーム上面中央のアールを大きくするか又は平面化する方法が有効である。また、両凹レンズの場合、上下型とも凸状でアールが小さいので、プリフォーム下面のアールが小さいと下型の上に安定してプリフォームを固定すること自体が難しい。加えて、凹メニスレンズと同様に、プリフォーム上面のアールが小さいと上型とプリフォームの中心がずれやすい。対策としては、下型上で安定して保持しかつプレス時の偏芯を抑制するため、プリフォーム上下面のアールを大きくする（又は平面化する）。 On the other hand, in a difficult-to-shape lens, in the case of a concave meniscus, the upper mold is convex and the radius is small. However, the molding accuracy deteriorates. As a countermeasure, a method of increasing or flattening the radius at the center of the upper surface of the preform is effective. In the case of a biconcave lens, both the upper and lower molds are convex and have a small radius, so if the radius on the lower surface of the preform is small, it is difficult to stably fix the preform on the lower mold. In addition, as with the concave menis lens, if the radius of the upper surface of the preform is small, the center of the upper mold and the preform are liable to shift. As a countermeasure, in order to hold stably on the lower mold and suppress eccentricity during pressing, the upper and lower surfaces of the preform are rounded (or flattened).
以上のように、精密プレスレンズの高屈折率化や難形状化により、装置の耐久性や成形精度に問題が発生しやすくなり、その対策としてプリフォームの薄肉化や平板化、そして近似形状化が求められるようになった。 As mentioned above, the high refractive index and the difficult shape of precision press lenses are likely to cause problems in the durability and molding accuracy of the equipment. Is now required.
これらの要求に対しては、ガラスブロックを円板状に加工し両面研磨したプリフォームや、球面レンズの加工法により作製した近似形状化プリフォームが使われている。しかしながら、これらの場合、熱間成形によるプリフォームと較べて著しくコスト高になるのを免れない。 In order to meet these requirements, a preform obtained by processing a glass block into a disk shape and polishing on both sides, or an approximately shaped preform manufactured by a spherical lens processing method is used. However, in these cases, it is inevitable that the cost is significantly higher than a preform formed by hot forming.
以下に、プリフォームの熱間成形法にプレス成形技術を加え、プリフォーム形状を制御する従来例とその問題点について説明する。
（１）上下型：多孔質（非接触状態でプレスし冷却）
多孔質部材からなる凹部成形面を有する下型を用い、成形面から高圧ガスを噴き出した状態で溶融ガラス塊を浮上保持し、冷却過程で同様な構造の上型で溶融ガラスをプレスして溶融ガラスを成形型の形状に変形させ、溶融ガラスと型の界面にガスクッションを形成
しながら非接触状態で冷却し、薄肉、又は近似形状の光学ガラス素子を成形する方法が開示されている（例えば、特許文献１参照）。しかしながら、この方法においては、以下に示すような問題がある。
A conventional example of adding a press molding technique to the preform hot forming method to control the preform shape and its problems will be described below.
(1) Upper and lower molds: porous (pressed and cooled in a non-contact state)
Using a lower mold with a concave molding surface made of a porous material, the molten glass lump is levitated and held in a state where high pressure gas is ejected from the molding surface, and the molten glass is pressed and melted with an upper mold of the same structure during the cooling process. Disclosed is a method of deforming glass into a mold shape, cooling in a non-contact state while forming a gas cushion at the interface between the molten glass and the mold, and molding a thin-walled or approximate-shaped optical glass element (for example, , See Patent Document 1). However, this method has the following problems.
多孔質型のガスクッションで包まれた溶融ガラス塊は非接触状態となるため、溶融ガラス塊の内部と表面部（特に外周部）で大きな温度分布ができる傾向がある。そのために、溶融ガラス中央部の硬化が遅れヒケが発生しやすい。上記発明では、多孔質型から高温に加熱したガスを噴出させ溶融ガラス内の温度分布を縮小している。しかし、この方法では、溶融ガラスの冷却速度が著しく低下するので、成形時間が長くなり、成形能率が悪くなるという問題がある。また多孔質型から噴き出すガス温度を高めるには、多孔質型自体の温度も同程度まで加熱する必要があり、溶融ガラスのキャスト時などに溶融ガラスが型に融着する危険性が高まる。その他、成形工程において、成形型や噴出ガスの温度を連続的に変化させながら制御する必要があり、かつプレス速度やプレス量（厚み）を連続的に変化させながら長時間連続的にプレスする必要がある。その結果として製造装置が複雑化し、成形装置のコストが高くなるという問題がある。 Since the molten glass lump wrapped with the porous gas cushion is in a non-contact state, there is a tendency that a large temperature distribution can be generated in the interior and surface portion (particularly the outer peripheral portion) of the molten glass lump. Therefore, hardening of the molten glass center part is delayed and sink marks are likely to occur. In the above invention, the gas heated to a high temperature is ejected from the porous mold to reduce the temperature distribution in the molten glass. However, this method has a problem that the cooling rate of the molten glass is remarkably lowered, so that the molding time becomes long and the molding efficiency is deteriorated. In order to increase the temperature of the gas ejected from the porous mold, the temperature of the porous mold itself needs to be heated to the same level, which increases the risk of the molten glass being fused to the mold when the molten glass is cast. In addition, in the molding process, it is necessary to control while continuously changing the temperature of the mold and the jet gas, and it is necessary to press continuously for a long time while continuously changing the press speed and press amount (thickness). There is. As a result, there is a problem that the manufacturing apparatus becomes complicated and the cost of the molding apparatus increases.
（２）下型：マルチ穴、上型：緻密型
凹部成形面に衛星状に形成した細孔からガスを噴出させながら成形面にガラスを受け、溶融ガラスを浮上させながら冷却する過程で、緻密質上型でプレスしてプリフォーム上面を成形する方法が知られている。しかしながら、この方法では、ゴブの内部と外周部の温度差が大きくなるため、扁平に近いゴブの成形では、ゴブ下面中央にヒケが発生しやすい。また溶融ガラス塊の温度が急激に低下する過程でプレス成形するため、プレスの条件出しが難しい。その他、複数の成形型を循環使用してプレス成形する場合には、型毎に形状がばらつく問題がある。また下型上で浮上し揺動している溶融ガラスをプレスするため、偏肉したプレス品が得られやすい。
(2) Lower mold: multi-hole, upper mold: dense mold In the process of receiving glass on the molding surface while blowing gas from the pores formed in the shape of satellites on the concave molding surface and cooling it while floating the molten glass, A method of forming the upper surface of a preform by pressing with a quality die is known. However, in this method, the temperature difference between the inside and the outer periphery of the gob increases, and therefore, when forming a gob that is nearly flat, sink marks tend to occur at the center of the gob lower surface. Moreover, since press molding is performed in the process where the temperature of the molten glass lump sharply decreases, it is difficult to determine the press conditions. In addition, when press molding using a plurality of molding dies in circulation, there is a problem that the shape varies from one die to another. In addition, since the molten glass that floats and swings on the lower mold is pressed, an unevenly pressed product is easily obtained.
（３）下型：マルチ穴、上型：多孔質型
上記（２）と同様な下型で溶融ガラス塊を浮上させ、冷却過程で多孔質材料からなる上型からガスを噴き出させた状態で溶融ガラス塊の上面をプレス成形する方法が知られている。この方法は、上型構造を除き上記（２）と同一である。したがって上記（２）と同様の問題が起こる。その他、上型によるプレスが非接触で行われるため、プレス型との熱交換により溶融ガラスを冷却することができない。したがって、間欠的なプレス法では、停留時間内でプレス面形状を固定することが難しく、プレス型形状に近いプリフォームを得にくいという問題がある。
本発明は、このような事情のもとで、精密プレス成形用プリフォーム、例えば中心肉厚が薄く、直径／中心肉厚比が大きい薄肉のプリフォーム、片面のアールが大きいかまたはほぼ平面である薄肉のプリフォーム、両面アールが大きいかほぼ平面である薄肉のプリフォーム、片面が凹面である近似形状のプリフォームなどとして用いられるガラス塊を寸法精度よく、高い生産性のもとで製造する方法を提供することを目的とするものである。 Under such circumstances, the present invention is a precision press-molding preform, for example, a thin preform having a small center wall thickness and a large diameter / center wall thickness ratio. Manufacture glass ingots with high dimensional accuracy and high productivity for thin-walled preforms, thin-walled preforms that have large or almost flat surfaces on both sides, and approximate-shaped preforms that are concave on one side. It is intended to provide a method.
本発明者らは、前記目的を達成するために鋭意研究を重ねた結果、溶融ガラス塊を下型上で浮上させながら冷却してガラス塊を成形する工程において、特定の操作を施すことにより、その目的を達成し得ることを見出し、この知見に基づいて本発明を完成するに至った。 As a result of intensive studies to achieve the above-mentioned object, the present inventors performed a specific operation in the process of cooling the molten glass lump while floating on the lower mold to form the glass lump. It has been found that the object can be achieved, and the present invention has been completed based on this finding.
すなわち、本発明は、
（１） 流出パイプから流出する溶融ガラス流を下型で受け、ガラス流を切断して下型上に溶融ガラス塊を得、下型上で略浮上させながら冷却してガラス塊を成形する工程において、
下型上の溶融ガラス塊を上型に直接接触させた状態でプレスし、溶融ガラス塊の形状を固定後、プレス面に生じた表面のうねりを回復させ、自由表面化することを特徴とするガラス塊の製造方法、
（２） 初回のプレスを、溶融ガラス流を受け、キャスト直後から下型上で溶融ガラス塊の連続的な揺動が開始されるまでに行う上記（１）項に記載のガラス塊の製造方法、
（３） 溶融ガラス流を受け、キャスト直後から下型上で溶融ガラス塊の連続的な揺動が開始されるまでに、上型と下型を接近させ、上型により溶融ガラス塊の揺動を規制し、上下型と溶融ガラス塊の中心出しを行った後でプレスを開始する上記（１）項に記載のガラス塊の製造方法、
（４） プレス表面の自由表面化を、溶融ガラス塊内部からの熱伝導により行う上記（１）〜（３）項のいずれか１項に記載のガラス塊の製造方法、
（５） 溶融ガラス塊の熱量の放射を抑制する保温手段を用い、溶融ガラス内部からの熱伝導によるプレス面の自由表面化を補助する上記（１）〜（４）項のいずれか１項に記載のガラス塊の製造方法、
（６） プレス表面の自由表面化を、溶融ガラス塊内部からの熱伝導と外部からの加熱を組み合わせて行う上記（１）〜（５）項のいずれか１項に記載のガラス塊の製造方法、
（７） ガラス塊が精密プレス成形用プリフォームである上記（１）〜（６）項のいずれか１項に記載のガラス塊の製造方法、
（８） 複数の下型を流出ノズルに順番に供給し、連続的にキャスト、上型によるプレス成形、下型上での成形品の冷却、下型からの取り出しを繰り返すことによりガラス塊を製造するに際して、
上下型の内、少なくともどちらか一方を相対的に移動させ、上下型間の間隔を接近、離間させる駆動方式にＮＣ制御方式を用い、かつ下型毎にプレス成形時のプレス厚みを補正する上記（１）〜（７）項のいずれか１項に記載のガラス塊の製造方法、
（９） ガラス塊が精密プレス成形用プリフォームである上記（８）項に記載のガラス塊の製造方法、
（１０） 上記（７）又は（９）項に記載の方法によりガラス塊を製造し、得られたガラス塊を精密プレス成形することを特徴とする光学素子の製造方法、
を提供するものである。
That is, the present invention
(1) A process of receiving a molten glass flow flowing out from an outflow pipe with a lower mold, cutting the glass flow to obtain a molten glass lump on the lower mold, and cooling to form a glass lump while substantially floating on the lower mold. In
A glass characterized by pressing the molten glass lump on the lower mold in direct contact with the upper mold, fixing the shape of the molten glass lump, then recovering the swell of the surface generated on the pressing surface, and making it a free surface Lump manufacturing method,
(2) The method for producing a glass lump as described in the above item (1), wherein the first press is received from a molten glass flow and immediately after casting until the continuous oscillation of the molten glass lump is started on the lower mold. ,
(3) When the molten glass flow is received, the upper mold and the lower mold are brought close to each other from immediately after casting until the continuous oscillation of the molten glass lump starts on the lower mold, and the molten glass lump is swung by the upper mold. The method for producing a glass lump as described in (1) above, wherein the pressing is started after centering the upper and lower molds and the molten glass lump,
(4) The method for producing a glass lump according to any one of (1) to (3) above, wherein the press surface is made free surface by heat conduction from the inside of the molten glass lump.
(5) Any one of the above items (1) to (4), which uses a heat retaining means for suppressing radiation of the calorie of the molten glass lump and assists free surface formation of the press surface by heat conduction from the inside of the molten glass. A method for producing a glass lump of
(6) The method for producing a glass lump according to any one of (1) to (5) above, wherein free surface formation of the press surface is performed by combining heat conduction from the inside of the molten glass lump and heating from the outside.
(7) The method for producing a glass lump according to any one of (1) to (6) above, wherein the glass lump is a precision press-molding preform,
(8) Supply a plurality of lower molds sequentially to the outflow nozzle, and manufacture glass lump by repeating continuous casting, press molding with the upper mold, cooling of the molded product on the lower mold, and taking out from the lower mold When doing
The NC control method is used as a driving method for moving at least one of the upper and lower molds relatively so that the distance between the upper and lower molds approaches and separates, and the press thickness at the time of press molding is corrected for each lower mold. (1) The manufacturing method of the glass lump of any one of (7) term | claim,
(9) The method for producing a glass lump as described in (8) above, wherein the glass lump is a precision press-molding preform,
(10) (7) or (9) The method of manufacturing an optical element manufactured by Riga Las mass to the method described, characterized by precision press-molding the resulting glass gob to claim,
Is to provide.
本発明によれば、精密プレス成形用プリフォームなどとして用いられるガラス塊を寸法精度よく、高い生産性のもとで製造する方法、この方法に用いられるガラス塊の製造装置、および該ガラス塊を精密プレス成形して光学素子を製造する方法を提供することができる。 According to the present invention, a glass lump used as a precision press-molding preform or the like is manufactured with high dimensional accuracy and high productivity, a glass lump manufacturing apparatus used in this method, and the glass lump. A method of manufacturing an optical element by precision press molding can be provided.
まず、本発明のガラス塊の製造方法について説明する。
本発明のガラス塊の製造方法は、流出パイプから流出する溶融ガラス流を下型で受け、ガラス流を切断して下型上に溶融ガラス塊を得、下型上で略浮上させながら冷却してガラス塊を成形する工程において、下型上の溶融ガラス塊を上型に直接接触させた状態でプレスし、溶融ガラス塊の形状を固定後、プレス面に生じた表面のうねりを
回復させ、自由表面化することを特徴とする。
本発明は前記プレスを複数回行う態様（第１の態様という）と、前記プレスを１回のみ行う態様（第２の態様という）がある。なお、本願明細書では曲率半径のことをアールということがある。
First, the manufacturing method of the glass lump of this invention is demonstrated.
The method for producing a glass lump according to the present invention receives a molten glass flow flowing out from an outflow pipe with a lower mold, cuts the glass flow to obtain a molten glass lump on the lower mold, and cools while substantially floating on the lower mold. In the process of forming the glass lump, the molten glass lump on the lower mold is pressed in direct contact with the upper mold, the shape of the molten glass lump is fixed, and the surface undulation generated on the pressing surface is recovered, It is characterized by a free surface.
The present invention has an aspect in which the pressing is performed a plurality of times (referred to as a first aspect) and an aspect in which the pressing is performed only once (referred to as a second aspect). In the present specification, the radius of curvature is sometimes referred to as R.
第１の態様においては、以下に示す工程、すなわち任意工程であるプレス前工程、必須工程である予備プレス工程、本プレス工程、表面回復工程および任意工程である追加プレス工程を施すことにより、所望のガラス塊を得ることができる。 In the first aspect, a desired process is performed by performing the following steps, that is, a pre-pressing process that is an optional process, a preliminary pressing process that is an essential process, a main pressing process, a surface recovery process, and an additional pressing process that is an optional process. Can be obtained.
［プレス前工程］
この工程は、溶融ガラスと上型の位置合わせ、揺動の規制工程である。本工程は、任意工程であり、下型上で溶融ガラス塊の揺動が開始するまでに初回のプレスを行う場合は必要なく、初回のプレス開始を遅らせて溶融ガラス塊の揺動が開始した後にプレスを行う場合に有効な工程である。
当該プレス前工程においては、キャスト位置から退避直後の第２停留位置において（後述の図１、図２参照）、下型成形部で溶融ガラス塊の揺動が開始する以前に上型と下型を接近させて停止し、上型で溶融ガラス塊と上型の中心を合わせると共に溶融ガラスの揺動を規制する。
[Pre-press process]
This step is a step of regulating the alignment and swinging of the molten glass and the upper mold. This step is an optional step and is not necessary when the first press is performed before the start of rocking of the molten glass lump on the lower mold, and the rocking of the molten glass lump is started by delaying the first press start. This is an effective process when pressing later.
In the pre-pressing process, at the second stop position immediately after retraction from the casting position (see FIGS. 1 and 2 described later), the upper mold and the lower mold are moved before the molten glass lump starts to swing in the lower mold forming section. , And the center of the molten glass lump is aligned with the center of the upper mold and the oscillation of the molten glass is restricted.
具体的に説明すると、流出パイプから流出する溶融ガラス流を浮上成形が可能な下型に受けてキャストし、流出パイプ直下から退避した段階では、溶融ガラスの粘性が非常に低く、理想的な薄いガスクッションが溶融ガラスの下面に形成されている。そのためキャスト直後の段階では、下型内で溶融ガラス塊が揺動しない時間帯が存在する。もちろん流出パイプ直下から退避した直後は、慣性力で溶融ガラス塊が揺動するが、慣性による揺動は短時間で収まる。溶融ガラス塊下面の粘性が増大するに従い型とガラスの形状に差が生じ、溶融ガラス塊の揺動が始まる。本発明ではこのような現象に着目し、溶融ガラス塊の揺動開始前に溶融ガラス塊上に上型を接近させ、溶融ガラス塊の揺動を規制し上型と溶融ガラス塊の中心を合わせる。例えば上型が僅かでも凹面になっている場合は、容易に上型の中心に溶融ガラス塊を安定させることができる。但し、多孔質材料からなりガスを噴出している上型では、噴出ガスのため溶融ガラス塊の位置が不安定化しやすい。つまり溶融ガラス塊の位置を安定させるには、緻密質の上型が望ましい。上型の接近停止の際、上型と溶融ガラス塊は、僅かに接触させるか又はぎりぎり接触しない状態とする。なお上型が平面の場合は、僅かに接触させることで揺動を規制することができる。
上記溶融ガラス塊の揺動を規制することにより、得られるガラス塊の偏肉を防止することができる。
Specifically, when the molten glass flow flowing out from the outflow pipe is received and cast by a lower mold capable of flotation molding, and is retracted from directly under the outflow pipe, the viscosity of the molten glass is extremely low and ideally thin A gas cushion is formed on the lower surface of the molten glass. Therefore, at the stage immediately after casting, there is a time zone in which the molten glass lump does not swing in the lower mold. Of course, immediately after retreating from directly under the outflow pipe, the molten glass lump swings with inertial force, but the swing due to inertia is settled in a short time. As the viscosity of the lower surface of the molten glass lump increases, a difference occurs between the mold and the glass shape, and the molten glass lump starts to swing. In the present invention, paying attention to such a phenomenon, the upper mold is brought close to the molten glass lump before the molten glass lump starts swinging, and the swing of the molten glass lump is regulated so that the center of the upper mold and the molten glass lump is aligned. . For example, when the upper mold is slightly concave, the molten glass lump can be easily stabilized at the center of the upper mold. However, in the upper mold made of a porous material and ejecting gas, the position of the molten glass lump tends to become unstable due to the ejected gas. That is, a dense upper mold is desirable to stabilize the position of the molten glass block. When the upper mold approaches and stops, the upper mold and the molten glass lump are brought into contact with each other slightly or not in contact with each other. When the upper die is a flat surface, the swinging can be restricted by slightly contacting it.
By regulating the oscillation of the molten glass lump, uneven thickness of the obtained glass lump can be prevented.
［予備プレス工程］
この工程は、溶融ガラス塊中の温度分布の均一化工程である。
当該予備プレス工程においては、前記のプレス前工程後、タイミングを計り更に上下型を接近させ、溶融ガラス塊を所定時間プレスする。なお上型は溶融ガラスとの融着を防ぐため、風冷又は水冷等の手段で強制的に冷却しておく。所定時間プレス後は上下型を離間させ、溶融ガラス塊の形状を自然回復させる。なお上型の位置は、形状が自然回復した後の溶融ガラス塊の揺動を規制できる位置で保持することが望ましい。すなわち、形状が自然回復した後の溶融ガラス塊の上面が僅かに触れるか触れないかの位置に保持することが望ましい。
[Preliminary pressing process]
This step is a step of homogenizing the temperature distribution in the molten glass block.
In the preliminary pressing process, after the pre-pressing process, the timing is measured and the upper and lower molds are further approached, and the molten glass lump is pressed for a predetermined time. The upper mold is forcibly cooled by means such as air cooling or water cooling in order to prevent fusion with the molten glass. After pressing for a predetermined time, the upper and lower molds are separated to naturally recover the shape of the molten glass lump. The position of the upper mold is desirably held at a position where the swing of the molten glass lump after the natural recovery of the shape can be regulated. That is, it is desirable to hold the upper surface of the molten glass lump after the shape has been naturally recovered at a position where it slightly touches or does not touch.
具体的に説明すると、キャスト直後から、下型内の溶融ガラス塊内部には大きな温度分布が存在する。キャスト時に溶融ガラスが流下していた溶融ガラスの中央部は、外周部より格段に高温であるが、浮上冷却過程では更に温度分布が拡大する。これは溶融ガラス塊中央より外周の厚みが薄く冷えやすい上、揺動による下型との接触頻度が多いためと思われる。大きな温度分布が存在するままプレス成形すると、プレス品中央にヒケによる局部的な凹みができてしまう。 Specifically, a large temperature distribution exists in the molten glass block in the lower mold immediately after casting. The central portion of the molten glass from which the molten glass was flowing at the time of casting is much higher than the outer peripheral portion, but the temperature distribution is further expanded during the floating cooling process. This is probably because the outer peripheral thickness is thinner than the center of the molten glass lump and it is easy to cool, and the contact frequency with the lower mold due to rocking is high. If press molding is performed with a large temperature distribution, a local dent due to sink marks is formed in the center of the press product.
そこで第１の態様では、溶融ガラス塊内の温度分布を均一化する目的で予備プレスを行
う。低温の上型で短時間予備プレスすると、溶融ガラス上面側が冷却されるとともに、溶融ガラス中央側のガラスが外周側に移動する。この移動によりガラス塊の中央と外周で熱交換が起こる。また溶融ガラス下面側も、プレスにより下型と瞬間的に接触し冷却される。
Therefore, in the first aspect, preliminary pressing is performed for the purpose of making the temperature distribution in the molten glass block uniform. When preliminary pressing is performed for a short time with a low temperature upper mold, the upper surface side of the molten glass is cooled, and the glass at the center side of the molten glass moves to the outer peripheral side. This movement causes heat exchange between the center and the outer periphery of the glass lump. Also, the molten glass lower surface side is instantaneously brought into contact with the lower mold by the press and cooled.
なお予備プレスは短時間なので溶融ガラス塊の形状を固定するには至らず、プレス後は表面張力でプレス前の形状に戻ろうとする。この形状復帰の際、外側に移動したガラスが中央側に戻り、溶融ガラス塊の中央と外周の温度差が縮小する。またプレス面は最も温度低下が激しいが、形状回復時に溶融ガラス塊内部から熱をもらって加熱され、プレス面と内部の温度差が縮小する。一方、下型側の面も一時的に下型に触れて冷却されるが、予備プレス終了後は再び非接触状態となり、溶融ガラス塊内部の熱で加熱される。 Since the preliminary pressing is a short time, the shape of the molten glass lump cannot be fixed, and after pressing, the surface tension tries to return to the shape before pressing. At the time of this shape restoration, the glass moved to the outside returns to the center side, and the temperature difference between the center and the outer periphery of the molten glass lump is reduced. Further, the temperature of the press surface is most drastically lowered, but when the shape is recovered, heat is received from the inside of the molten glass lump and the temperature difference between the press surface and the inside is reduced. On the other hand, the surface on the lower mold side is also temporarily cooled by touching the lower mold, but after the preliminary pressing is finished, it is brought into a non-contact state again and is heated by the heat inside the molten glass lump.
以上のように、キャストから間もない溶融ガラス塊を低温の型で短時間予備プレスすることで、溶融ガラス上下面の冷却や、中央から外周への溶融ガラスの移動が起こる。予備プレス後は浮上状態となるため、形状回復とともに溶融ガラス内でのガラスの再移動や、冷却された上下表面と内部の熱交換が起こり、結果として溶融ガラス塊内部の温度分布が縮小する。 As described above, the molten glass lump that has just been cast is preliminarily pressed with a low temperature mold for a short time, thereby cooling the upper and lower surfaces of the molten glass and moving the molten glass from the center to the outer periphery. Since it becomes a floating state after the preliminary pressing, the glass re-moves in the molten glass and the heat exchange between the cooled upper and lower surfaces and the inside occurs along with the shape recovery, and as a result, the temperature distribution inside the molten glass lump is reduced.
予備プレス後の上型は、形状が自然回復した後の溶融ガラス塊の揺動を規制できる位置で保持することが望ましい。すなわち、溶融ガラス塊の上面が僅かに触れるか触れないかの位置に保持することが望ましい。この位置での保持により、予備プレス後の溶融ガラスと上型の中心が合った状態に保つことができ、同じ型で行う本プレスでの芯ずれを効果的に抑制することができる。またこの位置での保持により、上型が溶融ガラスで加熱されるため、本プレスでの冷却皺の発生を抑制することも可能になる。 It is desirable to hold the upper die after the preliminary pressing at a position where the swing of the molten glass lump after the natural recovery of the shape can be regulated. That is, it is desirable to hold at a position where the upper surface of the molten glass lump is slightly touched or not touched. By holding at this position, the center of the molten glass after the preliminary pressing and the center of the upper mold can be kept in alignment, and misalignment in the present press performed with the same mold can be effectively suppressed. Moreover, since the upper mold is heated by the molten glass by holding at this position, it becomes possible to suppress the generation of the cooling soot in the press.
［本プレス工程］
この工程は、溶融ガラスの全体形状の固定工程である。
当該本プレス工程においては、溶融ガラスを予備プレスと同じ上型で所定時間プレスする。本プレスでは、溶融ガラス塊の形状を変形させ固定することを目的とする。
具体的に説明すると、前記の予備プレスにより温度分布が均一化された溶融ガラス塊を、溶融ガラス塊上で保持した上型で再度プレスする。本プレスでのプレス時間は、プレス面の回復が生じる時間に調節する（長すぎると面回復が生じない）。本プレス直後のプレス面には軽微な冷却皺が生じるが、この表面の皺を次工程の表面回復工程で回復させる。
[This press process]
This step is a fixing step of the entire shape of the molten glass.
In the press process, the molten glass is pressed for a predetermined time with the same upper die as the preliminary press. The purpose of this press is to deform and fix the shape of the molten glass block.
More specifically, the molten glass lump whose temperature distribution has been made uniform by the preliminary pressing is pressed again with an upper mold held on the molten glass lump. The press time in this press is adjusted to the time when the recovery of the press surface occurs (the surface recovery does not occur if it is too long). A slight cooling flaw is generated on the press surface immediately after the press, and this surface flaw is recovered in the next surface recovery step.
［表面回復工程］
この工程はガラス塊表面の回復工程である。
強制冷却されている低温の上型でプレスしたプレス面には、プレス表面の急冷収縮による皺状の凸凹が発生する。但しこの皺状の凸凹は、プレス時間を加減することにより自然に自由表面に回復させることができる。つまり、プレスでの急激な温度低下が表面近傍に偏るため、プレス終了後は溶融ガラス内部の熱でプレス表面層が再加熱され自由表面化する。ガラス内部の熱量だけで自由表面化が困難な場合は、プレス面を外部から加熱することにより自由表面化することも可能である。
[Surface recovery process]
This process is a recovery process of the glass lump surface.
On the press surface pressed with a low-temperature upper die that is forcibly cooled, wrinkled irregularities are generated due to rapid shrinkage of the press surface. However, this bowl-shaped unevenness can be naturally recovered to a free surface by adjusting the pressing time. That is, since the rapid temperature drop in the press is biased to the vicinity of the surface, the press surface layer is reheated by the heat inside the molten glass after the press is completed, and becomes a free surface. When it is difficult to make a free surface only by the amount of heat inside the glass, it is also possible to make the free surface by heating the press surface from the outside.
具体的に説明すると、本プレス工程で生じた冷却皺（表面のうねり）は、溶融ガラスの表面層付近が急冷されることで生じる。したがって過度にプレス時間を長くしなければ、溶融ガラス内部の熱で表面層が加熱され自由表面化することができる。但し自由表面化といっても、自由表面と同等の表面品質である必要はなく、精密プレス成形に影響しない程度の凸凹やうねりが残っても問題はない。この表面回復の過程では、プレス面の成形精度、例えば中心厚み、プレス面のアール等も若干変化する。したがって、プレス後の若干の寸法変化を考慮して本プレス時のプレス厚みや上型のアールを決定することが望ましい。 If it demonstrates concretely, the cooling soot (surface waviness) which arose in this press process will arise when the surface layer vicinity of a molten glass is rapidly cooled. Therefore, unless the press time is excessively lengthened, the surface layer can be heated by the heat inside the molten glass to be free-surfaced. However, free surface formation does not need to have the same surface quality as the free surface, and there is no problem even if unevenness and waviness that do not affect precision press molding remain. In the process of surface recovery, the molding accuracy of the press surface, for example, the center thickness, the radius of the press surface and the like slightly change. Therefore, it is desirable to determine the press thickness and the upper die radius during the main press in consideration of slight dimensional changes after pressing.
一方、表面回復工程で生じる形状変化は、成形品の形状精度を悪化させる原因となることから、形状変化を最小限に抑制することが望ましい。そのため表面回復工程では、プレス面を上部から加熱し自由表面化を促進する方法や、保温により溶融ガラス塊の熱量損失を抑制し自由表面化を補助する方法を用いることもできる。本プレス工程後の溶融ガラス塊からの放熱を抑制し保温することにより、プレス表面の凸凹の自由表面化を促進することができる。具体的には、表面の放射率が低く厚み方向に断熱性を持たせたカップ状部材を下型上部にかぶせることにより、溶融ガラス塊からの放熱を抑制する。例えば表面研磨した０．３mm厚の白金やニッケル板を大小２種類のカップ状に加工し、小さいカップの外側を断熱材で覆い、その上に大きいカップを被せることにより、表面の放射率が小さく断熱性が良い保温用カップが得られる。なお断熱材を挿入するかわりに、カップ同士を溶接して二重容器とし、内部を真空にする方法でもよい。 On the other hand, since the shape change that occurs in the surface recovery process causes deterioration of the shape accuracy of the molded product, it is desirable to suppress the shape change to a minimum. Therefore, in the surface recovery step, it is possible to use a method of heating the press surface from above to promote free surface formation, or a method of assisting free surface formation by suppressing heat loss of the molten glass lump by keeping warm. By suppressing heat dissipation from the molten glass lump after the pressing step and keeping the temperature, it is possible to promote the free surface unevenness of the pressing surface. Specifically, the heat radiation from the molten glass lump is suppressed by covering the upper part of the lower mold with a cup-shaped member having a low surface emissivity and having heat insulation in the thickness direction. For example, surface-polished 0.3 mm thick platinum or nickel plate is processed into two types of large and small cups, the outer surface of the small cup is covered with a heat insulating material, and a large cup is placed on it to reduce the surface emissivity. A heat insulating cup with good heat insulation is obtained. Instead of inserting the heat insulating material, a method of welding the cups to form a double container and evacuating the inside may be used.
また、プレス面を上部から加熱する方法では、溶融ガラス内部の熱量で表面の自己回復が望めないほど硬化が進んだ場合でも、自由表面化が可能となる。そのため、自由表面化による寸法変化を最小限度に抑制することができる。またガラス表面側を輻射熱や高温ガスの吹き付け等により加熱すれば、表面回復時の形状変化を最小限度に抑えることができる。 Further, in the method of heating the press surface from the top, even when the curing progresses so that self-healing of the surface cannot be expected due to the amount of heat inside the molten glass, a free surface can be obtained. Therefore, dimensional changes due to free surface formation can be suppressed to a minimum. Moreover, if the glass surface side is heated by radiant heat, high temperature gas spraying, etc., the shape change at the time of surface recovery can be suppressed to the minimum.
［追加プレス工程］
この工程は、ガラス塊形状の再固定工程である。
当該追加プレス工程においては、本プレス工程で形状を固定しきれない場合（形状の戻りが大きい場合）に必要に応じ行うプレスである。このプレスでは予備プレスや本プレス工程で使用する低温の型ではなく、プレスしても冷却皺が発生しない温度まで加熱した上型を用いる。
[Additional press process]
This process is a glass block-shaped re-fixing process.
In the additional press step, the press is performed as necessary when the shape cannot be fixed in the present press step (when the shape is largely returned). In this press, an upper mold heated to a temperature at which no cooling soot is generated even when pressed is used, not a low-temperature mold used in the preliminary press or the main pressing process.
具体的に説明すると、成形品が大きい場合など、表面回復工程での形状変化が大きく、プレス面の形状精度が得られない場合に追加プレスを行う。追加プレス工程では、プレスで冷却皺が生じない程度に加熱した上型を使用し冷却皺を抑制する。なお前工程である本プレス工程で冷却皺が生じた場合は、この冷却皺の回復を待ってから追加プレスを行う。 More specifically, additional pressing is performed when the shape change in the surface recovery process is large and the shape accuracy of the press surface cannot be obtained, such as when the molded product is large. In the additional pressing process, the upper mold heated to such an extent that no cooling soot is generated by the press is used to suppress the cooling soot. In addition, when a cooling soot is generated in this press process, which is the previous process, additional press is performed after the cooling soot is recovered.
第２の態様は、予備プレス工程および追加プレス工程を経ずにガラス塊を製造する方法であり、任意工程であるプレス前工程、必須工程である本プレス工程、表面回復工程を有する。
第２の態様におけるプレス前工程の内容は上述した第１の態様におけるものと同様である。また、プレス前工程が任意工程である点も第１の態様と同様であり、下型上で溶融ガラス塊の揺動が開始するまでにプレスを行う場合は必要のない工程である。
本プレス工程、表面回復工程の内容も、上述した第１の態様におけるものと同様である。
上記第１の態様は、ガラス塊の下型に面する面（下面という）の中央にヒケによる窪みが生じる場合に採用することができるのに対して、第２の態様は、１回のプレスでもガラス塊の下面中央にヒケによる窪みが生じない場合に採用することができる。
上記第１の態様における予備プレス工程は、溶融ガラス中の温度分布を均一化する効果を有するため、ヒケの防止には極めて有効であるが、下面中央部のヒケが問題になるかどうかは、下型凹部の底面の曲率半径、下型温度、ガラスの流出速度、下型が同じであれば成形容積などの影響を大きく受け、具体的には、下型凹部の底面の曲率半径が大きいほど、下型温度が低いほど、成形容積が小さいほど、ガラスの流出速度が大きいほど、ガラス塊の下面中央部のヒケは大きくなる。従って、ガラス塊の下面中央部にヒケが生じないような場合には、第２の態様におけるように、必ずしも予備プレス成形を行う必要はない。
第２の態様はプレス回数が１回であるため、複数回プレスよりも条件パラメータが減り
、条件出しの時間を短縮化できる。また、第１の態様に比べ、下型（または上型）の上昇下降が１回で済み、上昇下降時間を含むプレス時間を実質的に短くすることができる。そのため、プレス位置での停留時間を短縮でき、ガラスの流出速度の増加に対応することもできる。
以上のように、得られるガラス塊において、ヒケが問題にならない場合は第２の態様が望ましく、ヒケが問題になる場合には、第１の態様を採用すればよい。
このような本発明のガラス塊の製造方法は、特に精密プレス成形用プリフォームの製造に適用することができ、具体的には、中心肉厚が薄く、直径／中心肉厚比が大きい薄肉のプリフォーム、片面のアールが大きいかまたはほぼ平面である薄肉のプリフォーム、両面アールが大きいかほぼ平面である薄肉のプリフォーム、片面が凹面である近似形状のプリフォームなどの製造に適用することができる。
A 2nd aspect is a method of manufacturing a glass lump without going through a preliminary press process and an additional press process, and has a press pre-process which is an optional process, a main press process which is an essential process, and a surface recovery process.
The contents of the pre-pressing process in the second aspect are the same as those in the first aspect described above. Further, the point that the pre-pressing process is an optional process is the same as in the first embodiment, and is a process that is not necessary when pressing is performed before the molten glass lump starts to swing on the lower mold.
The contents of the pressing step and the surface recovery step are the same as those in the first aspect described above.
The first aspect can be adopted when a depression due to sinking occurs in the center of the surface (referred to as the lower surface) facing the lower mold of the glass lump, whereas the second aspect is a single press. However, it can be employed when there is no depression due to sink marks at the bottom center of the glass block.
The preliminary pressing step in the first aspect has an effect of making the temperature distribution in the molten glass uniform, and thus is extremely effective for preventing sink marks. If the curvature radius of the bottom surface of the lower mold recess, the lower mold temperature, the outflow speed of the glass, and the lower mold are the same, it is greatly affected by the molding volume, etc., specifically, the larger the curvature radius of the bottom surface of the lower mold recess The lower the lower mold temperature, the smaller the molding volume, and the larger the outflow speed of the glass, the larger the sink at the center of the lower surface of the glass lump. Therefore, in the case where sink marks do not occur at the center of the lower surface of the glass lump, it is not always necessary to perform pre-press molding as in the second aspect.
In the second aspect, since the number of times of pressing is one, the condition parameters are reduced as compared with the case of pressing a plurality of times, and the condition setting time can be shortened. Moreover, compared with the 1st aspect, the raising / lowering of a lower mold | type (or upper mold | type) is only one time, and press time including an raising / lowering time can be shortened substantially. Therefore, the stop time at the press position can be shortened, and an increase in the outflow speed of the glass can be dealt with.
As described above, in the obtained glass lump, the second aspect is desirable when sink marks are not a problem, and the first aspect may be employed when sink marks are a problem.
Such a method for producing a glass lump of the present invention can be applied particularly to the production of a precision press-molding preform. Specifically, the glass lump has a small center wall thickness and a large diameter / center wall thickness ratio. Applicable to the manufacture of preforms, thin preforms with large or almost flat R on one side, thin preforms with large or almost flat R on both sides, approximate preforms with concave on one side Can do.
次に、本発明のガラス塊の製造装置について説明する。
本発明のガラス塊の製造装置は、複数の下型を流出ノズルに順番に供給し、連続的にキャスト、上型によるプレス成形、下型上での成形品の冷却、下型からの取り出しを繰り返すガラス塊の製造装置において、上下型の内、少なくともどちらか一方を相対的に移動させ、上下型間の間隔を接近、離間させる駆動方式にＮＣ制御方式を用い、かつ下型毎にプレス成形時のプレス厚みが補正可能であることを特徴とする。
Next, the glass lump manufacturing apparatus of the present invention will be described.
The glass lump manufacturing apparatus of the present invention sequentially supplies a plurality of lower molds to the outflow nozzle, continuously casts, press-molds with the upper mold, cools the molded product on the lower mold, and takes out from the lower mold. In a repetitive glass lump manufacturing device, the NC control method is used as the driving method to move at least one of the upper and lower molds relatively, and the distance between the upper and lower molds is approached and separated, and press molding is performed for each lower mold. The press thickness at the time can be corrected.
本発明の製造装置においては、上下型の内、少なくとも一方の上下駆動はＮＣ制御とし、各工程で行うプレス時やプレス後の離間時の型位置を個々に設定可能とする。また複数個の型を循環使用し連続的に成形する場合は、個々の型でプレス厚みを微調整可能とする。
ＮＣ制御方式による駆動方式としては、ボールネジとサーボモータを組合せ、これを駆動させるものを挙げることができる。
In the manufacturing apparatus of the present invention, at least one of the upper and lower molds is driven by NC control, and the mold position at the time of pressing performed in each process and at the time of separation after pressing can be individually set. In addition, when continuously molding a plurality of dies, the press thickness can be finely adjusted for each die.
As a driving method based on the NC control method, a combination of a ball screw and a servo motor and driving it can be cited.
本発明のガラス塊の製造装置は、本発明のガラス塊の製造方法に好適に用いることができる。本発明のガラス塊の製造方法におけるプレス前工程から追加プレス工程までのプレス工程では、上下型の間隔を間欠的に変化させる。例えばプレス前工程では、下型内の溶融ガラス塊の揺動を抑制するため、溶融ガラス上面の高さに合わせて間隔を最適化する。また予備プレス工程では、溶融ガラス内の温度分布を均一化するために、どの程度溶融ガラスを扁平化するかが非常に重要なポイントとなる。また本プレス工程でも、プレス後の表面回復や表面回復後の厚みを考慮し、プレス厚みを最適化する必要がある。更に追加プレス工程でも、プレス厚みを最適化する必要がある。また予備プレス工程では、溶融ガラスの粘性が非常に低いため、プレス速度が早すぎると、溶融ガラスが型に融着したり、下型の浮上ガスがガラス内に侵入しガラスが発泡したりする。したがって、各プレス工程に応じてプレス速度や型の離間速度を調整することが望ましい。 The glass lump production apparatus of the present invention can be suitably used for the glass lump production method of the present invention. In the press process from the pre-press process to the additional press process in the glass lump manufacturing method of the present invention, the interval between the upper and lower molds is intermittently changed. For example, in the pre-pressing process, the interval is optimized according to the height of the upper surface of the molten glass in order to suppress the fluctuation of the molten glass lump in the lower mold. In the preliminary pressing step, in order to make the temperature distribution in the molten glass uniform, how much the molten glass is flattened is a very important point. Also in this pressing step, it is necessary to optimize the press thickness in consideration of the surface recovery after pressing and the thickness after surface recovery. Furthermore, it is necessary to optimize the press thickness even in the additional pressing step. Also, in the preliminary pressing process, the viscosity of the molten glass is very low, so if the press speed is too fast, the molten glass will be fused to the mold, or the floating gas of the lower mold will enter the glass and the glass will foam. . Therefore, it is desirable to adjust the pressing speed and the mold separation speed according to each pressing step.
また、複数の下型を循環使用し、次々にキャスト、プレス成形、成形品の取り出しを行う成形法においては、下型毎に成形品の厚みやプレス面精度等に大きなバラツキが生じやすい。本発明者らが調査検討した結果、各プレス工程でのプレス厚みの小さなバラツキが、成形品寸法の大きなバラツキの原因になることが分かった。 Further, in a molding method in which a plurality of lower molds are circulated and cast, press-molded, and a molded product is taken out one after another, large variations in the thickness of the molded product, press surface accuracy, etc. tend to occur for each lower mold. As a result of investigations by the present inventors, it has been found that small variations in the press thickness in each pressing step cause large variations in the dimensions of the molded product.
型によるプレス厚みのバラツキは、下型個々の成形面の深さ精度や成形テーブル等へ下型の装着精度（着脱するため）、成型テーブルの水平度、プレス軸自体の寸法精度等によって総合的にバラツキが生じ、プレス厚みで１００μｍ以上の誤差が生じる可能性がある。 The variation in press thickness due to the mold is comprehensive depending on the depth accuracy of the molding surface of each lower mold, the mounting accuracy of the lower mold to the molding table, etc., the level of the molding table, the dimensional accuracy of the press shaft itself, etc. There is a possibility that an error of 100 μm or more may occur in the press thickness.
例えば予備プレスでは、溶融ガラスをプレスし溶融ガラスの中央と外周、上下面と内部で熱交換させ温度分布を均一化する。したがってプレス厚みの差が１００μｍ程度であっ
ても、溶融ガラスと上下型の熱交換、そして外周と内部での熱交換に大きな差が生じ、面回復工程を経た成形品の寸法バラツキは２〜５倍にも拡大する。つまりプレス厚みによって、面回復工程での寸法変化量が大きく変わるからである。同様に、溶融ガラス内の温度分布の均一化の程度もプレス厚みによって大きく影響を受ける。そのため、冷却中にヒケないものと、ヒケ気味なものが混在してしまうことになる。そこで本発明では、上下型の少なくとも一方の駆動にＮＣ制御方式を採用し、下型毎にプレス厚みを補正する方法を用いる。この方法により、成形装置や下型や上型といった成形型の寸法誤差の影響をキャンセルすることが可能となる。一方、下型温度や下型からの噴出ガス量などのバラツキも、成形品の寸法バラツキ原因となる。しかし、プレス厚みの個別調整を行うことで、これらのバラツキ要因は充分に補正可能となる。このような場合、下型温度や噴出ガス量などのバラツキの影響を補正するため、各型でのプレス厚みは全く同じに揃える必要はない。つまり、成形品の寸法が揃うようにプレス厚みを個別に微調整すれば良い。
For example, in the preliminary press, the molten glass is pressed and heat exchange is performed between the center and outer periphery, the upper and lower surfaces, and the inside of the molten glass to make the temperature distribution uniform. Therefore, even if the difference in press thickness is about 100 μm, a large difference occurs in the heat exchange between the molten glass and the upper and lower molds, and the heat exchange between the outer periphery and the inside, and the dimensional variation of the molded product after the surface recovery process is 2 to 5 It will be doubled. That is, the amount of dimensional change in the surface recovery process varies greatly depending on the press thickness. Similarly, the degree of temperature distribution in the molten glass is greatly affected by the press thickness. Therefore, there will be a mixture of a non-sinking thing and a sinking thing during cooling. Therefore, in the present invention, an NC control method is adopted for driving at least one of the upper and lower molds, and a method of correcting the press thickness for each lower mold is used. By this method, it becomes possible to cancel the influence of the dimensional error of the molding die such as the molding device, the lower die and the upper die. On the other hand, variations in the lower mold temperature and the amount of gas ejected from the lower mold also cause dimensional variations in the molded product. However, by performing individual adjustment of the press thickness, these variation factors can be sufficiently corrected. In such a case, the press thicknesses in the respective molds do not have to be exactly the same in order to correct the influence of variations such as the lower mold temperature and the amount of ejected gas. That is, the press thickness may be finely adjusted individually so that the dimensions of the molded product are uniform.
前記補正は例えば以下のように行う。
前記したプレス法により各下型で３回ずつ成形したプリフォームの中心厚みを測定する。次に全プリフォームの中心厚みの平均値を求め、各下型で成形したプリフォームの厚みの平均値との差を求める。この寸法差と同じ分だけ下型毎にプレス厚みを補正する。例えば中心厚みの平均より２００μｍだけ厚い場合は、プレス厚みを２００μｍ薄くする。この補正操作を全ての下型で行い、再び中心厚みを測定する。測定の結果に応じて補正値を再設定し、最終的に各下型で成形したプリフォームの厚みバラツキが所望の精度に入るまで調整する。このようにして、下型毎の寸法バラツキを均一化した後、中心厚みの絶対値が規格内に入るようにプレス厚みを一括調整する。このように、プレス厚みは全下型で一括調整する方法と個別に微調整する方法を備えることが望ましい。
For example, the correction is performed as follows.
The center thickness of the preform molded three times with each lower mold by the press method described above is measured. Next, the average value of the center thicknesses of all the preforms is obtained, and the difference from the average value of the thicknesses of the preforms molded with the respective lower molds is obtained. The press thickness is corrected for each lower die by the same amount as this dimensional difference. For example, when the thickness is 200 μm thicker than the average of the center thickness, the press thickness is reduced by 200 μm. This correction operation is performed on all lower molds, and the center thickness is measured again. The correction value is reset according to the measurement result, and finally adjusted until the thickness variation of the preform formed by each lower mold falls within a desired accuracy. In this way, after uniforming the dimensional variation for each lower mold, the press thickness is collectively adjusted so that the absolute value of the center thickness falls within the standard. As described above, it is desirable to provide a method for collectively adjusting the press thickness with the lower die and a method for finely adjusting the thickness individually.
このような本発明のガラス塊の製造装置は、特に精密プレス成形用プリフォームの製造に好適に用いられる。 Such a glass lump production apparatus of the present invention is particularly suitable for production of a precision press-molding preform.
次に、本発明の光学素子の製造方法について説明する。
本発明の光学素子の製造方法は、前述の本発明のガラス塊の製造方法で作製された精密プレス成形用プリフォームを精密プレス成形することを特徴とする。
Next, the manufacturing method of the optical element of this invention is demonstrated.
The method for producing an optical element of the present invention is characterized by precision press-molding a precision press-molding preform produced by the above-described glass lump production method of the present invention.
精密プレス成形とは、プリフォームを加熱、軟化した状態で所定形状のキャビティを有する成形型によって加圧成形し、最終製品の形状と同じまたは極めて近似した形状の成形品を作製する方法である。精密プレス成形法によれば、成形品に研削や研磨を施さずに、あるいは研磨による除去量が極めて少ない研磨のみを施すことによって、最終製品、特に光学部品のような極めて高い形状精度や面精度を要求される最終製品を作製することが可能である。そのため、本発明の光学素子の製造方法は、レンズ、レンズアレイ、回折格子、プリズムなどの光学部品の製造に好適であり、特に非球面レンズを高生産性のもとに製造する際に最適である。 Precision press molding is a method of producing a molded product having a shape that is the same as or very close to the shape of the final product by pressure molding with a mold having a cavity of a predetermined shape while the preform is heated and softened. According to the precision press molding method, extremely high shape accuracy and surface accuracy such as final products, especially optical parts, can be obtained without grinding or polishing the molded product, or by applying only polishing with very little removal by polishing. It is possible to produce a final product that is required. Therefore, the optical element manufacturing method of the present invention is suitable for manufacturing optical components such as lenses, lens arrays, diffraction gratings, and prisms, and is particularly suitable for manufacturing aspherical lenses with high productivity. is there.
精密プレス成形方法としては、表面が清浄状態のプリフォームを、プリフォームを構成するガラスの粘度が１０５〜１０１１Ｐａ・ｓの範囲を示すように再加熱し、再加熱されたプリフォームを上型、下型を備えた成形型によってプレス成形する。成形型の成形面には必要に応じて離型膜を設けてもよい。なお、プレス成形は、成形型の成形面の酸化を防止する上から、窒素ガスや不活性ガス雰囲気で行うことが好ましい。プレス成形品は成形型より取り出され、必要に応じて徐冷される。成形品がレンズなどの光学素子の場合には、必要に応じて表面に光学薄膜をコートしてもよい。 As a precision press molding method, a preform with a clean surface is reheated so that the viscosity of the glass constituting the preform is in the range of 10 5 to 10 11 Pa · s, and the reheated preform is Press molding is performed with a mold having an upper mold and a lower mold. A mold release film may be provided on the molding surface of the mold as necessary. The press molding is preferably performed in an atmosphere of nitrogen gas or inert gas in order to prevent oxidation of the molding surface of the mold. The press-molded product is taken out from the mold and gradually cooled as necessary. When the molded product is an optical element such as a lens, an optical thin film may be coated on the surface as necessary.
以下、本発明を実施例によりさらに具体的に説明するが、本発明はこれらの実施例によ
ってなんら限定されるものではない。
なお、図１は、実施例および比較例で用いた円形の成形テーブルにおける下型の配置図である。 図２は、実施例におけるキャスト後のプレス工程の説明図である。
また、以下の実施例においては、上型または下型を相対的に移動させることにより上下型間の間隔を接近させまたは離間させる駆動方式として、いずれもＮＣ制御方式を用い、ボールネジとサーボモータを組合せ、これを駆動させることにより行った。
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
FIG. 1 is a layout diagram of lower molds in a circular molding table used in Examples and Comparative Examples. FIG. 2 is an explanatory diagram of a pressing process after casting in the example.
In the following embodiments, the NC control method is used as the drive method for moving the upper die or the lower die relative to each other so that the distance between the upper and lower die approaches or separates. This was done by driving the combination.
実施例１（第１の態様によるプリフォームの製造例（基本的な方法））
溶融・冷却・固化後に屈折率［ｎｄ］：１．８０６、アッベ数［νｄ］：４０．７のホウ酸ランタン系の光学ガラスとなるガラス塊を１０００℃に加熱した白金ルツボに投入してルツボ内で溶解後、１３００℃で清澄、撹拌し均一なガラス融液を得た。次に、ルツボ底部に連結し温度制御した流出パイプから０．７９ｋｇ／ｈｒの流出速度でガラス融液を流出させた。一方、図１のように、円形の成形テーブルの外周上に１２個の下型を均等に配置した。下型の上部には、溶融ガラスをキャストする凹部（直径：φ１７ｍｍ、底面アール：３０ｍｍ）が加工されている。凹部は平均穴径が２０μｍの多孔質材料からなり、多孔質材料表面からは０．２Ｌ／分の窒素が均一に噴き出している。なお型本体部はヒーターで加熱し、凹部の表面温度を３２０℃とした。
Example 1 (Preparation example of the preform according to the first aspect (basic method))
A glass lump that becomes a lanthanum borate optical glass having a refractive index [nd]: 1.806 and an Abbe number [νd]: 40.7 after melting, cooling, and solidification is charged into a platinum crucible heated to 1000 ° C. After melting in the inside, it was clarified and stirred at 1300 ° C. to obtain a uniform glass melt. Next, the glass melt was discharged from the outlet pipe connected to the bottom of the crucible and controlled in temperature at an outlet speed of 0.79 kg / hr. On the other hand, as shown in FIG. 1, twelve lower molds were evenly arranged on the outer periphery of a circular molding table. A concave portion (diameter: φ17 mm, bottom radius: 30 mm) for casting molten glass is processed in the upper part of the lower mold. The recess is made of a porous material having an average hole diameter of 20 μm, and 0.2 L / min of nitrogen is uniformly ejected from the surface of the porous material. The mold body was heated with a heater, and the surface temperature of the recesses was set to 320 ° C.
次に、流出口の直下に下型を供給し、以下のように溶融ガラスを下型にキャストした。まず下型を上昇させ流出口に接近させた状態とし、溶融ガラス流の先端を下型の凹部で受ける。下型の凹部に所望重量の溶融ガラスが溜まった時に下型を急降下し、溶融ガラス流から下型上に溶融ガラス塊を切断分離した。 Next, the lower mold | type was supplied directly under the outflow port, and the molten glass was cast to the lower mold | type as follows. First, the lower mold is raised and brought close to the outlet, and the tip of the molten glass flow is received by the recess of the lower mold. When a desired weight of molten glass accumulated in the recess of the lower mold, the lower mold was rapidly lowered, and the molten glass lump was cut and separated from the molten glass flow onto the lower mold.
次に、成形テーブルをインデックス回転させ、流出口の直下から成形型を退避させると同時に、別の下型をノズル直下に供給した。順次同様な操作を７．１７秒間隔で繰り返し、次々に溶融ガラス流を分離・切断し下型上に４６９ｍｍ３の溶融ガラス塊を得た。次に、キャスト後のプレス工程について図２を用いて説明する。 Next, the forming table was rotated by an index, and the forming die was retracted from directly under the outlet, and another lower die was supplied immediately below the nozzle. The same operation was sequentially repeated at intervals of 7.17 seconds, and the molten glass flow was successively separated and cut to obtain a molten glass lump of 469 mm 3 on the lower mold. Next, the pressing process after casting will be described with reference to FIG.
キャストし流出口から退避した直後の溶融ガラス塊は、移動による慣性力で揺れている。この揺れが停止するタイミング（下型の停止から０．５秒後）をはかり、以下のような上型を溶融ガラス塊上に降下させ保持した。上型は直径がφ１５ｍｍの耐熱ステンレスからなり、下面にはアール３０ｍｍの凹状の球面研磨加工が施されている。また上型内部には空洞を形成してあり、空洞内に２０Ｌ／分の窒素ガスを流して上型を冷却した。上型の保持位置は、溶融ガラス塊と上型が触れるか触れないかぎりぎりの位置とし、ガスクッションによる溶融ガラス塊の揺動を規制した。次に下型の停止から０．８秒後に、上下型中心部の距離（プレス厚み）が３．９ｍｍになるまで下型を上昇させ１．７秒間保持後に下型を降下させプレス状態を解除した。プレスの解除後の溶融ガラス塊は、表面張力で厚みがプレス前の８割程度まで回復した。なお下型の保持位置は、厚みが回復後の溶融ガラスの揺動を上型で規制できる位置に保持することが望ましい。 The molten glass lump immediately after casting and retreating from the outlet is swayed by the inertial force due to movement. The timing at which this shaking stops (0.5 seconds after the lower mold stopped) was measured, and the upper mold as shown below was lowered onto the molten glass lump and held. The upper mold is made of heat-resistant stainless steel having a diameter of φ15 mm, and a concave spherical polishing process with a radius of 30 mm is applied to the lower surface. A cavity was formed inside the upper mold, and the upper mold was cooled by flowing nitrogen gas of 20 L / min into the cavity. The holding position of the upper mold was a limit position as long as the molten glass lump and the upper mold were not touched or touched, and the rocking of the molten glass lump by the gas cushion was regulated. Next, 0.8 seconds after the lower mold stops, the lower mold is raised until the distance between the upper and lower mold centers (press thickness) reaches 3.9 mm. After holding for 1.7 seconds, the lower mold is lowered to release the press state. did. The molten glass lump after the press release was recovered to about 80% of the thickness before the press due to the surface tension. The holding position of the lower mold is desirably held at a position where the upper mold can regulate the oscillation of the molten glass after the thickness is restored.
プレス解除から０．５秒経過後に下型を再上昇させ、プレス厚みが４．１ｍｍとなるよう溶融ガラスを１．５秒間プレス成形した後で下型を下限位置まで急降下させた。この２回の間欠プレスから２．６７秒後に成形テーブルをインデックス回転させ、下型を第３停留位置に移動させた。 After 0.5 seconds had elapsed from the release of the press, the lower mold was raised again, the molten glass was press-molded for 1.5 seconds so that the press thickness was 4.1 mm, and then the lower mold was rapidly lowered to the lower limit position. After 2.67 seconds from the two intermittent presses, the molding table was indexed to move the lower mold to the third stop position.
２回目のプレス成形直後は、プレス面に冷却収縮による軽微な凸凹が生じた。この表面の凸凹は、下型が第３停留位置に停止してから１．４秒後にほぼ自然消失し、プレス面は自由表面と遜色がない滑らかな面に回復した。上記のプレス工程により得られたプリフォームは、平均直径がφ１４．３ｍｍで中心厚みが４．２ｍｍの扁平な碁石に似た形状となり上下面とも精密プレス用プリフォームとして全く問題ない品質の面であった。表１は、
各プリフォームの中心厚みの測定結果である。但し、１２個の下型で連続的にプレス成形しているため、表１のように下型毎に中心厚みが２００〜２８０μｍばらついていた。その一方で、同じ下型で成形したプリフォーム間のバラツキは、１０〜１１０μｍと小さかった。
Immediately after the second press molding, slight unevenness due to cooling shrinkage occurred on the press surface. The unevenness of the surface almost disappeared spontaneously 1.4 seconds after the lower die stopped at the third stop position, and the pressed surface recovered to a smooth surface that was not inferior to the free surface. The preform obtained by the above pressing process has a shape resembling a flat meteorite with an average diameter of φ14.3 mm and a center thickness of 4.2 mm. there were. Table 1 shows
It is a measurement result of the center thickness of each preform. However, since the 12 lower molds were continuously press-molded, the center thickness varied from 200 to 280 μm for each lower mold as shown in Table 1. On the other hand, the variation between the preforms molded with the same lower mold was as small as 10 to 110 μm.
実施例２（第１の態様によるプリフォームの製造例（中心厚みの均一化例））
２回目のプレス時間を１．５秒から１．３秒に変更した以外は、実施例１と全く同じ方法と条件でプリフォームを成形した。表２は本条件で成形した各プリフォームの中心厚みの測定結果である。表２のように、２回目のプレス時間短縮によりプレス後の厚みの変化が増大し、実施例１（表１）より平均厚みが１３３μｍ厚くなった。また下型毎のバラツキも３２０〜４１０μｍに増大している。一方で、同じ下型で成形したプリフォーム間のバラツキは、１０〜９０μｍと小さかった。
Example 2 (Preform production example according to the first aspect (example of uniform center thickness))
A preform was molded by the same method and conditions as in Example 1 except that the second press time was changed from 1.5 seconds to 1.3 seconds. Table 2 shows the measurement results of the center thickness of each preform molded under these conditions. As shown in Table 2, the change in thickness after pressing was increased by shortening the second pressing time, and the average thickness was 133 μm thicker than Example 1 (Table 1). Moreover, the dispersion | variation for every lower mold | type has also increased to 320-410 micrometers. On the other hand, the variation between the preforms molded with the same lower mold was as small as 10 to 90 μm.
実施例２では２回目のプレス時間が短いため、プレス後の形状変化が大きめとなる。そのためプレス型（上型）よりプリフォームプレス面のアールがやや小さくなる。特に外周部のアール形状は非球面となり、アールが小さくなる傾向が強い。そこでこの形状差を小さくするため、第３停留位置で追加プレスを行った。なお追加プレスを行う以外は実施例２と同条件とした。なお追加プレス用の上型は、２回目のプレスまで使用した上型と同規格であるが、プレス面に硬質クロムメッキが施されている。このメッキは型を加熱するため、酸化防止やガラスの融着防止のために行う。同じ効果を得る膜としては、ニッケルメッキや、ＣｒＮ、ＴｉＮ、ＴｉＡｌＮ等の窒化物単層膜又は、２種類以上の窒化物を組み合わせた複層膜、そして高温耐性が強いＤＬＣ膜等が使用できる。追加プレス用のプレス型はヒーターで２５０℃以上に加熱し、前記した収縮による凸凹が生じないようにする。なお本実施例では、追加プレスの上型を３２０℃に加熱した。追加プレスのタイミングは、２回目のプレスで生じたプレス面の凸凹が自然回復後に行う。
In Example 2, since the second pressing time is short, the shape change after pressing becomes larger. Therefore, the radius of the preform press surface is slightly smaller than that of the press die (upper die). In particular, the round shape of the outer peripheral portion becomes an aspherical surface, and there is a strong tendency that the round shape becomes small. Therefore, in order to reduce this shape difference, additional pressing was performed at the third stop position. The conditions were the same as in Example 2 except that additional pressing was performed. The upper die for the additional press has the same standard as the upper die used up to the second press, but the press surface is hard chrome plated. This plating is performed to prevent oxidation and glass fusion in order to heat the mold. As a film having the same effect, nickel plating, a nitride single layer film such as CrN, TiN, TiAlN or the like, a multilayer film combining two or more types of nitrides, and a DLC film having a high temperature resistance can be used. . The press die for the additional press is heated to 250 ° C. or higher with a heater so that the unevenness due to the shrinkage described above does not occur. In this example, the upper die of the additional press was heated to 320 ° C. The timing of the additional press is performed after the unevenness of the press surface generated in the second press naturally recovers.
本実施例では、下型が第３の停留位置に停止してから０．８秒後に上型を溶融ガラス塊の真上に停止させ、まず上型と溶融ガラス塊の中心位置を合わせた。その０．９秒後に下型を上昇させ、上下型の中心間距離が４．０ｍｍとなるよう０．９秒間プレス成形した。プレス成形後は下型を下限位置に、上型を退避位置にそれぞれ戻した。追加プレスは加熱した型でプレスするため、プレス直後もプレス面に凸凹が生じない。本方法で連続的にプリフォームを成形し得られたプリフォームの形状を測定した。プレス面のアールは、型のアール（３０ｍｍ）と同じであり、下面のアールもほぼ３０ｍｍアールとなっていた。以上のように追加プレスを行うことで、プレス面のアールを型のアールに近づけることができた。 In this example, 0.8 seconds after the lower mold stopped at the third stop position, the upper mold was stopped just above the molten glass lump, and first, the center positions of the upper mold and molten glass lump were aligned. 0.9 seconds later, the lower mold was raised, and press molding was performed for 0.9 seconds so that the distance between the centers of the upper and lower molds was 4.0 mm. After press molding, the lower mold was returned to the lower limit position, and the upper mold was returned to the retracted position. Since the additional press is pressed with a heated die, unevenness does not occur on the press surface immediately after pressing. The shape of the preform obtained by continuously molding the preform by this method was measured. The radius of the press surface is the same as the radius of the mold (30 mm), and the radius of the lower surface is also approximately 30 mm. By performing additional pressing as described above, the radius of the press surface could be brought close to the radius of the mold.
実施例４（第１の態様によるプリフォームの製造例（加熱による表面回復例））
実施例１で説明した２回目のプレス時間を２．８秒間とした以外は実施例１と全く同一条件で成形した。その結果、プレス面にはプレスによる冷却により凸凹が生じ、プレス面の自然回復は起こらなかった。そこで本実施例では、第３の停留位置でプレス面を外部から加熱した。なお加熱は、７５０℃に加熱した窒素ガスを５秒間（１０Ｌ／分）吹き付けることで行った。 ガスヒーターとしては、コイル状に巻き断熱材で保温した白金管を通電加熱し、その中に窒素ガスを通すことで行った。他の方法としては、通電加熱のかわりに白金管を高周波加熱する方法も使用できる。一方、輻射熱でプレス面を加熱する場合は、加熱物をプレス面の上部に保持する方法が使用できる。加熱物としては、白金板自身を通電や高周波により加熱する方法や、カンタル線などの一般的なヒーターで加熱した板を使用しても良い。その他、赤外線ヒーター等もプレス面の加熱に使用できる。
Example 4 (Preform production example according to the first aspect (example of surface recovery by heating))
Molding was performed under exactly the same conditions as in Example 1 except that the second pressing time described in Example 1 was 2.8 seconds. As a result, the press surface was uneven due to cooling by the press, and natural recovery of the press surface did not occur. Therefore, in this example, the press surface was heated from the outside at the third stop position. The heating was performed by blowing nitrogen gas heated to 750 ° C. for 5 seconds (10 L / min). As the gas heater, a platinum tube which was wound in a coil shape and kept warm with a heat insulating material was energized and heated, and nitrogen gas was passed through it. As another method, a method in which a platinum tube is heated at a high frequency instead of energization heating can be used. On the other hand, when heating a press surface with radiant heat, the method of hold | maintaining a heating thing on the upper part of a press surface can be used. As the heated object, a method of heating the platinum plate itself by energization or high frequency, or a plate heated by a general heater such as Kanthal wire may be used. In addition, an infrared heater or the like can be used for heating the press surface.
上記加熱によりプレス面の凸凹は自由表面に回復した。自由表面化は外部から熱で行うため、与える熱を最小化することで寸法変化を最小限に小さくすることが可能となる。よ
って、実施例１の方法で得られるプリフォームよりも、プレス面の形状精度が得られやすい。
The unevenness of the press surface was restored to the free surface by the heating. Since the free surface formation is performed by heat from the outside, it is possible to minimize the dimensional change by minimizing the applied heat. Therefore, it is easier to obtain the shape accuracy of the press surface than the preform obtained by the method of Example 1.
実施例５（第２の態様によるプリフォームの製造例）
成形型（上下型）とプレス成形条件を変更した以外は実施例１と全く同じ装置とガラスを用い、以下のようにプリフォームを成形した。
まず下型の凹部寸法は開口部直径がφ１７mmで底面曲率半径が２０mmのものに変更した。但し、凹部は実施例１と同じ多孔質材料からなり、凹部表面から０．２５L／分の窒素ガスを噴きださせ、型本体部はヒーターで３７０℃に加熱した。一方、上型は直径φ１３mmの耐熱ステンレスからなり、下面に凹状でアール６０mmの球面研磨加工を施した。また上型の内部は中空構造とし、空洞内に１５Ｌ／分の窒素ガスを流し空冷した。なおガラス融液の流出速度やガラス流の切断・分離方法は実施例１と同じである。
下型の凹部に４６９mm3の溶融ガラスをキャスト後、下型を第２の停留位置に停止させた直後に上型を高速で降下させ、溶融ガラス塊の上端から０．２mm上方に上型の下面を停止させた。次に下型内での溶融ガラスの揺動が停止するタイミング（下型停止から０．８秒）で上下型の中心部の距離（プレス厚み）が３．９０ｍｍになるまで下型を低速で上昇させ、溶融ガラス塊を３．６秒間プレス成形した。プレス後は上下型をプレス前の位置に戻し、プレス解除から２．７７秒後に成形テーブルをインデックス回転させ、下型を第３の停留位置に移動させた。このプレス操作により溶融ガラス塊は扁平化し、プレス直後のプレス面には冷却収縮による軽微な凸凹が生じた。しかし表面の凸凹は、下型が第３停留位置に停止してから１．６秒後にほぼ自然消失し、プレス面は自由表面と遜色が無い滑らかな面に回復した。その後の第４〜第９停留位置ではプリフォーム上面に７〜１０Ｌ／分の窒素ガスを吹きかけて風冷し、第１０停留位置で成形品を取り出した。
上記のプレス工程により得られたプリフォームは、平均直径がφ１３．９mmで中心厚みが４．１２mmの扁平な碁石に似た形状となった。またプレス面の平均曲率半径は４０mmと平面に近く、下型に面していた面の平均曲率半径は２７mmであり、ヒケによる窪みは見られなかった。
１回のプレスでも得られたプリフォームにヒケが生じなかった主な理由は、下型の底面曲率半径であると考えられることから、開口部直径がφ１７ｍｍで、底面アールが１７ｍｍ、２３ｍｍ、２７ｍｍと３種類の下型を用意し、それぞれ３．６秒間の１回プレスでプリフォームを成形した。その結果、底面曲率半径が１７ｍｍと２３ｍｍの下型で成形したプリフォームは、それぞれ下面曲率半径が２２ｍｍと３０ｍｍとなり、ヒケによる窪みは見られなかった。しかしながら、底面曲率半径が２７ｍｍの下型で成形したプリフォームは下面がヒケ気味となり平面状となった。
Example 5 (Preparation example of preform according to the second aspect)
A preform was molded as follows using the same apparatus and glass as in Example 1 except that the molding die (upper and lower molds) and press molding conditions were changed.
First, the recess size of the lower mold was changed to one having an opening diameter of φ17 mm and a bottom surface curvature radius of 20 mm. However, the recess was made of the same porous material as in Example 1, 0.25 L / min of nitrogen gas was spouted from the surface of the recess, and the mold body was heated to 370 ° C. with a heater. On the other hand, the upper mold was made of heat-resistant stainless steel with a diameter of 13 mm, and the bottom surface was concave and was subjected to spherical polishing with a radius of 60 mm. Further, the inside of the upper mold was made into a hollow structure, and air was cooled by flowing nitrogen gas of 15 L / min into the cavity. The outflow speed of the glass melt and the method of cutting / separating the glass flow are the same as in the first embodiment.
After casting 469 mm 3 of molten glass into the lower mold recess, immediately after the lower mold is stopped at the second stop position, the upper mold is lowered at high speed, and the upper mold is 0.2 mm above the upper end of the molten glass lump. The lower surface was stopped. Next, the lower mold is moved at a low speed until the distance (press thickness) between the upper and lower molds reaches 3.90 mm at the timing when the oscillation of the molten glass in the lower mold stops (0.8 seconds after the lower mold stops). The molten glass mass was press molded for 3.6 seconds. After pressing, the upper and lower molds were returned to the position before pressing, and after 2.77 seconds from the release of the press, the forming table was rotated by an index, and the lower mold was moved to the third stop position. By this pressing operation, the molten glass lump was flattened, and slight unevenness due to cooling shrinkage occurred on the pressing surface immediately after pressing. However, the irregularities on the surface almost disappeared spontaneously 1.6 seconds after the lower die stopped at the third stop position, and the pressed surface recovered to a smooth surface that was comparable to the free surface. Subsequently, 7 to 10 L / min of nitrogen gas was blown onto the upper surface of the preform at the 4th to 9th stop positions, and the product was taken out at the 10th stop position.
The preform obtained by the above pressing process had a shape similar to a flat meteorite having an average diameter of φ13.9 mm and a center thickness of 4.12 mm. Further, the average curvature radius of the press surface was 40 mm, which was close to a flat surface, and the average curvature radius of the surface facing the lower mold was 27 mm, and no depression due to sink marks was observed.
The main reason why sinking did not occur in the preform obtained even in a single press was considered to be the bottom surface radius of curvature of the lower mold, so the opening diameter was 17 mm, and the bottom surface radius was 17 mm, 23 mm, 27 mm. 3 types of lower molds were prepared, and preforms were formed by a single press for 3.6 seconds each. As a result, the preforms molded with lower molds having a bottom surface curvature radius of 17 mm and 23 mm had bottom surface curvature radii of 22 mm and 30 mm, respectively, and no depression due to sink marks was observed. However, the preform formed with a lower mold having a bottom surface curvature radius of 27 mm had a flat bottom surface and a flat surface.
実施例６（第２の態様によるプリフォームの製造例）
溶融ガラス塊の成形容量とプレス成形条件のみを変更した以外は実施例１と全く同じ成形型（上下型）と成形装置、そしてガラスを用い、同じ流出速度（０．７９ｋｇ／ｈｒ）で以下のようにプリフォームを成形した。
まず、実施例１よりプリフォーム容量を大きくするため、キャストの開始から下型急降下によるガラス流切断までの時間を９．６３秒（実施例１は７．１７秒）に延長し、下型上に６３０ｍｍ3の溶融ガラス塊を得た。次に下型を第２の停留位置に移動させ停止させた直後に上型を高速で降下させ、溶融ガラス塊上端から０．１mm上方に上型の下面を停止させた。次に下型内での溶融ガラスの揺動が停止するタイミング（下型停止から０．８秒）で上下型の中心部の距離（プレス厚み）が４．３ｍｍなるまで下型を低速で上昇させ、溶融ガラス塊を４．９０秒間プレス成形した。プレス後は上下型をプレス前の位置に戻し、プレス解除から３．９３秒後に成形テーブルをインデックス回転させ、下型を第３の停留位置に移動させた。このプレス操作により溶融ガラス塊は扁平化し、プレス直後のプレス面には冷却収縮による軽微な凸凹が生じた。しかし表面の凸凹は、下型が第３停留位置に停止してから２．８秒後にほぼ自然に消失し、プレス面は自由表面と遜色が無い滑らか
な面に回復した。その後の第４〜第９停留位置ではプリフォーム上面に７〜１０Ｌ／分の窒素ガスを吹きかけて風冷し、第１０停留位置で成形品を取り出した。
上記のプレス工程により得られたプリフォームは、平均直径がφ１６．２mmで中心厚みが４．４７mmの扁平な碁石に似た形状となった。またプレス面の平均アールは２８mmと上型のアールに近く、下型に面していた面の平均アールは２７mmとなりヒケによる窪みは見られなかった。
１回のプレスでも得られたプリフォームにヒケが生じなかった主な理由は、成形容量であると考えられることから、成形容量を５２０ｍｍ３、５７０ｍｍ３と変更し、それぞれ３．５秒間、３．９秒間の１回プレスによりプリフォームを成形した。その結果、両プリフォームとも碁石状となり、下面側にヒケによる窪みは見られなかった。但し、成形容量が５７０ｍｍ３では下面側アールが３１ｍｍ、成形容量が５２０ｍｍ3では下面側アールが４８ｍｍと、成形容量が小さくなるに従って下面側のアールが大きくなる傾向が見られた。この下面側アールの変化は、下面側のヒケ傾向によるものと思われる。
Example 6 (Preparation Example of Preform According to Second Aspect)
Except for changing only the molding capacity and press molding conditions of the molten glass lump, the same mold (upper and lower molds) and molding apparatus as in Example 1 and glass were used, and the following outflow rate (0.79 kg / hr) was used. A preform was molded as follows.
First, in order to make the preform capacity larger than that in Example 1, the time from the start of casting to the glass flow cutting due to the rapid lowering of the lower mold was extended to 9.63 seconds (7.17 seconds in Example 1). A molten glass lump of 630 mm 3 was obtained. Next, immediately after the lower mold was moved to the second stop position and stopped, the upper mold was lowered at a high speed, and the lower surface of the upper mold was stopped 0.1 mm above the upper end of the molten glass lump. Next, at the timing when the oscillation of the molten glass in the lower mold stops (0.8 seconds after the lower mold stops), the lower mold is raised at a low speed until the distance between the upper and lower mold centers (press thickness) reaches 4.3 mm. The molten glass lump was press-molded for 4.90 seconds. After pressing, the upper and lower molds were returned to the position before pressing, and after 3.93 seconds from the release of the press, the forming table was rotated by an index, and the lower mold was moved to the third stop position. By this pressing operation, the molten glass lump was flattened, and slight unevenness due to cooling shrinkage occurred on the pressing surface immediately after pressing. However, the unevenness of the surface disappeared almost naturally 2.8 seconds after the lower mold stopped at the third stop position, and the pressed surface recovered to a smooth surface that was comparable to the free surface. Subsequently, 7 to 10 L / min of nitrogen gas was blown onto the upper surface of the preform at the 4th to 9th stop positions, and the product was taken out at the 10th stop position.
The preform obtained by the above pressing process had a shape similar to a flat meteorite with an average diameter of φ16.2 mm and a center thickness of 4.47 mm. The average radius of the press surface was 28 mm, which is close to the upper die radius, and the average radius of the surface facing the lower die was 27 mm, and no depression due to sink marks was observed.
The main reason why sinks did not occur in the preform obtained even in a single press was considered to be the molding capacity, so the molding capacity was changed to 520 mm 3 and 570 mm 3 for 3.5 seconds each. A preform was formed by a single press for 9 seconds. As a result, both preforms were in the form of meteorites, and no depression due to sink marks was observed on the lower surface side. However, when the molding capacity was 570 mm 3 , the lower surface side radius was 31 mm, and when the molding capacity was 520 mm 3 , the lower surface side radius was 48 mm. This change in the lower surface side radius is considered to be due to the sinking tendency on the lower surface side.
なお、実施例１〜６においては、図１において第４〜９停留位置で冷却工程が行われ、それぞれ第１０停留位置で成形品の取り出しが行われる。 In Examples 1 to 6, the cooling process is performed at the fourth to ninth stop positions in FIG. 1, and the molded product is taken out at the tenth stop position.
実施例７
実施例１〜６で成形されたプリフォームを再加熱、軟化して窒素雰囲気中において成形型により精密プレス成形して、非球面レンズなどの光学素子を作製した。得られた光学素子はいずれも要求される性能を満たすものであった。
各光学素子の光学機能面には、必要に応じて反射防止膜などの光学薄膜を形成した。
Example 7
The preforms molded in Examples 1 to 6 were reheated and softened and precision press-molded with a mold in a nitrogen atmosphere to produce an optical element such as an aspheric lens. All of the obtained optical elements satisfied the required performance.
An optical thin film such as an antireflection film was formed on the optical functional surface of each optical element as necessary.
本発明のガラス塊の製造方法は、精密プレス成形用プリフォーム、例えば中心肉厚が薄く、直径／中心肉厚比が大きい薄肉のプリフォーム、片面のアールが大きいかまたはほぼ平面である薄肉のプリフォーム、両面アールが大きいかほぼ平面である薄肉のプリフォーム、片面が凹面である近似形状のプリフォームなどを、寸法精度よく、高い生産性のもとで製造することができる。 The method for producing a glass lump according to the present invention is a precision press-molding preform, for example, a thin preform having a thin center thickness and a large diameter / center thickness ratio, a thin wall having a large radius on one side or substantially flat. Preforms, thin-walled preforms having large or substantially double-sided rounds, approximate preforms having a concave surface on one side, and the like can be manufactured with high dimensional accuracy and high productivity.
Claims (10)
下型上の溶融ガラス塊を上型に直接接触させた状態でプレスし、溶融ガラス塊の形状を固定後、プレス面に生じた表面のうねりを回復させ、自由表面化することを特徴とするガラス塊の製造方法。 In the process of receiving the molten glass flow flowing out from the outflow pipe with the lower mold, cutting the glass flow to obtain the molten glass lump on the lower mold, and forming the glass lump by cooling while substantially floating on the lower mold,
A glass characterized by pressing the molten glass lump on the lower mold in direct contact with the upper mold, fixing the shape of the molten glass lump, then recovering the swell of the surface generated on the pressing surface, and making it a free surface A method of manufacturing a lump.
上下型の内、少なくともどちらか一方を相対的に移動させ、上下型間の間隔を接近、離間させる駆動方式にＮＣ制御方式を用い、かつ下型毎にプレス成形時のプレス厚みを補正する請求項１〜７のいずれか１項に記載のガラス塊の製造方法。 In order to produce a glass lump by supplying a plurality of lower dies in order to the outflow nozzle, continuously casting, press molding with the upper die, cooling the molded product on the lower die, and taking out from the lower die.
An NC control method is used as a driving method for moving at least one of the upper and lower molds relatively so that the interval between the upper and lower molds approaches and separates, and the press thickness during press molding is corrected for each lower mold. The manufacturing method of the glass lump of any one of claim | item 1 -7 .
The method of manufacturing an optical device characterized by claim 7 or manufactured Riga Las mass by the method described in 9, precision press molding the resulting glass block.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2006213113A JP4368368B2 (en) | 2005-09-27 | 2006-08-04 | Manufacturing method of glass lump, manufacturing apparatus thereof, and manufacturing method of optical element |
| CN2006101399495A CN1939850B (en) | 2005-09-27 | 2006-09-27 | Manufacturing method of glass block, manufacturing device thereof and manufacturing method of optical element |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005279187 | 2005-09-27 | ||
| JP2006213113A JP4368368B2 (en) | 2005-09-27 | 2006-08-04 | Manufacturing method of glass lump, manufacturing apparatus thereof, and manufacturing method of optical element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2007119335A JP2007119335A (en) | 2007-05-17 |
| JP4368368B2 true JP4368368B2 (en) | 2009-11-18 |
Family
ID=38143563
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2006213113A Expired - Fee Related JP4368368B2 (en) | 2005-09-27 | 2006-08-04 | Manufacturing method of glass lump, manufacturing apparatus thereof, and manufacturing method of optical element |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP4368368B2 (en) |
| CN (1) | CN1939850B (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5138401B2 (en) * | 2008-01-30 | 2013-02-06 | Ｈｏｙａ株式会社 | Optical glass, glass gob for press molding, optical element, manufacturing method thereof, and manufacturing method of optical element blank |
| CN102757168B (en) * | 2011-04-27 | 2016-01-27 | Hoya株式会社 | Precise punch forming preformed glass part manufacture method and Optical element manufacturing method |
| JP2014043355A (en) * | 2012-08-24 | 2014-03-13 | Nippon Electric Glass Co Ltd | Glass preform manufacturing method, and glass preform manufacturing device |
| JP2013010688A (en) * | 2012-08-30 | 2013-01-17 | Hoya Corp | Optical glass, glass gob for press-molding, optical element and method for producing the same, and method for producing optical element blank |
| JP5323278B2 (en) * | 2013-05-30 | 2013-10-23 | Ｈｏｙａ株式会社 | Optical glass, glass gob for press molding, optical element, manufacturing method thereof, and manufacturing method of optical element blank |
| CN121085518A (en) * | 2024-06-07 | 2025-12-09 | 维达力科技股份有限公司 | Glass devices and their preparation methods, molding apparatus |
| CN120398387B (en) * | 2025-05-19 | 2025-10-31 | 济宁海富光学科技有限公司 | A nanocrystalline glass pressing and molding machine for electronic optical cover plates |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5322541A (en) * | 1991-03-28 | 1994-06-21 | Matsushita Electric Industrial Co., Ltd. | Method of producing glass blank |
| CN1244508C (en) * | 1998-12-09 | 2006-03-08 | Hoya株式会社 | Method and device for mould pressing glass products |
| JP3945995B2 (en) * | 2001-05-01 | 2007-07-18 | Ｈｏｙａ株式会社 | Glass lump manufacturing method, glass lump forming apparatus, glass molded product manufacturing method, and optical element manufacturing method |
| US20050172671A1 (en) * | 2002-06-26 | 2005-08-11 | Hoya Corporation | Methods of manufacturing molded glass articles |
-
2006
- 2006-08-04 JP JP2006213113A patent/JP4368368B2/en not_active Expired - Fee Related
- 2006-09-27 CN CN2006101399495A patent/CN1939850B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1939850A (en) | 2007-04-04 |
| CN1939850B (en) | 2011-12-07 |
| JP2007119335A (en) | 2007-05-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP3853622B2 (en) | Manufacturing method of glass molded body, manufacturing method of press-molded product, manufacturing method of glass optical element, and manufacturing apparatus of glass molded body | |
| CN101397183A (en) | Precision mould-pressing forming performing member, forming mould, optical element and production method thereof | |
| JPH08259242A (en) | Flotation softening method for glass material, manufacture of optical device and optical device | |
| JP2004339039A (en) | Optical element manufacturing method | |
| JP4368368B2 (en) | Manufacturing method of glass lump, manufacturing apparatus thereof, and manufacturing method of optical element | |
| JPH09132417A (en) | Glass optical element molding method | |
| JP4309859B2 (en) | Method for manufacturing press-molding preform and method for manufacturing optical element | |
| CN102583972B (en) | Glass prefabricated member through precision impact molding manufacture method and Optical element manufacturing method | |
| JPH0471853B2 (en) | ||
| JP4460339B2 (en) | Mold press molding apparatus and optical element manufacturing method | |
| JP4684014B2 (en) | Precision press molding preform manufacturing method and optical element manufacturing method | |
| JP5654383B2 (en) | Manufacturing method of glass preform for precision press molding and manufacturing method of optical element | |
| JP3630829B2 (en) | Manufacturing method of optical element molding material | |
| JP5345228B2 (en) | Manufacturing method of glass preform for precision press molding and manufacturing method of optical element | |
| CN102757168A (en) | Method for producing preset-shaped glass member for precision stamping molding and method for producing optical element | |
| JP4289716B2 (en) | Glass element molding method | |
| JPH08133758A (en) | Production of glass optical element | |
| US20100162762A1 (en) | Optical element manufacturing method and optical element | |
| JP2000233934A (en) | Method for press-forming glass product and device therefor | |
| JP3243219B2 (en) | Method for manufacturing glass optical element | |
| JP5197696B2 (en) | Precision press molding preform manufacturing method and optical element manufacturing method | |
| JP5018503B2 (en) | Molten glass droplet miniaturized member, glass gob manufacturing method, and glass molded body manufacturing method | |
| JP2007099529A (en) | Preform for precision press molding, manufacturing method thereof, and manufacturing method of optical element | |
| JP2011057515A (en) | Glass gob and method for manufacturing glass molding | |
| JP2008074636A (en) | Method and device for producing optical element |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20090415 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20090512 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20090702 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20090825 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20090825 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 4368368 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120904 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130904 Year of fee payment: 4 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| LAPS | Cancellation because of no payment of annual fees |