JP2004292287A - Method of manufacturing glass optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of continuously and stably manufacturing a high precision optical glass element having excellent appearance quality. <P>SOLUTION: The method of continuously manufacturing the glass optical element is a method for press-molding the glass base materials softened by heating successively using a molding die. In the method, a simulation press molding is carried out using a glass base material (simulation glass base material) worked into a nearly the same shape and composed of a glass different from the regular glass base material under a condition equal to the press molding condition before the regular glass base material is press molded to obtain the desired optical element and after that the regular glass base material is molded. The simulation press molding is carried out using the simulation glass base material under the molding condition equal to the press molding condition using the regular glass base material every time when the press molding of the regular glass base material is carried out the prescribed number of times. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００５１】
［本発明の第２の態様］
（実施例５）
実施例１による成形後、同じ成形装置、及び本ガラス素材（光学ガラスＡ）を用いて、プレスを行ない、同様の形状の両凸レンズを成形した。成形工程は、実施例１と同様である。但し、下記に記載の方法にて、光学ガラスＡのガラス素材を５００回プレスする毎に、模擬ガラス素材ａを用いて１０回のプレス成形を行う方法にて連続して、ガラス素材の成形を行った。
【００５２】
このようにして得られたガラス成形体２（外径φ１８ｍｍ、肉厚２．９ｍｍ、両凸レンズ）のアニール後の性能を、干渉計による面精度と、目視外観及び実体顕微鏡による表面状態の２点について評価した結果、プレスショット数が２００００回までのいずれの成形体（レンズ）も良好なものであった。
【００５３】
（比較例２）
実施例５と同様にして、光学ガラスＡからなるガラス素材を連続して成形した。このようにして得られたガラス成形体２（外径φ１８ｍｍ、肉厚２．９ｍｍ、両凸レンズ）のアニール後の性能を、干渉計による面精度と、目視外観及び実体顕微鏡による表面状態の２点について評価した結果、プレスショット数が約８００回から、カン・ワレが、おおよそ、５００ショットにつき１回の率で発生し始め、プレスショット数が約２８００回から、外観品質が基準を下回る様になり、プレスは１２０００回で中止した。
【００５４】
（実施例６〜７）
ガラス素材および模擬ガラス素材の組成、予熱温度、型温度、模擬ガラス素材への着色剤および添加量を表２のとおり、変更した以外は実施例５と同様に、プレスによりガラス素子を成形した。このようにして得られたガラス成形体のアニール後の性能を、干渉計による面精度と、目視外観及び実体顕微鏡による表面状態の２点について評価した結果、プレスショット数が２００００回までのいずれの成形体（レンズ）も良好なものであった。
【００５５】
（実施例８）
本ガラス素材および模擬ガラス素材を実施例４と同様にし、実施例４の成形に続いて、同様の方法でプレスした。但し、本ガラス素材を５００回プレスする毎に１０回の模擬プレス成形を行う方法にて連続して、本ガラス素材の成形を行った。なお、この模擬ガラス素材は、着色剤であるＦｅ_２Ｏ_３を０．０１ｗｔ％添加し、青緑色に着色しており、ガラス素材および成形品において、模擬材は瞬時かつ確実に区別することができる。このようにして得られたガラス成形体のアニール後の性能を、干渉計による面精度と、目視外観及び実体顕微鏡による表面状態の２点について評価した結果、プレスショット数が２００００回までのいずれの成形体（レンズ）も良好なものであった。
【００５６】
【表２】

【００５７】
【表３】

【００５８】
【発明の効果】
以上のように、本発明の製造方法は、成形始動時に型面へのガラス融着やガラス成形体のカン・ワレを防ぎ、ガラス素材が融着やカン・ワレが発生し易いリン酸塩、フツリン酸塩やホウ酸塩を主成分とする場合または高屈折率成分である酸化チタン、酸化ニオブ、酸化タングステン、フッ素、塩素を含む場合でも、高い外観品質のガラス光学素子を短いタクトで大量に製造するために有効である。
【図面の簡単な説明】
【図１】成形型での押圧成形の概略説明図である。
【図２】成形型の下型の概略説明図である。
【図３】軟化したガラス素材の成形型（下型）への移送方法の概略説明図である。
【図４】軟化したガラス素材の成形型（下型）への移送方法の概略説明図である。
【図５】成形型での押圧成形の概略説明図である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a glass optical element such as a glass lens without grinding and polishing after press molding. In particular, the present invention relates to a method for manufacturing a glass optical element capable of stably manufacturing a glass optical element having high appearance quality.
[0002]
[Prior art]
2. Description of the Related Art A method of manufacturing a glass optical element such as a glass lens without performing grinding and polishing after press molding has been widely used. However, depending on the type of the glass material to be press-molded, fusion with the molding surface or cracking may easily occur. As described above, in the case of pressing and molding a glass material in which fusion or cracking is likely to occur, various proposals have been made to provide a coating on the glass material surface and the mold surface in order to prevent fusion and cracking. I have.
[0003]
For example, Patent Document 1 (Japanese Patent Publication No. 2-31012) discloses a method of preventing fusion between glass and a mold by forming a carbon film on at least one of mutually facing surfaces of the glass and the mold. Is described. Patent Document 2 (Japanese Patent Application Laid-Open No. 2002-348127) discloses that glass is formed by coating a surface of a glass material for molding with an oxide comprising at least one element selected from Mn, Fe, Co, Ni, and Cr. A method for preventing fusion between the mold and the mold is described. Also, Patent Document 3 (Japanese Patent No. 2583593) discloses a method of cleaning a molding die by molding a predetermined number of glass glass materials having a higher transition point than the glass material to be molded without changing the temperature of the molding die. Is described.
[0004]
[Patent Document 1] Japanese Patent Publication No. 2-31012
[Patent Document 2] JP-A-2002-348127
[Patent Document 3] Japanese Patent No. 2583593
[0005]
[Problems to be solved by the invention]
According to the method described in Patent Document 1, a certain effect can be seen in suppressing glass fusion to a mold. However, in the case of molding in which the molding cycle time is shortened, a glass optical element that satisfies all conditions such as maintaining the appearance quality cannot be obtained. For example, in a continuous press exceeding 5,000 shots, it was inevitable that the appearance quality deteriorated due to generation of cracks and clouding and scratches on the glass optical element surface. In particular, if the molded optical element breaks at the time of mold release, there is a great obstacle to production, such as the need to stop the process and remove fragments.
[0006]
In the technique described in Patent Document 2, when an oxide is coated on the surface of a glass material, a step of peeling off an oxide film on the surface of a molded product is newly required, and there is a problem that the cost is increased.
In the technique described in Patent Document 3, it is necessary to mold a glass material having a high transition point with a low temperature molding die. For this reason, physical damage such as scratches occurs on the mold surface and the release film surface, and problems such as deterioration of appearance quality and deterioration of release film wear occur in subsequent molding.
[0007]
In view of the above problems, an object of the present invention is to provide a method for continuously and stably producing a high-precision optical glass element having excellent appearance quality. In particular, it is an object of the present invention to provide a method capable of manufacturing a high-precision optical glass element having excellent appearance quality while preventing cracking even when using glass made of a glass type that is easily broken. Further, the present invention is a so-called non-isothermal press in which a glass material having a higher temperature than the mold is supplied to the mold and press-molded, and a molding method in which the mold is released at a relatively high temperature (for example, around Tg). Even if it exists, it aims at providing the method which can perform a press molding stably and can manufacture a highly accurate optical glass element continuously.
[0008]
[Means for Solving the Problems]
As a result of a detailed analysis and investigation by the present inventors, the following has become clear.
For the mold used to press-mold the glass material, the surface after the mold processing, or the surface after the release film is formed on the mold, such as the bond forcibly cut by processing or film formation, There are physically or chemically active structures. In addition, the structure having such high activity may be regenerated on the molding surface of the molding die after the press molding is stopped due to the temperature decrease, volatilization and the like of the die. For this reason, the surface of the mold or the release film in the early stage of molding tends to react with the glass material. As a result, the mold surface or a part of the release film formed on the mold surface is consumed, or the glass material is likely to be damaged by being fused to the mold surface or the release film formed on the mold surface. Yes, this tendency is particularly large at the beginning of molding. As a result, in the subsequent continuous molding, the appearance quality of the optical element to be molded is deteriorated and cracks occur due to damage caused on the mold surface and the release film in the initial stage of the molding.
[0009]
In addition to the surface after the mold processing or after the release film was formed on the mold, it was also found that the following phenomena were observed when a large number of glass materials were continuously pressed and formed.
When a glass material is continuously pressed and formed, a small amount of components of the glass material are deposited on the surface of a mold or a release film, and the releasability from the glass material is gradually deteriorated. As a result, the glass is easily fused to the mold surface or the release film formed on the mold surface, and the glass is damaged such as a part of the mold surface or the release film formed on the mold surface is consumed. There is. Then, in the subsequent continuous molding, from the damage, the appearance quality is degraded, and cracking is caused.
[0010]
Therefore, a first aspect of the present invention is:
A method for continuously manufacturing a glass optical element by sequentially heating and softening a glass material by pressing using a molding die,
Prior to press-molding a glass material (real glass material) to obtain a desired optical element, a glass material (simulated glass material) that is processed into a shape substantially equal to the real glass material and made of glass different from the real glass material is used. Perform simulated press forming under the same forming conditions as press forming of this glass material using
Thereafter, the present glass material is subjected to press molding,
This is the manufacturing method.
A second aspect of the present invention provides:
A method for continuously manufacturing a glass optical element by sequentially heating and softening a glass material by pressing using a molding die,
Every time the glass material (the present glass material) is pressed and formed a predetermined number of times to obtain a desired optical element, the glass material is processed into a shape substantially equal to the present glass material and made of a glass different from the present glass material (simulated glass material). Using a glass material) to perform simulated press forming under the same forming conditions as the press forming of the present glass material.
This is the manufacturing method.
[0011]
In the first and second aspects of the present invention, the following aspects are preferred.
(1) The present glass material is a glass material containing a reducing or volatile component, and the simulated glass material is a glass material not containing these components.
(2) The molding conditions include preheating the molding die to a predetermined temperature, supplying the glass material heated to a temperature higher than the molding die and softened to the molding die, and immediately press-molding.
(3) The simulated glass material is made of glass having a deformation point within a range of a deformation point temperature ± 50 ° C. of the glass used for the present glass material.
(4) The present glass material is made of a fluorophosphate-based, phosphate-based, borate-based, or borate-based glass.
(5) The present glass material is made of a phosphate-based or fluorophosphate-based glass containing at least one of titanium oxide, niobium oxide, tungsten oxide, bismuth oxide, chlorine, and fluorine as a glass component.
(6) The simulated glass material is made of silicate glass or borosilicate glass.
(7) The simulation glass material is colored.
[0012]
Furthermore, the present invention relates to a glass material used as a simulated glass material in a method of manufacturing a glass optical element by pressing a glass material that has been heated and softened by using a molding die.
[0013]
Hereinafter, the first embodiment of the present invention will be described.
A first aspect of the present invention is a method for continuously manufacturing a glass optical element by successively press-molding a heat-softened glass material using a mold.
In the first aspect of the present invention, prior to press molding of the present glass material, the present glass material is processed into a shape substantially equal to the present glass material, and the present glass material is pressed by using a simulated glass material different from the present glass material. Simulated press forming is performed under the same forming conditions as the forming, and then the present glass material is pressed to continuously form an optical element.
[0014]
According to the study of the present inventors, it has been clarified that the occurrence of the damage of the release film in the early stage of the molding strongly depends on the molding temperature and the composition of the glass material, and the higher the molding temperature is, the larger the damage is. At the same molding temperature, the intensity of damage at the initial stage of molding is as follows: silicate glass <borosilicate glass << borate glass <borophosphate glass <phosphate glass <fluorophosphate system. It was also found that the order was glass.
[0015]
As is clear from the above ranking, the glass material is made of glass containing a phosphate or borate as a main component, such as a fluorophosphate-based glass, a phosphate-based glass, a borate-based glass, and a borate-based glass. In such a case, a part of the mold surface or the release film formed on the mold surface in the early stage of molding is consumed, or the glass is damaged by being fused to the mold surface or the release film formed on the mold surface. easy. As a result, in the subsequent continuous molding, the appearance quality is degraded, and cracking occurs due to the damage at the initial stage of molding. In particular, this tendency is remarkable in a fluorophosphate-based glass and a phosphate-based glass.
[0016]
In particular, when the present glass material is, for example, P ₂ O ₅ 12-34%, B ₂ O ₃ Containing 0.2 to 15% (indicated by mol%), in particular, P ₂ O ₅ And B ₂ O ₃ In the case where the total content of is from 15 to 35%, part of the mold surface or the release film formed on the mold surface in the early stage of molding was consumed, or glass was formed on the mold surface or the mold surface. It is susceptible to damage such as fusion to the release film.
[0017]
More specifically, in mole%, P ₂ O ₅ 12-34%, B ₂ O ₃ 0.2-15%, Nb ₂ O ₅ 0-25%, WO ₃ 0-40% and Li ₂ O, Na ₂ O and K ₂ At least one R ′ selected from O ₂ A glass material containing 0 to 30% (not including 30%) of at least one RO selected from O4 to 45% and BaO, ZnO and SrO, and having a total content of the above components of 94% or more, In the early stage of molding, the mold surface or a part of the release film formed on the mold surface is easily consumed, and the glass is easily damaged by fusing to the mold surface or the release film formed on the mold surface.
[0018]
Therefore, when the present glass material is the above-described glass, in the first aspect of the present invention, at the time of starting molding, the simulated glass material is molded at least until the molding apparatus is stabilized, thereby reducing damage at the initial molding. It can relax and prevent appearance quality deterioration and cracking in subsequent continuous molding. The simulated glass material is selected from the glass materials having a low intensity of damage at the initial stage of molding from the above-mentioned order, and the present glass material is made of a phosphate glass such as a fluorophosphate glass and a phosphate glass. In this case, the simulated glass material is preferably selected from glasses containing no phosphate.
[0019]
Similarly, when the present glass material is a glass containing any of titanium oxide, niobium oxide, tungsten oxide, chlorine, and fluorine, the mold surface or the release film on the mold surface is easily damaged in the early stage of molding. Therefore, it is preferable to form the simulated glass material at least until the forming apparatus is stabilized. At this time, it is preferable to use a glass material not containing these components as the simulated glass material. In the first embodiment of the present invention, particularly when the present glass material is pressed using a high refractive index, high dispersion optical glass having a refractive index nd of 1.6 or more and an Abbe number νd of 35 or less, Especially effective. These glass materials often contain titanium oxide, niobium oxide, tungsten oxide, or bismuth oxide, which is a reducing component. Further, it is effective for optical glass having a refractive index nd of 1.75 or more and an Abbe number νd of 20 to 28.5.
Further, when molding a low refractive index, low dispersion glass optical element, chlorine or fluorine which is a volatile component may be contained, but the present invention is also suitable for such a glass material.
[0020]
In the present invention, a molding operation is performed with a simulated glass material that does not damage the mold surface or the release film formed on the mold surface under the same conditions as the molding conditions of the present glass material at the time of starting the press. Here, the molding conditions include conditions of molding temperature and molding pressure. As a result, the active state of the surface of the mold surface or the release film formed on the mold surface is significantly reduced, and the reactivity and adhesion between the glass and the release film formed on the mold surface or the mold surface are improved. This significantly reduces the releasability. It is considered that this is because the formation of the simulated glass material has a function of reducing active sites such as a mold surface or an unbonded end of a release film. For this reason, at the time of molding with the present glass material, it is possible to prevent melting and cracking to the mold surface.
[0021]
Further, as the simulation glass material, a glass material processed into a shape substantially equal to the present glass material is used. Therefore, the simulated glass material has substantially the same volume as the present glass material. Further, the molding conditions of the simulated glass material are substantially the same as the molding conditions of the present glass material. Thereby, it is possible to shift to press molding to the present glass material without loss in a process such as a change in press conditions, and thereafter, the present glass material can be formed stably. As described above, as the composition of the simulated glass material, a composition having a smaller initial damage strength than the present glass material is selected. In addition, the number of times of molding with the simulated glass material can be appropriately determined in consideration of the activation state of the surface of the mold surface or the release film formed on the mold surface, and at least the molding apparatus is stabilized (the activity of the molding surface decreases. Until the reproducibility of the pressing conditions is obtained). The molding of the simulated glass material is usually preferably performed 5 times or more, more preferably 10 times or more. Thereby, the active state of the molding surface of the mold is stabilized, and a predetermined effect can be obtained. Substantially 20 times or less is sufficient for forming the simulated glass material.
[0022]
The simulated glass material can be molded under the same conditions as the molding of the present glass material, and does not cause cracking on the mold surface or the mold surface. Is selected from glass materials that cause less damage to the glass material. From such a viewpoint, it is preferable that a silicate such as a silicate glass or a borosilicate glass contains the largest amount of a silicate as a glass component. Preferred glass as the simulated glass material is, for example, SiO 2 ₂ Is preferably contained in an amount of 30 to 55% by weight. ₂ O ₃ From 5 to 30 wt%, and SiO ₂ And B ₂ O ₃ Having a total content of 56 to 70 wt% is preferred. As described above, it is preferable that the material does not contain titanium oxide, niobium oxide, tungsten oxide, fluorine, and chlorine.
[0023]
The simulated glass material preferably has a forming temperature range substantially the same as the glass used for the present glass material. This is because the simulated glass material can be pressed under substantially the same molding conditions as the present glass material. Thus, after forming the simulated glass, the present glass material can be formed without changing the conditions. Specifically, it is preferable that the sagging point temperature of the simulated glass material has a sagging point (Ts) in a range of ± 50 ° C. with respect to the sagging point temperature of the present glass material. More preferably, the sagging point temperature of the simulated glass material has a sagging point (Ts) in a range of ± 15 ° C. with respect to the sagging point temperature of the present glass material. The Tg (transition point) of the simulated glass material is also preferably within a range of ± 50 ° C. with respect to the Tg of the present glass material.
[0024]
The press of the simulated glass material in the first embodiment of the present invention is performed immediately after starting the press forming of the present glass material after the mold processing or after the release film is formed on the mold surface, without changing the forming conditions. The glass material is preferably formed. This is because, by changing the molding conditions (temperature, pressing pressure) before the main glass molding, the activity of the molding surface is newly increased, and the reproducibility of various conditions brought to the glass material is impaired. In addition, immediately after processing and film formation, the press device can be stabilized by pressing the simulated glass material even after the press device is stopped and when press molding is started.
[0025]
Next, a second embodiment of the present invention will be described.
A second aspect of the present invention is a method for continuously manufacturing a glass optical element by sequentially press-molding a heat-softened glass material using a molding die.
In the second aspect of the present invention, every time the press molding of the present glass material is performed a predetermined number of times, using a simulated glass material made of a glass different from the present glass material, under the same molding conditions as the press molding of the present glass material. Simulated press molding is performed. Here, the molding conditions include the molding temperature and the molding pressure. That is, press molding is performed using a simulated glass material that causes less damage to the mold surface or the release film formed on the mold surface every predetermined number of times of the press molding of the glass optical element. It is appropriate that the number of times of press molding using the simulated glass material is performed until the mold releasability of the mold is restored to a predetermined state.
[0026]
Press molding with a simulated glass material removes a small amount of glass material components deposited on the mold surface or the release film formed on the mold surface, and recovers the mold releasability to some extent or to the same level as before press molding (Refresh). When the releasability is recovered, the reactivity and adhesion between the glass and the mold surface or the release film formed on the mold surface are significantly reduced, and cracking can be prevented.
[0027]
The simulated glass material is a glass material processed into a shape substantially equal to the present glass material, as in the first embodiment. Therefore, the simulated glass material has substantially the same volume and substantially the same shape as the present glass material, and can be formed under the same conditions. The transfer can be performed, and thereafter, the present glass material can be formed stably. The simulated glass material is selected from glasses having a glass composition having a smaller damage strength than the present glass material. Further, the simulated press molding is performed every predetermined number of times of the press molding of the present glass material, and the frequency of the simulated press molding is, for example, preferably every 1000 times of the press molding of the present glass material, and more preferably every 500 times. The number of times the simulated glass material is pressed in the simulated press molding can be appropriately determined in consideration of the degree of mold release, and is, for example, preferably 5 or more, more preferably 10 or more. The upper limit of the number of times the simulated glass material is pressed is not particularly limited, and can be appropriately determined in consideration of the degree of recovery of the mold releasability, and is, for example, about 20 times.
[0028]
As the present glass material and the simulated glass material applied in the second embodiment of the present invention, those similar to the first embodiment of the present invention can be used.
[0029]
When manufacturing an actual glass optical element, it is preferable to use the first and second aspects of the present invention together.
[0030]
Hereinafter, matters common to the first and second aspects of the present invention will be described.
The manufacturing method of the present invention is a method of manufacturing a glass optical element by press-molding a heat-softened glass material with a preheated mold, or a glass material and a mold in a state where the glass material is introduced into the mold. The present invention can be applied to a method for manufacturing a glass optical element by heating and pressing. In particular, the present invention is suitable for a press method in which a glass material is preheated to a temperature higher than the mold temperature, and then supplied to the mold and immediately subjected to press molding. For example, with a glass viscosity of 10 ⁹ Temperature corresponding to less than Poise, preferably 10 ⁶ -10 ⁸ A glass material with a temperature equivalent to poise ⁸ -10 ¹² It can be supplied to a mold heated to a temperature corresponding to poise to perform press molding. At this time, heat exchange occurs instantaneously between the high-temperature glass supplied to the molding die and the mold surface, and the mold surface or the release film provided on the mold is easily damaged, so that glass fusion or fusion occurs. There is a strong tendency that the appearance quality is deteriorated due to consumption of the release film, and that cracking is increased. Therefore, the effect of the present invention is remarkably obtained. In supplying the glass material to the molding die, it is preferable that the glass material be transported in a floating state by an air current and supplied to the mold. This is because the heat-softened glass material easily causes a surface defect due to contact with a transport jig or the like.
[0031]
In particular, the production method of the present invention is to soften the glass material by heating it while floating by air flow, and transfer the heated and softened glass material to a preheated mold by dropping it, and then press molding immediately. The present invention can be applied to a method for manufacturing a glass optical element. The cooling of the formed glass material is started after or simultaneously with the start of the press forming, and the mold can be released at a temperature around Tg. At this time, the release temperature was set to 10 ¹² -10 ^13.5 Preferably, the temperature is equivalent to poise. This is advantageous in shortening the cycle time, and since the present invention suppresses cracking, a good product can be obtained efficiently.
[0032]
The simulated glass material is preferably colored. The simulated glass material can be molded under substantially the same volume and under the same conditions as the glass material, so that the molding of the simulated glass material can be continuously shifted to the molding of the glass material. In this case, there is a possibility that a molded product of the simulated glass material and a molded product of the present glass material are mixed. Further, the present glass material and the simulated glass material may be mixed. Therefore, it is desired that by coloring the simulated glass material, the glass material and the simulated glass material, and the molded product of the simulated glass material and the molded product of the glass material can be instantaneously and reliably distinguished.
[0033]
As a method of coloring the simulated glass material, it is necessary to use a method that does not cause damage at the initial stage of molding and a method that does not lose color by molding. Further, it is preferable not to cause contamination or damage to the apparatus in the production of the simulated glass material. From such a viewpoint, as a method of coloring the simulated glass material, a method of adding a coloring agent to the glass raw material is preferable. As the coloring additive, for example, oxides of Fe, Cr, Co, Ni, Mn, and Cu are preferable, and Fe, Cr, and Ni are particularly preferable. The amount of the coloring additive is preferably 0.1% by weight or less. Preferably, it is in the range of 0.005 to 0.05 wt%.
[0034]
The present invention encompasses a colored glass material, which is used as a simulated glass material in a method of manufacturing a glass optical element by press-molding a heat-softened glass material using a molding die.
[0035]
As a mold base material used in the present invention, for example, SiC, WC, TiC, TaC, BN, TiN, AlN, Si ₃ N ₄ , SiO ₂ , Al ₂ O ₃ , ZrO ₂ , W, Ta, Mo, cermet, sialon, mullite, carbon composite (C / C), carbon fiber (CF), WC-Co alloy, glass material including crystallized glass, stainless heat-resistant metal, etc. Materials can be used effectively. The mold preferably has a release film on the molding surface. Further, as the release film, a film containing carbon as a main component is preferable in terms of effect and cost. Examples of the film containing carbon as a main component include a diamond-like carbon film (hereinafter, DLC), a hydrogenated diamond-like carbon film (hereinafter, DLC: H), and a tetrahedral amorphous carbon film (hereinafter, ta-C). A carbon-based film selected from a hydrogenated tetrahedral amorphous carbon film (hereinafter, ta-C: H), an amorphous carbon film (hereinafter, aC), a hydrogenated amorphous carbon film (hereinafter, aC: H), and the like. Can be mentioned. Such a release film may be formed by a CVD method, a DC-plasma CVD method, an RF-plasma CVD method, a microwave plasma CVD method, an ECR-plasma CVD method, an optical CVD method, a laser CVD method, in addition to a vacuum deposition method, a sputtering method, or the like. A film can be appropriately formed by a known method such as a plasma CVD method such as a method, an ionization evaporation method such as an ion plating method, a sputtering method, an evaporation method, and an FCA method. Preferably, a sputtering method or an ion plating method is used. In addition, as the release film, for example, Si ₃ N ₄ , TiAlN, TiCrN, CrN, Cr _X N _Y , AlN, TiN or other nitride coating or composite multilayer film or laminated film (AlN / CrN, TiN / CrN, etc.), Pt-Au, Pt-Ir-Au, Pt-Rh-Au Those containing an alloy coating can also be applied. The thickness of the release film can be, for example, 0.1 nm to 1000 nm.
[0036]
Further, the glass material applied to the present invention is preferably provided with a carbon-containing layer on the surface for the purpose of releasing or slipping. For forming the carbon-containing layer, a vapor deposition method using a carbon material, a method of depositing carbon on the surface of a glass material by thermal decomposition of a hydrocarbon, or the like can be used as appropriate. The thickness of the carbon-containing layer on the glass material is preferably 0.1 to 10 nm.
The layer containing carbon can be provided not only on the present glass material but also on a simulated glass material.
[0037]
Examples of the optical element manufactured by the manufacturing method of the present invention include a lens, a prism, a mirror, a grating, a microlens, a laminated diffraction grating, and the like, and there is no particular limitation. The manufacturing method of the present invention is suitable for manufacturing an optical lens having at least one aspheric surface. The shape of the optical element can be, for example, a biconvex, convex meniscus lens, biconcave, concave meniscus lens, etc., and in particular, a biconvex lens having a small wall thickness around the periphery or a concave meniscus lens having a small center wall thickness. The manufacturing method of the present invention is effective for manufacturing a biconcave lens. This is because the glass optical element having the above shape is most liable to bend and crack. The use of the optical element manufactured by the manufacturing method of the present invention is not particularly limited, and examples thereof include an imaging system lens for a camera (including a video camera, a digital camera, a camera with a built-in mobile terminal, and the like), an optical pickup lens, and the like. is there. In particular, it is suitably used for a camera imaging system using an optical glass having a high refractive index, a high dispersion, a low refractive index, and a low dispersion.
[0038]
【Example】
Next, the present invention will be described in more detail with reference to examples.
[First embodiment of the present invention]
(Example 1)
Press mold
As shown in FIG. 2, the press-molding die uses a silicon carbide (SiC) sintered body 31 as a base material, processes it into a press-molding die shape by grinding, and further forms a silicon carbide film 32 on the molding surface side by a CVD method. Was formed and further ground and polished to a shape corresponding to a glass molded body to be produced, thereby obtaining a molding die. Further, an i-carbon film 33 is formed on the silicon carbide film 32 of the mold by 500 [deg.] By ion plating to form a lower mold 34 for a bi-convex glass lens having a molding surface 40 and a diameter of 18 mm (15 mm after centering). Obtained. The upper mold 35 shown in FIG. 1 was also obtained by the same method as the lower mold 34 described above. As shown in FIG. 1, the upper mold 35 and the lower mold 34 are set coaxially, and at the time of press molding, a molding mold 39 is composed of the upper mold 35, the lower mold 34, and the guide mold 36 that guides them. Have been. The lower mold 34 and the upper mold 35 are heated by a mold heater 44 attached to the outer periphery of the body mold 37, and controlled by two thermocouples 42 for temperature measurement inserted into the lower mold 34 and the upper mold 35. . Further, the temperature of the shell mold 37 is measured by a shell-type temperature measuring thermocouple 43 inserted in each of the upper mold and the lower mold 37.
[0039]
Floating jig
In a closed chamber (not shown) having the above-described mold heating mechanism, a floating jig 10 (10a, 10b), a guide means 50 (50a, 50b) shown in FIG. A heater (not shown) is provided. The floating jig 10 is a divided floating jig made of glassy carbon (hereinafter, referred to as a GC divided floating jig), and the guide means 50 is also a divided cylindrical guide made of the same material (hereinafter, referred to as a GC divided cylindrical guide). is there. Further, the glass material 1 is supplied with 200% to 600 ml / min of 98% N supplied from the inside of the GC divided floating jig. ₂ + 2% H ₂ It is levitated and held by the jet of gas.
[0040]
Genuine glass material and simulated glass material
The present glass material of this embodiment is made of a phosphate optical glass A. Before forming the glass material, the glass material can be press-molded under the same conditions as the glass material. After the press molding was performed 10 times by the method described below, the present glass material was continuously molded. Table 3 shows the composition, glass transition temperature, and yield point of the present glass material A and the simulated glass material a. As a molding device, a molding die after the formation of the i-carbon film was used. The simulated glass material used was a coloring agent Fe ₂ O ₃ Is added in an amount of 0.01% by weight and colored blue-green, so that the simulated glass material can be instantaneously and reliably distinguished between the glass material and the molded product.
[0041]
Heat softening and pressing process
After evacuating the inside of the closed chamber of the molding machine containing the above-mentioned press forming mechanism (FIGS. 1 and 2) and the glass heating mechanism (FIG. 3), 98% N ₂ + 2% H ₂ Gas was introduced, and the inside of the closed chamber was set to the same gas atmosphere. Next, the molding die heater 44 shown in FIG. 1 is heated until the temperature (mold temperature) of the upper mold 35 and the lower mold 34 measured with the thermocouple 42 for mold temperature (mold temperature) reaches 550 ° C. and is maintained at the same temperature. did. At this time, the upper mold and the lower mold are separately heated at different positions, and are assembled as an integral mold as shown in FIG. 1 during molding. On the other hand, the temperature (preheating temperature) of the glass material 1 on the GC divided floating jig 10 is heated and maintained at 650 ° C. by the glass softening heater.
[0042]
Next, the GC divided floating jig 10 which floats and holds the heat-softened glass material 1 quickly moves to immediately above the lower mold 34, and then, as shown in FIG. 4, the GC divided floating jig 10a and the GC divided floating jig. The glass material 1 is dropped and placed on the molding surface 40 of the lower die 34 by instantaneously moving and opening each of the right and left horizontal directions. At this time, a GC divided cylindrical guide 50 having an inner diameter dimension that maintains an appropriate clearance with respect to the outermost diameter of the glass material 1 is installed directly above the GC divided floating jig 10. When the jig 10 is opened and the glass material 1 falls, it serves as a guide for minimizing the amount of setting deviation between the glass material 1 and the lower mold 34.
[0043]
After the glass material falls, the GC divided cylindrical guide 50a and the other 50b move in the left and right horizontal directions to open. Therefore, there is no obstacle at the upper part of the lower mold 34, and the molding die support 38 instantaneously rises to the upper mold 35 where the lower mold 34 is fixedly set together with the molding die support 38 above the lower mold 34. Then, as shown in FIG. 1, the glass material 1 was placed in a molding die composed of an upper die 35 and a guide die 36 for guiding the lower die 34 at a rate of 100 kg / cm for 10 seconds. ² Then, the mold heater is pressurized to a predetermined thickness, and then the mold heater is turned off. Furthermore, the glass molded body and the mold were allowed to cool, and after 70 seconds, the temperatures of the upper mold 35 and the lower mold 34 measured by the thermocouple 43 for mold temperature measurement became 420 ° C. to 450 ° C. near the glass transition point. When the temperature reached ° C, the glass molded body was released from the mold and taken out.
[0044]
The annealed performance of the glass molded body (outside diameter φ18 mm, wall thickness 2.9 mm, biconvex lens) obtained in this manner was evaluated for surface accuracy by an interferometer, visual appearance, and surface state by a stereomicroscope. As a result of evaluation, any molded product (lens) having a number of press shots of up to 8000 was satisfactory without any cans and cracks.
[0045]
(Comparative Example 1)
In the same manner as in Example 1, a glass material of the optical glass A was formed from the start of pressing. The annealed performance of the glass molded body (outside diameter φ18 mm, wall thickness 2.9 mm, biconvex lens) obtained in this manner was evaluated for surface accuracy by an interferometer, visual appearance, and surface state by a stereomicroscope. As a result of the evaluation, from the number of press shots of about 800, perception of cracking began to occur at a rate of approximately once per 200 shots, and from the number of press shots of about 2000, the visual appearance and the surface evaluated by a stereomicroscope. The condition fell below the standard for appearance quality, and the press was stopped after 2000 times.
[0046]
(Examples 2-3)
A glass element was formed by pressing in the same manner as in Example 1 except that the composition of the glass material and the simulated glass material, the preheating temperature, the mold temperature, the colorant and the amount added to the simulated glass material were changed as shown in Table 1. The performance of the glass molded body obtained in this way after annealing was evaluated for two points of surface accuracy by an interferometer, visual appearance, and surface state by a stereomicroscope. The molded article (lens) was also good.
[0047]
(Example 4)
Glass material and simulated glass material
The glass material of the present embodiment is an optical glass A, and before molding of the present glass material, a borosilicate-based simulated glass material a which can be press-molded under the same conditions as the present glass material is subjected to the following method. After the press molding was performed 10 times, the present glass material was continuously molded. Note that this simulated glass material is made of Fe, which is a coloring agent. ₂ O ₃ Was added in an amount of 0.01% by weight and colored blue-green, so that the simulation material could be instantaneously and reliably distinguished between the glass material and the molded product.
[0048]
This glass material was placed in a forming apparatus shown in FIG. 5 and heated to 590 ° C. in a nitrogen gas atmosphere to 150 kg / cm 2. ² Pressure for 1 minute. After releasing the pressure, cooling was performed at a cooling rate of −50 ° C./min to 480 ° C., and thereafter, cooling was performed at a rate of −200 ° C./min or more, and the temperature of the press-formed product dropped to 200 ° C. or less. Thereafter, the glass molded body was taken out. As a molding die, a polycrystalline SiC produced by a CVD method is mirror-polished to Rmax = 18 nm, and then a DLC: H film is formed on the molding surface by using an ion plating method film forming apparatus as a release film. Was used.
[0049]
The annealed performance of the glass molded body (outside diameter φ12 mm, wall thickness 1.2 mm, biconvex lens) obtained in this manner was evaluated for surface accuracy by an interferometer, visual appearance, and surface state by a stereomicroscope. As a result of the evaluation, any molded product (lens) having a number of press shots of up to 8000 was good without any cans and cracks.
[0050]
[Table 1]

[0051]
[Second embodiment of the present invention]
(Example 5)
After forming according to Example 1, pressing was performed using the same forming apparatus and the present glass material (optical glass A) to form a biconvex lens having a similar shape. The molding process is the same as in the first embodiment. However, each time the glass material of the optical glass A is pressed 500 times by the method described below, the molding of the glass material is continuously performed by a method of performing the press molding 10 times using the simulated glass material a. went.
[0052]
The performance after annealing of the glass molded body 2 (outside diameter φ18 mm, wall thickness 2.9 mm, biconvex lens) obtained in this manner was evaluated by measuring the surface accuracy with an interferometer, the visual appearance, and the surface state with a stereomicroscope. As a result of evaluation, all the molded articles (lenses) having a number of press shots of up to 20,000 times were good.
[0053]
(Comparative Example 2)
In the same manner as in Example 5, a glass material made of the optical glass A was continuously formed. The annealed performance of the glass molded body 2 (outside diameter φ18 mm, wall thickness 2.9 mm, biconvex lens) obtained in this manner was evaluated for the surface accuracy using an interferometer, the visual appearance, and the surface state using a stereomicroscope. As a result of the evaluation, the number of press shots starts to be generated at about 800 times, and the occurrence of can-wales starts to occur at a rate of approximately once per 500 shots. The press was stopped at 12,000 times.
[0054]
(Examples 6 and 7)
A glass element was formed by pressing in the same manner as in Example 5, except that the composition of the glass material and the simulated glass material, the preheating temperature, the mold temperature, the colorant and the amount added to the simulated glass material were changed as shown in Table 2. The performance of the glass molded body thus obtained after annealing was evaluated for surface accuracy by an interferometer, visual appearance, and surface state by a stereomicroscope. The molded article (lens) was also good.
[0055]
(Example 8)
The present glass material and the simulated glass material were made in the same manner as in Example 4, and pressed in the same manner as in Example 4, following the molding. However, each time the present glass material was pressed 500 times, the present glass material was continuously formed by a method of performing simulated press forming 10 times. Note that this simulated glass material is made of Fe, which is a coloring agent. ₂ O ₃ Is added in an amount of 0.01% by weight and colored blue-green, so that the simulation material can be instantaneously and reliably distinguished between the glass material and the molded product. The performance of the glass molded body thus obtained after annealing was evaluated for surface accuracy by an interferometer, visual appearance, and surface state by a stereomicroscope. The molded article (lens) was also good.
[0056]
[Table 2]

[0057]
[Table 3]

[0058]
【The invention's effect】
As described above, the manufacturing method of the present invention prevents glass fusion to the mold surface and cracking of the glass molded body at the time of molding start, and the glass material is likely to cause fusion or cracking of the phosphate, Even if it contains fluoric acid or borate as a main component or contains high refractive index components such as titanium oxide, niobium oxide, tungsten oxide, fluorine and chlorine, a large amount of glass optical elements with high appearance quality can be produced in a short time. Effective for manufacturing.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of press molding with a molding die.
FIG. 2 is a schematic explanatory view of a lower mold of a molding die.
FIG. 3 is a schematic explanatory view of a method for transferring a softened glass material to a forming die (lower die).
FIG. 4 is a schematic explanatory view of a method for transferring a softened glass material to a forming die (lower die).
FIG. 5 is a schematic explanatory view of press molding with a molding die.

Claims (10)

A method for continuously manufacturing a glass optical element by sequentially heating and softening a glass material by pressing using a molding die,
Prior to press molding of a glass material (hereinafter, referred to as the present glass material) for obtaining a desired optical element, a glass material (hereinafter, referred to as a glass material) that is processed into a shape substantially equal to the present glass material and is made of glass different from the present glass material. Simulated press molding under the same molding conditions as the press molding of the present glass material using a simulated glass material)
Thereafter, the present glass material is subjected to pressure molding. A method for continuously manufacturing a glass optical element by sequentially heating and softening a glass material by pressing using a molding die,
Every time the glass material (hereinafter, referred to as the present glass material) is pressed and formed a predetermined number of times to obtain a desired optical element, the glass material is processed into a shape substantially equal to the present glass material, and is made of glass different from the present glass material. The method according to claim 1, wherein a simulated press forming is performed using a material (hereinafter, referred to as a simulated glass material) under the same forming conditions as the press forming of the present glass material. The production method according to claim 1 or 2, wherein the present glass material is a glass material containing a reducing or volatile component, and the simulated glass material is a glass material not containing these components. 4. The molding method according to claim 1, wherein the molding conditions include preheating the molding die to a predetermined temperature, supplying the glass material heated and softened to a temperature higher than the molding die to the molding die, and immediately pressing the glass material. The production method according to the paragraph. The method according to any one of claims 1 to 4, wherein the simulated glass material is made of glass having a deformation point within a range of a deformation point temperature of glass used for the present glass material ± 50 ° C. The production method according to any one of claims 1 to 5, wherein the glass material is made of a fluorophosphate-based, phosphate-based, borate-based, or borate-based glass. The glass material according to any one of claims 1 to 5, wherein the glass material is a phosphate-based glass containing at least one of titanium oxide, niobium oxide, tungsten oxide, bismuth oxide, chlorine, and fluorine, or a fluorophosphate-based glass. Item 2. The production method according to item 1. The method according to claim 1, wherein the simulated glass material is made of a silicate glass or a borosilicate glass. The method according to claim 1, wherein the simulated glass material is colored. A glass material used as a simulated glass material in a method of manufacturing a glass optical element by press-molding a colored glass material, which has been heated and softened, using a molding die.

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