JP5198347B2 - A method for producing a precision press-molding preform and a method for producing a glass optical element. - Google Patents
A method for producing a precision press-molding preform and a method for producing a glass optical element. Download PDFInfo
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- 239000011521 glass Substances 0.000 title claims description 124
- 238000000465 moulding Methods 0.000 title claims description 76
- 230000003287 optical effect Effects 0.000 title claims description 47
- 238000004519 manufacturing process Methods 0.000 title claims description 23
- 239000000463 material Substances 0.000 claims description 102
- 238000000227 grinding Methods 0.000 claims description 41
- 238000000034 method Methods 0.000 claims description 29
- 238000005498 polishing Methods 0.000 claims description 18
- 239000011159 matrix material Substances 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 2
- 238000003303 reheating Methods 0.000 description 6
- 230000005499 meniscus Effects 0.000 description 5
- 239000006060 molten glass Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 229910001018 Cast iron Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 239000005304 optical glass Substances 0.000 description 2
- 229910052582 BN Inorganic materials 0.000 description 1
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 229910001315 Tool steel Inorganic materials 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000006082 mold release agent Substances 0.000 description 1
- 238000007517 polishing process Methods 0.000 description 1
- 239000005401 pressed glass Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007788 roughening Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
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Description
本発明は、ガラス母材の研削、研磨工程を経てガラス製光学素子や精密プレス成形用プリフォームを製造するための精密プレス成形用プリフォームの製造方法、及びガラス製光学素子の製造方法に関する。 The present invention relates to a method for manufacturing a precision press-molding preform for manufacturing a glass optical element and a precision press-molding preform through a glass base material grinding and polishing process , and a method for manufacturing a glass optical element.
球面レンズなどのガラス製光学素子の製法として、光学ガラスからなるガラス素材を作り、このガラス素材を加熱、軟化し、プレス成形型に供給してプレス成形し、得られた成形品（光学素子母材）に荒ずり、砂かけ、研磨、芯取りといった加工を施し、最後に必要に応じて反射防止膜などのコーティングを行う方法が知られている。光学素子母材は、光学素子ブランクとも呼ばれ、光学素子の形状に近似し、光学素子の形状に研削、研磨によって除去される取りしろを加えた光学ガラス製の成形体である。 As a method of manufacturing a glass optical element such as a spherical lens, a glass material made of optical glass is produced, this glass material is heated and softened, and supplied to a press mold and press molded. There is known a method in which a material is processed such as roughening, sanding, polishing, and centering, and finally a coating such as an antireflection film is applied as necessary. The optical element base material is also called an optical element blank, and is a molded body made of optical glass that approximates the shape of the optical element and adds a margin that is removed by grinding and polishing to the shape of the optical element.
上記製造工程のうち、ガラス素材を加熱、軟化し、プレス成形して光学素子母材を生産する方法が、特許文献１に記載されている。
上記プレス成形法は、溶融ガラスを成形して得られたガラスを加工してガラス素材を作り、このガラス素材を再度、加熱、軟化してプレス成形することから再加熱プレス成形法あるいはリヒートプレス成形法と呼ばれている。
Among the manufacturing processes described above, Patent Document 1 discloses a method of heating and softening a glass material and press-molding it to produce an optical element base material.
In the above press molding method, the glass obtained by molding molten glass is processed to make a glass material, and this glass material is again heated and softened and then press molded, so that the reheat press molding method or reheat press molding is used. It is called the law.
再加熱プレス成形法は、特許文献２に記載されている精密プレス成形法あるいはモールドオプティクス成形法と比べ、プレス成形時のガラスの粘度が低いため、プレスによってガラスを変形させやすく成形時間を短くできるなどのメリットがある。また、プレス成形後、光学機能面を研削、研磨しない精密プレス成形法と異なり、プレス成形品の表面を加工によって除去するため、粉末状の離型剤の使用が可能になる。 Compared with the precision press molding method or the mold optics molding method described in Patent Document 2, the reheat press molding method has a lower glass viscosity at the time of press molding, so that the glass can be easily deformed by pressing and the molding time can be shortened. There are merits such as. Further, unlike the precision press molding method in which the optical functional surface is not ground or polished after press molding, the surface of the press molded product is removed by processing, so that a powdery mold release agent can be used.
しかしながら、再加熱プレス成形法で成形したレンズ母材の光学機能面に仕上げられる２つの面のうち、第１の面を荒ずり加工する際、第１の面に対向する第２の面またはコバに相当するレンズ母材の側面を研削加工機に精度よく固定する必要がある。 However, when roughing the first surface of the two surfaces finished on the optical functional surface of the lens base material molded by the reheating press molding method, the second surface or edge facing the first surface is used. It is necessary to accurately fix the side surface of the lens base material corresponding to to the grinding machine.
具体的には、上記第２の面もしくは側面を位置決め基準面とし、この位置決め基準面を研削加工機のワークホルダーの位置決め基準面に当接させた状態でレンズ母材を前記ホルダーに固定する。
その際、第２の面と側面の交わる部分に成形ばり（後述する図２参照）などの突起があるとレンズ母材をワークホルダーに正確に位置決め固定することができない。
あるいは、レンズ母材をワークホルダーに固定する際に母材の突起が破損し、ガラスの破片がワークホルダーの位置決め基準面を損傷させて、以後、正確な位置決め固定を困難にするという問題が発生したり、ＣＧ加工（カーブジェネレータによる球面研削加工）の刃具を損傷させる問題が発生することがあった。
Specifically, the second surface or side surface is used as a positioning reference surface, and the lens base material is fixed to the holder in a state where the positioning reference surface is in contact with the positioning reference surface of the work holder of the grinding machine.
At this time, if there is a projection such as a molding beam (see FIG. 2 described later) at a portion where the second surface and the side surface intersect, the lens base material cannot be accurately positioned and fixed to the work holder.
Or, when fixing the lens base material to the work holder, the protrusion of the base material breaks, and a piece of glass damages the positioning reference surface of the work holder, making it difficult to accurately position and fix thereafter. Or a problem of damaging the blade of CG processing (spherical grinding using a curve generator) may occur.
再加熱プレス成形法は、精密プレス成形法と比較し、ガラスを低粘度でプレスするため、上下型と胴型の間のクリアランス部にガラスが進入して上記突起が生じやすい。しかも、精密プレス成形法とは異なり、成形後に光学機能面を研削、研磨する必要があり、最初の荒ずり工程における位置決め固定を精密に行わなくてはならないという事情から、精密プレス成形法には存在しない上記特有の課題を解決しなければならない。 Since the reheat press molding method presses the glass with a lower viscosity than the precision press molding method, the glass tends to enter the clearance portion between the upper and lower molds and the barrel mold, and the protrusions are likely to occur. Moreover, unlike the precision press molding method, it is necessary to grind and polish the optical functional surface after molding, and because the positioning and fixing in the first roughing process must be performed precisely, the precision press molding method is The above unique problem that does not exist must be solved.
以上、レンズ母材を例にとり説明したが、同様の課題は、再加熱プレス成形法により精密プレス成形用プリフォームの母材を作製し、研削、研磨してプリフォームを作製する場合にも存在する。 The lens base material has been described above as an example, but the same problem exists when a preform for precision press molding is prepared by reheating press molding, and then the preform is prepared by grinding and polishing. To do.
本発明は上記事情のもとになされたものであり、研削、研磨加工に適したガラス母材、すなわち、光学素子母材やプリフォーム母材を、再加熱プレス成形法を用いて製造する方法、および前記方法で作製したガラス母材を用いて精密プレス成形用プリフォームやガラス製光学素子を製造する方法を提供することを目的とする。 The present invention has been made under the above circumstances, and is a method for producing a glass base material suitable for grinding and polishing, that is, an optical element base material and a preform base material, using a reheating press molding method. Another object of the present invention is to provide a method for producing a precision press-molding preform and a glass optical element using the glass base material produced by the above method.
本発明は、上記課題を解決するための手段として、
（１）ガラス母材を研削、研磨してガラス製光学素子を製造するにあたり、
胴型と、前記胴型に嵌め込まれた状態で互いに対向してガラス素材をプレスする上型と下型とを備え、かつ、前記胴型の前記上型が嵌め込まれる部分の内径よりも前記下型が嵌め込まれる部分の内径が小さいプレス成形型を用い、粘度が１０ ６ ｄＰａ・ｓ以下になるように加熱、軟化したガラス素材をプレス成形型内に導入し、プレス成形することにより前記ガラス母材を作製し、
前記ガラス母材を、下型成形面および／または胴型成形面によって成形された面を位置決め基準面として研削装置に固定し、上型成形面によって成形された面を所望の曲率になるよう球面研削加工する工程を備えることを特徴とするガラス製光学素子の製造方法、
（２）ガラス母材を研削、研磨して、ガラス製光学素子を精密プレス成形するための精密プレス成形用プリフォームを製造するにあたり、
胴型と、前記胴型に嵌め込まれた状態で互いに対向してガラス素材をプレスする上型と下型とを備え、かつ、前記胴型の前記上型が嵌め込まれる部分の内径よりも前記下型が嵌め込まれる部分の内径が小さいプレス成形型を用い、粘度が１０ ６ ｄＰａ・ｓ以下になるように加熱、軟化したガラス素材をプレス成形型内に導入し、プレス成形することにより前記ガラス母材を作製し、
前記ガラス母材を、下型成形面および／または胴型成形面によって成形された面を位置決め基準面として研削装置に固定し、上型成形面によって成形された面を所望の曲率になるよう球面研削加工する工程を備えることを特徴とする精密プレス成形用プリフォームの製造方法、。
（３）上記（２）項に記載の方法で精密プレス成形用プリフォームを作製し、前記精密プレス成形用プリフォームを加熱して精密プレス成形するガラス製光学素子の製造方法、
を提供する。
As a means for solving the above problems, the present invention provides:
(1) In manufacturing a glass optical element by grinding and polishing a glass base material,
A body mold, and an upper mold and a lower mold that press the glass material facing each other in a state of being fitted into the body mold , and the inner diameter of a portion of the body mold into which the upper mold is fitted is lower than Using a press mold having a small inner diameter at the part into which the mold is fitted , a glass material heated and softened so as to have a viscosity of 10 6 dPa · s or less is introduced into the press mold, and the glass mother is formed by press molding. Make the material,
The glass base material is fixed to a grinding device using a surface formed by the lower mold forming surface and / or the body mold forming surface as a positioning reference surface, and the surface formed by the upper mold forming surface is a spherical surface having a desired curvature. the method of manufacturing glass optical element characterized that you comprising the step of grinding,
(2) In manufacturing a precision press molding preform for grinding and polishing a glass base material and precision press molding a glass optical element,
A body mold, and an upper mold and a lower mold that press the glass material facing each other in a state of being fitted into the body mold, and the inner diameter of a portion of the body mold into which the upper mold is fitted is lower than the glass matrix by the inner diameter of the portion the mold is fitted into using small press mold, heated to a viscosity of below 10 6 dPa · s, introducing a glass material softened in the pressing mold in, press-molded Make the material,
The glass base material is fixed to a grinding device using a surface formed by the lower mold forming surface and / or the body mold forming surface as a positioning reference surface, and the surface formed by the upper mold forming surface is a spherical surface having a desired curvature. A method for producing a precision press-molding preform, comprising a grinding step.
(3) A method for producing a glass optical element, wherein a precision press-molding preform is prepared by the method described in (2) above, and the precision press-molding preform is heated to perform precision press molding .
I will provide a.
本発明によれば、ガラス母材を再加熱プレス成形法を用いて作製する際に、その下型成形面によって成形された面の外周の成形ばりを抑制して研削、研磨加工に適したガラス母材を作製することができ、作製したガラス母材を用いて精密プレス成形用プリフォームやガラス製光学素子を製造するにあたり、下型成形面および／または胴型成形面によって成形された面を位置決め基準面として研削装置に固定し、上型成形面によって成形された面を所望の曲率になるよう球面研削加工する工程を支障なく行うことができる。 According to the present invention, when a glass base material is produced by using a reheat press molding method, glass suitable for grinding and polishing by suppressing molding burr on the outer periphery of the surface formed by the lower mold forming surface. When producing a preform for precision press molding and a glass optical element using the produced glass preform, the surface formed by the lower mold molding surface and / or the barrel molding surface is used. The step of fixing to the grinding device as a positioning reference surface and performing spherical grinding so that the surface formed by the upper mold forming surface has a desired curvature can be performed without any trouble .
本発明において、光学素子母材とは研削、研磨によって光学素子を作製するための母材となるガラス物品であり、光学素子の形状に研削、研磨によって除去する取りしろを加えた形状を有するガラス物品のことを意味する。光学素子母材は光学素子ブランクとも呼ばれる。また、プリフォーム母材とは研削、研磨によって精密プレス成形用プリフォームを作製するための母材となるガラス物品であり、精密プレス成形用プリフォームの形状に研削、研磨によって除去する取りしろを加えた形状を有するガラス物品のことを意味する。 In the present invention, the optical element base material is a glass article that is a base material for producing an optical element by grinding and polishing, and has a shape obtained by adding a margin to be removed by grinding and polishing to the shape of the optical element. Means an article. The optical element base material is also called an optical element blank. A preform base material is a glass article that is a base material for producing a precision press-molding preform by grinding and polishing, and an allowance to be removed by grinding and polishing to the shape of the precision press-molding preform. It means a glass article having an added shape.
研削、研磨に要する手間、時間、コストを低減する上から、光学素子母材は光学素子の形状に近似する形状に成形することが好ましく、プリフォーム母材は精密プレス成形用プリフォームの形状に近似する形状に成形することが好ましい。
また、本発明において、光学素子母材およびプリフォーム母材をあわせてガラス母材と呼ぶ。
From the viewpoint of reducing labor, time and cost required for grinding and polishing, it is preferable to mold the optical element base material into a shape that approximates the shape of the optical element, and the preform base material has the shape of a precision press-molding preform. It is preferable to mold into an approximate shape.
In the present invention, the optical element base material and the preform base material are collectively referred to as a glass base material.
本発明では、ガラス製光学素子またはガラス製光学素子を精密プレス成形するための精密プレス成形用プリフォームを、研削、研磨により製造するためのガラス母材を、胴型と、前記胴型に嵌め込まれた状態で互いに対向してガラス素材をプレスする上型と下型とを備え、かつ、前記胴型の前記上型が嵌め込まれる部分の内径よりも前記下型が嵌め込まれる部分の内径が小さいプレス成形型を用い、加熱、軟化したガラス素材をプレス成形型内に導入し、プレス成形することにより作製する。 In the present invention, the precision press-molding preform for precision press molding glass optical elements or glass optical element, grinding, the glass preform for the production by polishing, and the body type, the barrel die An upper die and a lower die that press the glass material opposite to each other in the fitted state , and the inner diameter of the portion into which the lower die is fitted is larger than the inner diameter of the portion into which the upper die of the barrel die is fitted. Using a small press mold, the glass material heated and softened is introduced into the press mold and press molded .
プレス成形型内に導入するガラス素材は、ガラスの粘度が１０６ｄＰａ・ｓ以下になるように加熱、軟化することが望まれる。 It is desirable that the glass material introduced into the press mold is heated and softened so that the viscosity of the glass is 10 6 dPa · s or less.
図１は、本発明の実施形態の一例を示したものであり、プレス成形時、成形品の光軸となる軸、すなわち、プレス軸の中心軸を含む断面を模式的に示したものである。図２は改良前のもの、図１は本発明の一形態に相当する。
図２のプレス成形型は上型１´、下型２´、胴型３´によって構成される。図２では上型１´、下型２´ともに胴型３´内に嵌め込まれている様子が示されているが、最初に胴型３´内に下型２´を嵌め込み、上型１´は胴型３´から抜いた状態で、下型成形面上に加熱、軟化したガラス素材を導入する。次いで、上型１´を胴型３´内に嵌め込んで上下型１´、２´でガラス素材をプレスし、上下型成形面と胴型３´で囲まれた空間にガラスを押し広げる。
FIG. 1 shows an example of an embodiment of the present invention, and schematically shows a cross section including an axis that becomes an optical axis of a molded product at the time of press molding, that is, a center axis of a press shaft. . FIG. 2 corresponds to an embodiment before improvement, and FIG. 1 corresponds to an embodiment of the present invention.
The press mold of FIG. 2 includes an upper mold 1 ′, a lower mold 2 ′, and a body mold 3 ′. FIG. 2 shows that both the upper mold 1 ′ and the lower mold 2 ′ are fitted into the trunk mold 3 ′. First, the lower mold 2 ′ is fitted into the trunk mold 3 ′, and then the upper mold 1 ′. In a state of being removed from the body mold 3 ', a heated and softened glass material is introduced onto the lower mold forming surface. Next, the upper mold 1 ′ is fitted into the body mold 3 ′, the glass material is pressed by the upper and lower molds 1 ′, 2 ′, and the glass is spread in a space surrounded by the upper and lower mold forming surfaces and the body mold 3 ′.
図２より明らかなように胴型内径は任意の位置で一定であり、胴型３´に嵌め込まれる部分における上型１´および下型２´の外径は互いに等しくなっている。
図２では、ガラス素材をプレスするとガラスが押し広げられて、その先端部が胴型３´に到達した後、上型１´と胴型３´の間のクリアランス、下型２´と胴型３´の間のクリアランスに進入して成形ばりが生じやすい。
As is clear from FIG. 2, the inner diameter of the body mold is constant at an arbitrary position, and the outer diameters of the upper mold 1 ′ and the lower mold 2 ′ are equal to each other in the portion fitted into the body mold 3 ′.
In FIG. 2, when the glass material is pressed, the glass is spread and the tip reaches the body mold 3 ′, and then the clearance between the upper mold 1 ′ and the body mold 3 ′, the lower mold 2 ′, and the body mold A forming beam is likely to enter the clearance between 3 '.
このようにして成形したガラス母材をカーブジェネレータで球面加工するが、球面加工ではガラス母材の２つの面、すなわち、上型成形面で成形した面（第１の面）と下型成形面で成形した面（第２の面）のうち、一方の面を加工し、次いで他方の面を加工する。研削加工機、すなわちカーブジェネレータによる球面研削加工では、球面加工を行う面の反対側の面もしくは側面をワークホルダーに当接した状態でガラス母材を前記ホルダーに固定する。
その際、第１の面と側面の交わる部分と第２の面と側面の交わる部分の両方に成形ばりなどの突起が存在すると、ガラス母材を高精度にワークホルダーに位置決め固定することができない。あるいは突起が破損し、その破片がワークホルダーの位置決め基準面を損傷させるなどの問題もおきる。
The glass base material molded in this way is processed into a spherical surface by a curve generator. In spherical processing, two surfaces of the glass base material, that is, a surface formed by the upper mold forming surface (first surface) and a lower mold forming surface are used. Of the surface (second surface) formed in step 1, one surface is processed, and then the other surface is processed. In spherical grinding by a grinding machine, that is, a curve generator, the glass base material is fixed to the holder in a state where the surface or side surface opposite to the surface on which spherical machining is performed is in contact with the work holder.
At that time, if projections such as a forming beam are present at both the portion where the first surface and the side surface intersect and the portion where the second surface and the side surface intersect, the glass base material cannot be positioned and fixed to the work holder with high accuracy. . Or, the projection breaks, and the broken piece damages the positioning reference surface of the work holder.
一方、図１に示すプレス成形型は、胴型３の上型１が嵌め込まれる部分の内径よりも下型２が嵌め込まれる部分の内径を小さくすることにより、下型２と胴型３のクリアランス部にガラスが進入しにくい構造にしてある。上型１、下型２、胴型３などのプレス成形型構成部材間へのガラスの進入は、低粘度のガラスが加圧された状態でクリアランスの入り口に到達することによって始まる。ガラスがクリアランスの入り口に到達しても粘度が上昇していればクリアランスへの進入はおこりにくい。上下型１、２でプレスされてガラスは、上下型成形面との接触面積を増加させつつ横方向に伸び、その先端が胴型３に到達する。プレスされたガラスは上下型１、２、胴型３に接触すると熱伝導によって熱を奪われ、接触部分が急冷されて粘度が急速に上昇する。胴型３に到達したガラスの粘度も上昇する。胴型３の上型１が嵌め込まれる部分の内径よりも下型２が嵌め込まれる部分の内径を小さくしているため、ガラスが最初に胴型３に達する位置と、胴型３と下型２のクリアランス部入り口とを離すことができ、前記クリアランス部入り口に達するガラスは、胴型３によって十分熱を奪われて粘度が上昇しているため、クリアランス部に進入しない。 On the other hand, the press mold shown in FIG. 1 has a clearance between the lower mold 2 and the trunk mold 3 by making the inner diameter of the portion into which the lower mold 2 is fitted smaller than the inner diameter of the portion into which the upper mold 1 is fitted. It has a structure in which glass is difficult to enter. The entrance of the glass between the press mold components such as the upper mold 1, the lower mold 2, and the body mold 3 starts when the low viscosity glass is pressed and reaches the clearance entrance. Even if the glass reaches the clearance entrance, if the viscosity increases, it is difficult to enter the clearance. The glass pressed by the upper and lower molds 1 and 2 extends in the lateral direction while increasing the contact area with the upper and lower mold forming surfaces, and the tip reaches the barrel mold 3. When the pressed glass comes into contact with the upper and lower molds 1 and 2 and the body mold 3, heat is taken away by heat conduction, the contact portion is rapidly cooled, and the viscosity rapidly increases. The viscosity of the glass that reaches the barrel mold 3 also increases. Since the inner diameter of the part into which the lower mold 2 is fitted is made smaller than the inner diameter of the part into which the upper mold 1 of the trunk mold 3 is fitted, the position where the glass first reaches the trunk mold 3, the trunk mold 3 and the lower mold 2 The glass reaching the clearance portion entrance is sufficiently deprived of heat by the barrel mold 3 and has increased in viscosity, so that the glass does not enter the clearance portion.
一方、上型１と胴型３のクリアランス部の入り口は、ガラスの先端が最初に胴型３に到達する位置から離れていないため、前記クリアランス部にガラスが進入して成形ばりになることはある。
しかし、成形ばりが生じたとしても、ガラス母材の第1の面の周辺に限られるため、ガラス母材を上記ワークホルダーに位置決め固定する際に支障を来たすことはない。
さらに、プレス成形型内にガラス素材を導入し、成形後はプレス成形品を型内から取り出すため、上型１は胴型３から着脱自在な構造にすることが求められる。また、プレス成形品も胴型３からスムーズに取り出せるよう、上型１を嵌め込む部分の胴型３の内径をプレス成形品の最大外径と等しくするか、前記胴型３の内径を大きくする。
On the other hand, the entrance of the clearance part between the upper mold 1 and the body mold 3 is not separated from the position where the tip of the glass first reaches the body mold 3, so that the glass enters the clearance part and becomes a forming beam. is there.
However, even if a forming beam occurs, it is limited to the periphery of the first surface of the glass base material, so that there is no problem in positioning and fixing the glass base material to the work holder.
Furthermore, in order to introduce a glass material into the press mold and take out the press-molded product from the mold after molding, the upper mold 1 is required to have a structure that is detachable from the body mold 3. Further, the inner diameter of the body mold 3 where the upper mold 1 is fitted is made equal to the maximum outer diameter of the press-molded product or the inner diameter of the body mold 3 is increased so that the press-molded product can be smoothly taken out from the body mold 3. .
このような構成にすることにより、胴型３を一つの部材で構成することができ、胴型構造を単純化することができるとともに、胴型３の精度を高精度に保ちやすくなる。
なお、胴型３の上型１を嵌め込む部分から下型２を嵌め込む部分に向けて、胴型３の内径をステップ状に縮径してもよいし、連続的に縮径してもよい。
By adopting such a configuration, the trunk mold 3 can be composed of a single member, the trunk mold structure can be simplified, and the precision of the trunk mold 3 can be easily maintained with high accuracy.
It should be noted that the inner diameter of the barrel mold 3 may be reduced stepwise from the portion where the upper mold 1 is fitted to the portion where the lower mold 2 is fitted, or may be continuously reduced. Good.
胴型３の上型１を嵌め込む部分の内径φＵは、胴型３に嵌め込む部分の上型１の外径にほぼ等しく、胴型３の下型２を嵌め込む部分の内径φＬは、胴型３に嵌め込む部分の下型２の外径にほぼ等しい。ただし、胴型３内で上下型１、２を摺動するため、上型１の外径、下型２の外径を上記部分の胴型３の内径より僅かに小さくしておく。こうした関係から、本発明では胴型３に嵌め込む部分の上型外径を、胴型３に嵌め込む部分の下型外径より大きくする。 The inner diameter φ U of the portion into which the upper mold 1 of the trunk mold 3 is fitted is substantially equal to the outer diameter of the upper mold 1 of the section to be fitted into the trunk mold 3, and the inner diameter φ L of the portion into which the lower mold 2 of the trunk mold 3 is fitted. Is substantially equal to the outer diameter of the lower mold 2 of the portion fitted into the body mold 3. However, since the upper and lower molds 1 and 2 slide in the body mold 3, the outer diameter of the upper mold 1 and the outer diameter of the lower mold 2 are made slightly smaller than the inner diameter of the body mold 3 in the above portion. From this relationship, in the present invention, the upper die outer diameter of the portion fitted into the trunk mold 3 is made larger than the lower die outer diameter of the portion fitted into the trunk mold 3.
φＵ−φＬは、プレス成形品、すなわちガラス母材の大きさ、形状によって適宜決めればよいが、φＵ−φＬを１ｍｍ以上とすることがガラス母材の第２の面側の成形ばり発生を抑制する上で好ましい。ただし、φＵ−φＬを大きく取りすぎると光学素子母材では第２の面の光学機能面を確保できなくなり、プリフォーム母材では精密プレス成形における被プレス面を確保できなくなるため、φＬは目的とする光学素子の光学機能面の直径以上、目的とするプリフォームの被プレス面の直径以上とすることが望ましい。φＵ−φＬの上限としては３０ｍｍを目安に考えればよい。 φ U −φ L may be appropriately determined depending on the size and shape of the press-formed product, that is, the glass base material. However, if φ U −φ L is set to 1 mm or more, the second surface side of the glass base material is molded. It is preferable for suppressing the occurrence of flash. However, phi U when -.phi L too take greater can not be secured to the optical functional surface of the second surface is an optical element matrix, it becomes impossible to secure the target press surface in precision press molding preform preform, phi L It is desirable that the diameter be equal to or larger than the diameter of the optical functional surface of the target optical element and equal to or larger than the diameter of the target preform pressed surface. The upper limit of φ U −φ L may be considered with 30 mm as a guide.
図１に示すプレス成形型構造を用いることにより、第２の面の外周の成形ばりを抑制することができ、次工程におけるガラス母材の位置決め固定を支障なく行うことができる。
なお、再加熱プレス成形法で使用するプレス成形型材としては鋳鉄、ステンレス鋼、耐熱鋼、工具鋼などを用いることができ、プレス成形条件としては公知の条件を適宜適用することができる。
By using the press mold structure shown in FIG. 1, it is possible to suppress the forming flash on the outer periphery of the second surface, and it is possible to perform positioning and fixing of the glass base material in the next process without any trouble.
Note that cast iron, stainless steel, heat-resistant steel, tool steel, and the like can be used as a press mold used in the reheat press molding method, and known conditions can be appropriately applied as press molding conditions.
こうして得たガラス母材を、上型１を胴型３から外し、取り出し、アニールして歪を低減する。ガラス母材を光学素子母材とする場合は、アニールによって屈折率を所望の値に精密に一致させることが好ましい。 The glass base material thus obtained is removed from the upper mold 1 from the body mold 3, taken out, and annealed to reduce strain. When the glass base material is used as the optical element base material, it is preferable to precisely match the refractive index with a desired value by annealing.
図１に示すプレス成形型を用いて成形したガラス母材の胴型３によって成形された面（ガラス母材の側面）、第２の面が球面研削工程における位置決め基準面となり得る。前述のようにワークホルダーにガラス母材を位置決め固定し、カーブジェネレータで第１の面を所望の曲率に球面研削加工する。第１の面の外周に成形ばりが存在していたとしても、この加工により成形ばりが除去され、さらに次の工程で第１の面を位置決め基準面として用いても成形ばりによる支障は生じない。 The surface (side surface of the glass base material) formed by the glass base material cylinder 3 formed using the press mold shown in FIG. 1 and the second surface can serve as a positioning reference surface in the spherical grinding step. As described above, the glass base material is positioned and fixed to the work holder, and the first surface is spherically ground to a desired curvature with a curve generator. Even if a molding beam exists on the outer periphery of the first surface, the molding beam is removed by this processing, and even if the first surface is used as a positioning reference surface in the next step, there is no problem due to the molding beam. .
同様にして第２の面を球面研削加工した後、砂かけ、研磨の各工程を経て光学素子または精密プレス成形用プリフォームを作ることができる。
得られたプリフォームを加熱し、精密プレス成形して非球面レンズを作製することができる。
得られた光学素子には反射防止膜などを適宜コートしてもよい。
Similarly, after the second surface is subjected to spherical grinding, an optical element or a precision press-molding preform can be produced through the steps of sanding and polishing.
The obtained preform can be heated and precision press molded to produce an aspheric lens.
The obtained optical element may be appropriately coated with an antireflection film or the like.
（実施例１）
所望の光学特性が得られるように調合したガラス原料を坩堝内に導入し、加熱、溶融して溶融物を得、溶融物を清澄、均質化して溶融ガラスを得た。この溶融ガラスを鋳型に流し込んでブロック状に成形し、アニールした後に賽の目状に切断し、カットピースと呼ばれるガラス片を複数個作製した。
Example 1
A glass raw material prepared so as to obtain desired optical characteristics was introduced into a crucible, heated and melted to obtain a melt, and the melt was clarified and homogenized to obtain a molten glass. The molten glass was poured into a mold, formed into a block shape, annealed, and then cut into a square shape to produce a plurality of glass pieces called cut pieces.
次いで、カットピースをバレル研磨し、再加熱プレス成形法で作製しようとする母材の重量と等しいガラス素材になるように重量調整するとともに、表面を粗面化し、エッジの丸め加工を行った。 Next, the cut piece was barrel-polished, the weight was adjusted so as to be a glass material equal to the weight of the base material to be produced by the reheating press molding method, the surface was roughened, and the edge was rounded.
このようにして得たガラス素材の全表面に粉末状の窒化硼素を均一に塗布し、ガラス素材の粘度が１０５〜１０６ｄＰａ・ｓになるように加熱、軟化し、図１に示す鋳鉄製のプレス成形型を用い、球面凸メニスカスレンズ用母材を再加熱プレス成形法で作製した。 The powdered boron nitride is uniformly applied to the entire surface of the glass material thus obtained, heated and softened so that the viscosity of the glass material becomes 10 5 to 10 6 dPa · s, and cast iron shown in FIG. A base material for a spherical convex meniscus lens was manufactured by a reheating press molding method using a manufactured press molding die.
プレス成形型内へのガラス素材の導入にあたり、上型を胴型から外した状態で軟化したガラス素材を下型成形面の中央に導入した。次いで、上型を胴型に嵌め込んで、ガラス素材を上下型でプレスした。プレス圧力は１〜１０ＭＰａ、プレス時間は３〜８秒とした。 When the glass material was introduced into the press mold, the softened glass material was introduced into the center of the lower mold surface with the upper mold removed from the barrel mold. Next, the upper mold was fitted into the trunk mold, and the glass material was pressed with the upper and lower molds. The press pressure was 1 to 10 MPa, and the press time was 3 to 8 seconds.
次に、上型を上昇させてプレス成形品を上型から離型し、上型を胴型から外し、下型上のプレス成形品を取り出した。
取り出したプレス成形品は所望の凸メニスカスレンズ近似形状に成形されており、上型成形面で成形された第１の面の外周に成形ばりの発生は認められたものの、下型成形面で成形された第２の面の外周に成形ばりは全く認められなかった。
なお、本実施例では上型を嵌め込む部分の胴型の内径φＵを６０ｍｍ、下型を嵌め込む部分の胴型の内径φＬを４０ｍｍとした。
Next, the upper mold was raised, the press-molded product was released from the upper mold, the upper mold was removed from the barrel mold, and the press-molded product on the lower mold was taken out.
The removed press-molded product is molded in the approximate shape of the desired convex meniscus lens, and although molding was observed on the outer periphery of the first surface molded on the upper mold surface, it was molded on the lower mold surface. No forming flash was observed on the outer periphery of the second surface.
Incidentally, the inner diameter phi U body mold portions fitting the upper die 60 mm, and 40mm inner diameter phi L of the barrel-shaped portion fitting the lower mold in this embodiment.
プレス成形型から取り出したプレス成形品をアニールし、歪を低減するとともに屈折率を所望の値に精密に一致させ、第２の面を位置決め基準面としてカーブジェネレータのワークホルダーに精密に位置決め固定し、第１の面を所望の曲率になるよう球面研削加工した。 The press-molded product taken out from the press mold is annealed to reduce distortion and precisely match the refractive index to the desired value, and the second surface is used as a positioning reference surface to precisely position and fix it on the work holder of the curve generator. The first surface was subjected to spherical grinding so as to have a desired curvature.
次いで、第１の面を位置決め基準面としてワークホルダーに精密に位置決め固定し、第２の面を所望の曲率になるよう球面研削加工した。
なお、上記各球面研削加工において、ガラス母材の側面、すなわち胴型によって成形された面をワークホルダーに固定する際の位置決め基準面にしてもよいし、第１の面を球面研削加工する際、ガラス母材の第２の面および側面を位置決め基準面に用いてもよい。また、第２の面を球面研削加工する際、ガラス母材の第１の面および側面を位置決め基準面として用いてもよい。
Next, the first surface was precisely positioned and fixed to the work holder using the positioning reference surface, and the second surface was subjected to spherical grinding so as to have a desired curvature.
In each of the above spherical grinding processes, the side surface of the glass base material, that is, the surface formed by the body mold may be used as a positioning reference surface for fixing to the work holder, or when the first surface is subjected to the spherical grinding process. The second surface and the side surface of the glass base material may be used as the positioning reference surface. Further, when the second surface is subjected to spherical grinding, the first surface and the side surface of the glass base material may be used as the positioning reference surface.
このようにして成形ばりによる支障を来たすことなしにガラス素材の第１の面、第２の面の球面研削加工を行うことができた。 In this manner, spherical grinding of the first surface and the second surface of the glass material could be performed without causing trouble due to the forming beam.
（比較例）
次に、図２に示すプレス成形型を用いて実施例１と同様にガラス母材を再加熱プレス成形したところ、プレス成形品の第１の面と第２の面の外周に成形ばりが発生した。
(Comparative example)
Next, when the glass base material was reheat press-molded using the press mold shown in FIG. 2 in the same manner as in Example 1, a molding beam was generated on the outer periphery of the first surface and the second surface of the press-molded product. did.
（実施例２）
次に実施例１で作製した第１の面、第２の面が球面研削加工されたガラスを砂かけ、研磨し、さらに芯取り加工を行った球面凸メニスカスレンズを作製し、光学機能面に反射防止膜をコートした。
(Example 2)
Next, a spherical convex meniscus lens having a first surface and a second surface prepared in Example 1 that have been subjected to spherical grinding is sanded, polished, and subjected to centering processing to produce an optical functional surface. An antireflection film was coated.
（実施例３）
次に実施例１で作製した第１の面、第２の面が球面研削加工されたガラスを砂かけ、研磨し、さらに芯取り加工を行った球面凸メニスカスレンズ形状の精密プレス成形用プリフォームを作製した。このプリフォームの全表面に炭素膜をコートし、成形面に炭素膜をコートしたＳｉＣ製のプレス成形型内に導入し、プリフォームとプレス成形型を一緒に加熱し、精密プレス成形して非球面凸メニスカスレンズを得た。得られたレンズを芯取りした後、反射防止膜をコートした。
なお精密プレス成形の条件は公知の条件を用いた。
(Example 3)
Next, a precision convex molding preform having a spherical convex meniscus lens shape obtained by sanding, polishing, and centering a glass having a first surface and a second surface prepared in Example 1 that have been subjected to spherical grinding. Was made. The entire surface of this preform is coated with a carbon film, introduced into a SiC press mold with a carbon film coated on the molding surface, the preform and the press mold are heated together, and precision press molding is performed for non-molding. A spherical convex meniscus lens was obtained. The obtained lens was centered and then coated with an antireflection film.
The conditions for precision press molding were known conditions.
本発明によれば、研削、研磨加工に適した光学素子母材やプリフォーム母材などのガラス母材を、再加熱プレス成形法を用いて作製し、作製されたガラス母材を研削、研磨してガラス製光学素子や精密プレス成形用プリフォームを製造することができる。 According to the present invention, a glass base material such as an optical element base material and a preform base material suitable for grinding and polishing is produced using a reheating press molding method, and the produced glass base material is ground and polished. Thus, a glass optical element and a precision press-molding preform can be manufactured.
１、１´ 上型
２、２´ 下型
３、３´ 胴型
1, 1 'upper mold 2, 2' lower mold 3, 3 'body mold
Claims (7)
胴型と、前記胴型に嵌め込まれた状態で互いに対向してガラス素材をプレスする上型と下型とを備え、かつ、前記胴型の前記上型が嵌め込まれる部分の内径よりも前記下型が嵌め込まれる部分の内径が小さいプレス成形型を用い、粘度が１０ ６ ｄＰａ・ｓ以下になるように加熱、軟化したガラス素材をプレス成形型内に導入し、プレス成形することにより前記ガラス母材を作製し、
前記ガラス母材を、下型成形面および／または胴型成形面によって成形された面を位置決め基準面として研削装置に固定し、上型成形面によって成形された面を所望の曲率になるよう球面研削加工する工程を備えることを特徴とするガラス製光学素子の製造方法。 In manufacturing a glass optical element by grinding and polishing a glass base material,
A body mold, and an upper mold and a lower mold that press the glass material facing each other in a state of being fitted into the body mold , and the inner diameter of a portion of the body mold into which the upper mold is fitted is lower than Using a press mold having a small inner diameter at the part into which the mold is fitted , a glass material heated and softened so as to have a viscosity of 10 6 dPa · s or less is introduced into the press mold, and the glass mother is formed by press molding. Make the material,
The glass base material is fixed to a grinding device using a surface formed by the lower mold forming surface and / or the body mold forming surface as a positioning reference surface, and the surface formed by the upper mold forming surface is a spherical surface having a desired curvature. method of manufacturing a glass optical element characterized that you comprising the step of grinding.
胴型と、前記胴型に嵌め込まれた状態で互いに対向してガラス素材をプレスする上型と下型とを備え、かつ、前記胴型の前記上型が嵌め込まれる部分の内径よりも前記下型が嵌め込まれる部分の内径が小さいプレス成形型を用い、粘度が１０ ６ ｄＰａ・ｓ以下になるように加熱、軟化したガラス素材をプレス成形型内に導入し、プレス成形することにより前記ガラス母材を作製し、
前記ガラス母材を、下型成形面および／または胴型成形面によって成形された面を位置決め基準面として研削装置に固定し、上型成形面によって成形された面を所望の曲率になるよう球面研削加工する工程を備えることを特徴とする精密プレス成形用プリフォームの製造方法。 In manufacturing a precision press molding preform for grinding and polishing a glass base material to precisely press mold a glass optical element,
A body mold, and an upper mold and a lower mold that press the glass material facing each other in a state of being fitted into the body mold, and the inner diameter of a portion of the body mold into which the upper mold is fitted is lower than the glass matrix by the inner diameter of the portion the mold is fitted into using small press mold, heated to a viscosity of below 10 6 dPa · s, introducing a glass material softened in the pressing mold in, press-molded Make the material,
The glass base material is fixed to a grinding device using a surface formed by the lower mold forming surface and / or the body mold forming surface as a positioning reference surface, and the surface formed by the upper mold forming surface is a spherical surface having a desired curvature. A method for producing a precision press-molding preform, comprising a step of grinding.
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| JP2009105931A JP5198347B2 (en) | 2009-04-24 | 2009-04-24 | A method for producing a precision press-molding preform and a method for producing a glass optical element. |
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