JP3894643B2 - Method for fixing spherical mold in mold and mold - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for fixing a sphere in a mold used for press molding of a glass optical element, and a mold.
[0002]
[Prior art]
In recent years, a method of obtaining glass optical elements by press-molding heat-softened glass with a pair of molds is widely known.
[0003]
Of the glass optical elements, a molding die for molding a glass optical element having a spherical notch as an optical function surface is a convex surface portion whose molding surface is a molding function surface of the mold (referred to as a surface for molding an optical function surface). And a plane portion continuing from the convex surface portion. On the other hand, a molding die having a convex molding function surface close to a hemisphere is difficult to polish near the connecting portion between the convex surface portion and the flat portion when the molding die is manufactured. The entire surface could not be used as an optical function surface. In view of this point, a technique disclosed in Japanese Utility Model Laid-Open No. 63-94929 has been proposed as a molding die that can be satisfactorily obtained up to the connecting portion between the entire molding functional surface of the molding die and the flat portion. As illustrated in FIG. 5, the molding die 51 described in the above publication is a sphere in which a spherical center is located on the central axis of the molding die body 52 and a part of the spherical surface is a molding surface. 53 is arranged as a sphere 54, and this sphere 54 is pressed and fixed by the holder 55 from the outside of the sphere to the mold body 52 side. In the mold 51 having the above-described configuration, the mirror surface processing of the entire surface of the sphere 53 and the mirror surface processing of the flat surface portion 56 of the holder 55 can be easily and individually performed. Since the glass optical element is fixed, the connecting portion between the convex portion and the flat portion 56 can be molded well, and an optical contact is generated between the spherical 54 and the glass optical element when the glass optical element is taken out. However, since the spherical mold 54 is not separated from the mold main body 52 together with the glass optical element, the mold can be released satisfactorily.
[0004]
[Problems to be solved by the invention]
However, in the configuration described in the above publication, when the spherical shape is fixed by the holder from the outside of the spherical shape, the ridge line portion 57 where the holder 55 and the spherical shape 54 are in contact with each other is scratched circumferentially. It was necessary to carry out spherical polishing when using it again as a spherical shape.
Further, in the spherical fixing method using a holder, it is impossible to use a hemispherical surface as a spherical molding function surface in order to secure a region where the spherical shape is pressed by the holder.
[0005]
The present invention has been made in view of the above problems, and a spherical fixing method and a molding die that can be used up to a hemispherical surface as a spherical molding functional surface without scratching the spherical shape. The purpose is to provide.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a method for fixing a sphere in a molding die in which a sphere having a spherical surface with a part of a spherical surface as a molding surface is provided as a sphere. When the optical element is released from the spherical shape, the spherical shape is sucked and held on the mold body.
[0007]
The molding die according to claim 2 of the present invention is a molding die in which a spherical surface in which a part of the spherical surface is a molding surface is provided on the molding die body, and at least the surface transferred to the optical element is mirror-finished. A suction part having a spherical shape made of a sphere and sucking the spherical shape and holding it in the molding die main body when the concave receiving portion and the molded optical element are separated from the spherical shape so as to accommodate the spherical shape In the mold body.
The receiving part of the mold main body is preferably mirror-finished into a concave shape with the same radius of curvature as the spherical mold.
According to the configuration of the first or second aspect, the spherical mold is sucked and held on the mold body, so that it is not necessary to press and fix the molding function surface of the spherical sphere with a holder or the like. Therefore, there is no scratch on the spherical surface. Further, a hemispherical surface from which glass molded from the spherical shape can be taken out can be used as a spherical molding functional surface.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The concept of the mold used in the embodiment of the present invention will be described below with reference to FIG. In FIG. 1, a spherical mold 2 composed of a sphere 1 whose entire spherical surface is mirror-finished by ball polishing or the like is formed into a concave shape with the same radius of curvature as the spherical mold 2 and the concave surface is mirror-finished. It is placed on a receiving part 4 of a receiving mold 3 as a main body. The center of the receiving portion 4 of the receiving mold 3 is on the central axis of the receiving mold 3. In addition, the receiving mold 3 is provided with a suction section 5 that allows the spherical mold 2 placed on the receiving section 4 to be sucked. In the mold 6 having the above-described configuration, the spherical mold 2 placed on the receiving part 4 of the receiving mold 3 can be held on the receiving mold 3 by reducing the pressure via the suction part 5. Therefore, there is no room for scratches on the surface of the spherical mold 2 placed on the receiving portion 4 of the receiving mold 3, and any part of the spherical mold 2 can be used again as a molding functional surface of the spherical mold 2. Further, the spherical functional surface of the spherical mold 2 can be used up to a hemisphere.
(Embodiment 1) Embodiment 1 of the present invention will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view of a molding apparatus to which the present embodiment is applied when a meniscus lens is molded as a glass optical element. The same components as those in FIG. 1 will be described using the same reference numerals. In FIG. 2, a spherical mold 2 is composed of a WC (tungsten carbide) sphere 1 in which the entire spherical surface is mirror-finished by ball polishing. In this embodiment, WC is used as a material, but ceramics such as SiC, Al ₂ O ₃ , and AlN may be used, and a spherical surface is coated with a film such as Pt to make a mirror surface. Good. In the receiving mold 3 for mounting the spherical mold 2, the receiving section 4 for mounting the spherical mold 2 has a concave concave surface and is mirror-finished with the same radius of curvature as the spherical mold 2. The flat portion 7 around the concave shape is formed into a rough surface, and the flat portion around the optical function surface of the meniscus lens is formed into a rough surface. The receiving mold 3 is placed on a base 11 placed on a base 10. A suction port 12 serving as a suction portion that enables suction of the spherical mold 2 is formed in the central portion of the receiving mold 3, that is, coaxially with the central axis of the receiving mold 3. A suction pipe 14 having one end fixed to the hole formed in the hole and connected to a suction device such as a vacuum pump (not shown) is inserted into the other end. A cylindrical sleeve 15 into which the receiving mold 3 and the like are inserted and a cylindrical quartz tube 16 made of quartz glass that is longer than the sleeve 15 and is transparent than the sleeve 15 are placed on the table 11. Has been. In the sleeve 15, on the upper side facing the receiving mold 3 on which the spherical mold 2 is placed, the surface opposite to the surface formed by the spherical mold 2 and the receiving mold 3 among the optical function surfaces of the meniscus lens. As a mold for molding the upper mold 18, the upper mold 18 is arranged via the glass 20. The upper mold 18 is made of WC, and its molding surface is processed into a mirror surface by polishing, so that the inner surface of the sleeve 15 can slide when the glass 20 is molded. On the outside of the quartz tube 16, a heater (for example, an infrared heater) 19 for heating the inner spherical shape 2, the receiving die 3, the glass 20 and the upper die 18 via the sleeve 15 is arranged in a circular tube shape. . Further, on the outer side, a reflecting barrel 22 for reflecting infrared rays emitted from the heater 19 is disposed on the base 10, and the inner surface condenses the infrared rays on the central axis of the inner peripheral surface of the sleeve 15. Curvature is provided so that the inner peripheral surface is gold-plated in order to increase reflection efficiency. A lid-like upper base 21 is placed on the reflecting lens barrel 22. The upper base 21 includes a cylinder 25 having a cylinder rod 24 for pressurizing the upper mold 18, and a quartz tube 16. A pipe 26 for allowing the non-oxidizing gas to flow into is fixed. The lower side of the upper base 21 is set so as to be in contact with the upper end of the quartz tube 16, and the non-oxidizing gas flowing in from the pipe 26 is inserted into the quartz tube 16 and the gap between the quartz tube 16 and the base 11. Purge is performed so as to flow out of the gap between the quartz tube 16 and the upper base 21. A case where a meniscus lens is molded by the molding apparatus having the above configuration will be described. First, the upper base 21 is removed, and the spherical mold 2 is placed on the receiving portion 4 of the receiving mold 3 and inserted into the sleeve 15. The glass 20 is inserted into the sleeve 15 and placed on the spherical mold 2, and the upper mold 18 is inserted into the sleeve 15 to form a molding assembly 28. Next, the upper base 21 is placed on the reflecting lens barrel 22, and nitrogen gas is introduced as non-oxidizing gas from the pipe 26. When the gas is in a state in which oxidation of the mold or the like is prevented, heating of the molding assembly 28 is started by the heater 19. When the viscosity of the glass becomes 10 ^13.5 poise or less and fluidity is obtained, the cylinder 25 is operated and the glass 20 is pressurized via the cylinder rod 24. Next, after raising the cylinder rod 24 and separating the cylinder rod 24 from the upper mold 18, heating by the heater 19 is stopped and cooling of the formed glass 20 is started. After the glass 20 is cooled to room temperature, the gas inflow is stopped and the upper base 21 is removed. Next, the suction device 13 (not shown) is operated to decompress the inside of the suction port 12 and the suction pipe 14, and the spherical mold 2 is sucked into the mold 3 and integrally held. Thereafter, the upper mold 18 is taken out from the sleeve 15, and the glass 20 that has been molded is taken out from the sleeve 15. At the time of taking out, since the spherical mold 2 is integrated with the receiving mold 3, only the glass 20 can be taken out. The molded functional surface by the spherical shape of the glass 20 taken out is a hemisphere, but in the case of an optical element in which the spherical portion of the optical element is less than the hemisphere, the surface molded by the flat portion 7 of the receiving mold 3 is ground. Then, a meniscus lens having a spherical notch with a desired depth is obtained. According to the present embodiment, since the spherical shape can be integrally held on the receiving die without using a holder or the like, an optical element having a hemispherical optical functional surface without scratching the spherical shape. Can be molded.
(Embodiment 2) Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 3 is a schematic cross-sectional view of a molding apparatus different from the first embodiment when a meniscus lens is molded as a glass optical element. FIG. 4 is an explanatory view of an operation related to the molding apparatus shown in FIG. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. In FIG. 3, a sphere 2 is a sphere 1 whose entire surface is mirror-finished. In the receiving mold 30 for mounting the spherical mold 2, the receiving section 31 for mounting the spherical mold 2 has a concave concave surface and is mirror-finished with the same radius of curvature as the spherical mold 2. The receiving mold 30 is provided with a flange 32 on the outer periphery on the lower side so that the sleeve 15 is placed thereon. The receiving mold 30 is placed on the base plate 33 together with the quartz tube 16 made of transparent quartz glass disposed outside the sleeve 15, and the lower side of the base plate 33 is attached to the lower base 10 via the bellows 34. It is placed on the table 35. In the center of the receiving mold 30, that is, coaxially with the central axis of the receiving mold 30, a suction port 36 that allows the spherical mold 2 to be sucked is formed. The suction port 36 communicates with a pipe 37 welded to a hole drilled in the table 35 through a hole drilled in the base plate 33 and an internal space of the bellows 34. A ring-shaped notch is formed below the suction port 36 of the receiving mold 30 and above the hole of the base plate 33, and a gap between the receiving mold 30 and the base plate 33 is sealed in the notched portion. A ring 60 is inserted. The pipe 37 is provided with an air valve 38 for controlling the intake of air into the bellows 34. The bellows 34 is a stretchable member obtained by folding a SUS plate (stainless steel plate) in a bellows shape, and a hole 39 is formed in a valley portion of the fold so as to communicate the inside and outside of the bellows 34. Further, the O-ring 40 is fitted in the valley portion of the fold, and the hole 39 is opened when the bellows 34 is extended. The upper part of the bellows 34 is hermetically welded to the bottom of the base plate 33, and the lower part of the bellows 34 is hermetically welded to the upper part of the base 35. A case where a meniscus lens is molded by the molding apparatus having the above configuration will be described. Initially, the air valve 38 is closed. First, the upper base 21 is removed, and the spherical mold 2 is placed on the receiving portion 31 of the receiving mold 30 and the sleeve 15 is placed on the flange 32. Then, the glass 20 is placed on the spherical mold 2 and the upper mold 18 is inserted into the sleeve 15 to form a molding assembly 28. Next, the upper base 21 is placed on the reflecting lens barrel 22, and nitrogen gas is introduced from the pipe 26. When the gas enters a state in which the molding die or the like is prevented from being oxidized, heating of the molding assembly 28 is started by the heater 21. When the viscosity of the glass becomes 10 ^13.5 poise or less and fluidity is obtained, the cylinder 25 is operated to pressurize the glass 20. Immediately after starting the pressurization of the glass, the bellows 34 is compressed by the pressing of the cylinder rod 24, and at this time, the air in the bellows 34 is discharged from the hole 39. FIG. 4 is a view showing a state when the bellows 34 is compressed. As the bellows 34 is compressed, the O-ring 40 is crushed and the hole 39 is sealed by the O-ring 40. The pressure applied to the glass 20 by the cylinder 25 becomes a force for compressing the bellows 34 immediately after the start of pressurization and escapes from the glass, but after the compression of the bellows 34 is finished, the pressure applied to the glass increases, and the glass 20 moldings are performed. Next, after raising the cylinder rod 24 and releasing the cylinder rod 24 from the upper mold, heating by the heater 21 is stopped and cooling of the formed glass 20 is started. After the glass 20 is cooled to room temperature, the inflow of the gas is stopped and the upper base 21 is removed from the reflecting lens barrel 22. Next, the upper mold 18 is taken out from the sleeve 15, and after the sleeve 15 is removed from the flange 32 of the receiving mold 30, the glass 20 that has been molded is taken out from the lower mold. At this time, since the inside of the bellows is in a depressurized state more than the outside of the bellows, the spherical mold 2 is sucked to the receiving mold 30 side, and the spherical mold 2 and the receiving mold 30 are integrated, so that the glass 20 Can only be taken out. Next, the air valve 38 is opened, and air flows into the bellows 34 through the pipe 37 and the hole of the base 35 to increase the pressure inside the bellows. By this pressure increase, the bellows 34 can return to the state before molding. The molded functional surface of the glass 20 taken out by the spherical shape is a hemisphere, but if the spherical notch portion of the optical element is less than the hemisphere, the surface formed by the flat surface portion 41 of the receiving die 30 is ground to obtain a desired shape. A meniscus lens having a deep spherical part is formed. According to the present embodiment, the spherical shape and the receiving shape can be integrated without using equipment such as a vacuum pump as in the first embodiment. In addition, since pressure is gradually applied to the glass at the start of pressing the glass, there is also an effect that the glass is not cracked when an optical element having a small thickness is formed. In each of the above embodiments, the spherical shape has been described such that the spherical center is positioned on the central axis of the mold main body. However, the present invention is not limited to this. When placed on the receiving portion formed at the shifted position, a plurality of spherical shapes can be arranged on the molding die main body, and an optical element having a plurality of spherical notches on one surface side of the molded optical element is obtained. be able to. Also in this case, each spherical mold is sucked and held in the mold body through the suction portion. In each of the above embodiments, the spheres constituting the sphere have been described as having a spherical surface. However, the sphere may have a cut surface as long as the gist of the present invention is achieved. For example, when the cut surface is formed at a location corresponding to the suction part or the suction port, or when the spherical shape can be sucked and held in the receiving part even if the cut surface is formed into a spherical surface This does not depart from the gist of the present invention. The present invention also includes the following inventions.
(1) A molding die in which a sphere having a part of a spherical surface as a molding surface is provided as a sphere on the molding die body, and a sphere composed of a sphere whose entire surface is mirror-finished and a part thereof is transferred to an optical element A mold body that has a mirror-finished concave shape having the same curvature as the sphere and has a receiving portion that engages with a part of the sphere, and the mold body separates the molded optical element from the sphere. A molding die having a suction part for sucking and holding a spherical die to a molding die body when molding. According to the molding die having the above configuration, the spherical spherical surface and the receiving portion of the molding die main body are in close contact with each other with the same curvature and mirror surface, so that when the optical element is released from the spherical shape, Adhesive strength with the mold main body acts greatly and scratches are less likely to enter the spherical surface.
(2) In a molding die for molding a lens by pressing glass that has been heat-softened by a pair of molding dies, at least the lower molding die is placed on the molding die body and a part of the spherical surface placed on the molding die body. Is formed of a sphere formed of a sphere that molds the spherical notch portion of the lens, and the surface of the mold body on which the sphere is placed and the entire surface of the sphere are mirror-finished with the same curvature. The side mold has a suction part for sucking and holding the spherical mold in the mold main body when the molded lens is released from the spherical mold. According to the molding die having the above-described configuration, it is not limited to placing the spherical shape on the central axis of the molding die body, and therefore, a plurality of spherical shapes can be placed on the molding die body, A lens having a plurality of spherical notches on the surface can be molded.
[0009]
【The invention's effect】
According to the first and second aspects of the present invention, since a fixing member such as a holder that presses and fixes the spherical shape from the outside of the spherical shape is not used, the spherical shape is not scratched. The mold life can be greatly extended. Further, a hemispherical surface can be used as a molding function surface.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining the concept of an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of a molding apparatus for explaining the first embodiment.
FIG. 3 is a schematic cross-sectional view of a molding apparatus for explaining a second embodiment.
FIG. 4 is an explanatory diagram of an operation related to the molding apparatus according to the second embodiment.
FIG. 5 is an explanatory view of a method for fixing a sphere in a conventional mold.
[Explanation of symbols]
1 true sphere 2 sphere 3 receiving mold (molding die body)
4 Receiving part 5 Suction part 6 Mold 7 Flat part 12 Suction port 13 Suction device 15 Sleeve 16 Quartz tube 18 Upper mold 19 Heater 20 Glass 25 Cylinder 30 Receiving mold 34 Bellows 38 Air valve 40 O-ring

Claims (2)

In a method of fixing a sphere in a molding die in which a sphere whose spherical surface is partly a molding surface is provided on the molding die body, the sphere is sucked when the molded optical element is released from the sphere. A method for fixing a spherical shape in a molding die, characterized in that it is held on the molding die body. A molding die in which a sphere having a part of a spherical surface as a molding surface is provided as a sphere in the molding die main body, the sphere having a sphere having a mirror-finished sphere at least on a surface transferred to an optical element. The molding die body has a concave receiving portion and a suction portion that sucks the spherical shape and holds it in the molding die body when the molded optical element is released from the spherical shape. Mold.

Images