JPS61242921A - Molding device for glass lens - Google Patents

Abstract

PURPOSE:The titled device providing high precision lens face, capable of eliminating centering operation, wherein sliding core parts which can be brought into contact with the sides of a glass lens mold and separated from it are set and a dent is made at the outer peripheral part of lens pressing face of the mold. CONSTITUTION:In a state where the sliding core parts 3 and 4 are moved backward to a given position in the arrow X direction and the upper mold 2 is raised to a given position in the arrow Z direction, the glass lens material heated to a softening temperature is placed on the mold face 1a of the lower mold 1. The sliding core parts 3 and 4 are advanced and normally brought into contact with the sides of the column of the lower mold 1. Then, the upper mold is lowered until the flange part of the upper mold 2 is brought into contact with the top faces of the sliding core parts 3 and 4. The lens material is made to flow along the shapes of the mold faces 1a and 2a by the pressing force of the upper mold 2, a lens effective diameter part is formed and the excess part is made to flow into the dent 8. Consequently, the glass lens 9 having a desired lens face shape and a lens outer diameter is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a glass lens molding apparatus for molding glass lenses, such as camera lenses, used in optical equipment.

Conventional technology Conventionally, as a glass lens molding device, for example,
As proposed in Japanese Patent No. 38126, a method is used in which a glass lens material heated to a predetermined temperature is press-molded using a pair of molds.

Problems to be Solved by the Invention However, in the case of such a conventional device, the axes of the molds constituting the lens surfaces must be aligned with each other with high precision, and each lens surface must be aligned so that the optical axis is not tilted. Each mold must be assembled and configured with precision so that they match. Furthermore, unless the volume of the supplied glass lens material is stabilized with high precision, the lens thickness or lens surface shape cannot be accurately obtained, and predetermined optical performance such as focal length cannot be obtained. Furthermore, if the volume of the glass lens material to be supplied is larger than the volume required for the molded lens, even if the desired lens thickness and lens surface shape are obtained, the excess lens material will protrude toward the outer circumference of the mold, and after the lens is molded. , a centering process is required to make the outer diameter of the lens constant. Centering work requires a large number of man-hours, increases costs, and is undesirable because there is a high risk of damaging the lens surface during the work process.

In addition, as a means to solve these problems,
The devices disclosed in Japanese Patent Application Laid-open No. 141335 and Japanese Patent Application Laid-Open No. 59-203732 have been proposed, but they have the following problems. That is, a common problem is that the remaining portion of the glass protrudes toward the outer periphery of the molded lens, increasing the maximum diameter of the lens and requiring removal of the remaining portion. In JP-A-59-141335,
When the molded lens is removed from the mold after molding is completed, it is difficult to release the molded lens from the mold because the molded lens is pressed in the diametrical direction and lens surface direction of the lower mold and is in close contact with the lower mold.

Furthermore, in JP-A-59-203732, the thickness of the molded lens is affected by the thermal expansion of the mold or the deflection or deformation of the member holding the mold, resulting in variations.

The present invention solves the above-mentioned conventional problems, and allows variation in the volume of supplied lens material within a wide range, eliminates the need for centering work after lens molding, and achieves desired lens shape accuracy and lens optical axis. In addition, the outer diameter of the lens is the same or slightly larger than that of conventional polishing methods, and the reference surface is the outer diameter of the lens and the lens surface to make it easier to accurately hold the lens when assembled into the lens barrel. It is an object of the present invention to provide a glass lens molding device which satisfies the requirements for downsizing and weight reduction of the lens barrel.

Means for Solving the Problems In order to solve the above problems, the glass lens molding apparatus of the present invention includes a mold for press-molding a glass lens material heated to a predetermined temperature, and a mold that abuts and separates from the side surface of the mold. It has a structure including a slide core part that can move forward and backward, and a recessed part formed on the outer periphery of the lens pressing surface of the mold.

Effect: According to the above configuration, by press-molding a glass lens material with a volume slightly larger than the target lens shape volume, the excess glass escapes into the recess, a highly accurate lens surface is obtained, and centering work is not required. Can be done. Moreover, the eccentricity and inclination of the mold, and the lens thickness dimension can be controlled by the slide core portion.

Embodiments Hereinafter, embodiments of the present invention will be explained based on FIGS. 1 to 4.

FIG. 1 is a schematic sectional view of a glass lens molding apparatus according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1, where 1 is a lower mold, 2 is an upper mold, 1a, 2a is a mold surface 3.4, slide core parts 5 to 7 are cylinder devices, 8 is a recess formed at appropriate intervals in the circumferential direction on the outer periphery of the mold surface 2a, and 9 is a molded glass lens. Said lower mold 1
The upper mold 2 is made of a predetermined ceramic material or the like at one end.
The mold surface is formed into a cylindrical shape with a flange, and is arranged with the same axis, and the other end surface of each mold is perpendicular to the mold axis and forms a predetermined molded lens surface shape with high precision. 1a, 2a, these mold surfaces 1a, 2
A is finished to a predetermined mirror surface. In this example, in order to obtain a convex lens, the mold surface shape was respectively concave. The lower mold 1 is in a fixed state, and the upper mold 2 is driven by a predetermined driving source, such as an air or hydraulic cylinder device 5.
, that is, the optical axis direction of the molded glass lens 9 (direction of arrow (Z) in FIG. 1) by a predetermined stroke amount at a predetermined speed. In addition, the upper mold 2 and the lower mold 1 have a heater, such as a cartridge heater, etc., for heating the glass lens material supplied to the mold surface to a predetermined temperature, and a thermal lightning pair for detecting temperature buried in a predetermined position. (not shown).

Further, the outer diameter dimensions of the cylindrical portions of the upper mold 2 and the lower mold 1 are configured to be larger than the effective diameter dimension of the molded glass lens 9 by a predetermined amount, and the mold surface 2a of the upper mold 2 has a portion outward from the effective diameter portion. Three recesses 8 are formed at a predetermined depth at approximately equal angular positions on the lens pressing surface of the outer edge. When the upper mold 2 and the lower mold 1 press-mold the glass lens material into the desired lens shape, the slide core parts 3 and 4 are placed in advance so that they come into contact with the cylindrical side surfaces of both the upper mold 2 and the lower mold 1. As shown by the phantom lines in Fig. 2, two-part slide core parts 3 and 4 made of ceramic members or the like surround and hold the cylindrical side surfaces of the upper mold 2 and the lower mold 1. The cylinder device 6.7 is configured to move forward and backward in the arrow (X) direction, respectively. A cartridge heater and a thermocouple for keeping the glass lens material at a predetermined temperature are also embedded in the slide core portion 3.4 at predetermined positions (not shown). When the slide core portion 3.4 is in proper contact with the upper mold 2 and the lower mold 1, a space is formed that has the same lens surface shape, lens thickness, and outer diameter as the target lens.

Three recesses 8 of a predetermined depth are formed on the mold surface 2a of the upper mold 2 at positions corresponding to the outer edge of the molded glass lens 9. The volume of the recess 8 is formed to a predetermined size in consideration of the range of variation in the glass lens material supplied to the mold. Therefore, the volume of the glass lens material supplied to the mold surface 1a of the lower mold 1 is, as a matter of course,
The amount is smaller by a predetermined amount than the sum of the lens volume and the volumes of the three recesses. That is, when the upper mold 2 reaches the bottom dead center position, the mold surface 2a and the mold surface 1a of the lower mold 1 move forward and the slide core portion 3.
4 is limited to a range that does not exceed the volume of the space surrounded by 4. Note that the glass lens material may be supplied in any desired shape, such as a ball, rectangular parallelepiped, or disk shape.

Next, a process of molding a desired molded glass lens 7 using the glass lens molding mount having the above structure will be described.

First, the slide core portion 3.4 has retreated to a predetermined position in the arrow (X) direction, and the upper die 2 has also risen to a predetermined position in the arrow (Z) direction. In this state, a predetermined amount of spherical or rectangular glass lens material heated to a predetermined softening temperature is supplied onto the mold surface 1a of the lower mold 1 and mounted thereon. After that, move the slide core part 3.4 forward,
It is brought into regular contact with the cylindrical side surface of the lower mold 1. Next, the upper mold 2 is driven and lowered until the 7 flange portions of the upper mold 2 come into contact with the upper end surface of the slide core portion 3.4, thereby press-molding the glass lens material and forming a predetermined convex molded glass. Lens 9 is molded. Specifically, the glass lens material is heated by a pair of upper and lower molds 1 through a preheating process,
Since the glass lens material is pressed while maintaining its softened state, the pressing force of the upper mold 2 causes the glass lens material to flow along the shape of the mold surfaces 1a2a of the upper mold 2 and the lower mold 1, and first, as shown in FIG.
The effective diameter portion of the lens is formed as shown by the imaginary line, and the liquid also flows to the outer peripheral portion of the lens outward from the effective diameter portion of the lens, thereby filling the recess 8 . As a result, the desired lens surface shape and lens outer diameter are formed. The measurement variation of the glass lens material to be supplied is caused by the outer edge of the lens and the mold surface 1 of the upper mold 1.
Since it is absorbed as a variation in the amount of glass flowing into the three concave portions 8 provided on the a side, the accuracy of the lens surface shape of each lens effective diameter part and the dimensional accuracy of the lens outer diameter and lens thickness are affected by the measurement variation. It is always molded into a constant shape with high precision without being subjected to any damage. Furthermore, regarding the lens reference planes necessary to accurately configure the lens spacing and lens optical axis when incorporating into vAWA, the outer periphery of the molded glass lens 7 is provided with (R), (AR), (AL). In addition, (R) is the lens outer diameter reference plane, (AR) (A
L) is a reference plane on the lens surface side. 3(A) is a front view of the molded glass lens 9, and FIG. 3(B) is a sectional view taken along the line ■-■ in FIG. 3(A). Thereafter, after passing through the steps of cooling and solidifying the molded glass lens 9, the upper die 2 is raised and the slide core portion 3.4 is retracted, thereby completing the convex lens shown in FIG. 3. here,
The relationship among the preheating temperature of the glass lens material, the heating temperature and heating time of the upper and lower molds 1 and 2, the pressing force of the upper mold 2, the bottom dead center position of the upper mold 2, the volume of the recess 6, etc. is important, and the relationship is important. Predetermined conditions must be set depending on the shape and dimensions of the lens, the type of glass material used, etc.

FIG. 4 is a schematic cross-sectional view of a glass lens molding apparatus according to another embodiment of the present invention, which differs from the first embodiment in that the slide core portions 11 and 12 contact only the cylindrical side surface of the upper mold 2. It is. In this case as well, it is possible to obtain the effects of highly accurate lens surface shape accuracy, lens outer diameter dimensions, etc., and the effect of eliminating the need for centering processing after lens molding, as in the case of the first embodiment. .

In each of the above embodiments, the position, shape, and dimensions of the recesses 8 provided on the mold surface 2a of the upper mold 2 may be set arbitrarily; for example, instead of three recesses 8, an annular recess may be used. However, it may also be formed on the lower mold 1 as well.

Also, the upper mold 2 and the slide core part 3.4 or 11, 1
The means for driving 2 is not limited to a cylinder device,
Of course, any means such as a cam may be used.

Moreover, it is not necessarily necessary to fix the lower mold 1 of the pair of molds 1.2, and both may be driven.

Effects of the Invention As described above, according to the present invention, a glass lens material that is slightly smaller than the sum of the lens volume and the volume of the concave portion is pressurized and molded, and the measurement variation of the glass lens material is reduced to the outer periphery of the lens surface of the mold. Since it can be absorbed as a variation in the amount of glass flowing into the recess provided in the mold, it is possible to form the lens surface shape and the lens outer diameter with high accuracy, and there is no need for centering after molding. Furthermore, the slide core that comes into contact with the cylindrical side of the mold allows the axes of the mold to be aligned with precision and to keep the lens surface from tilting, and the slide core also regulates the downward position of the mold. However, the lens thickness dimension can be made constant, and a molded glass lens with extremely high precision can be realized. Furthermore, the outer diameter of the lens can be made almost the same as that of conventionally ground lenses, and a flat reference surface can also be formed on the lens surface side, so the lens holding barrel can be made smaller and smaller.
It is possible to achieve weight reduction and ease of assembly.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view of a glass lens forming apparatus according to an embodiment of the present invention, Fig. 2 is a sectional view taken along line II-II in Fig. 1, and Fig. 3 (A) is a schematic sectional view of a glass lens forming apparatus according to an embodiment of the present invention. A plan view of a molded glass lens, FIG. 4 (B) is a sectional view taken along the line I-1 in FIG. It is. 1...Lower mold, 2...Upper mold, 1a, 2a...Mold surface, 3, 4.11.12...Slide core part, 8...
・Concave Agent Yoshihiro Morimoto Figure 4 Figure 8 (A) (B)N
'b

Claims (1)

[Scope of Claims] 1. A mold for press-molding a glass lens material heated to a predetermined temperature, and a mold that moves forward and can come into contact with and separate from the sides of the mold.
A glass lens molding device comprising a slide core part that retreats and a recessed part formed in the outer peripheral part of the lens pressing surface of the mold. 2. The glass lens molding apparatus according to claim 1, wherein the molding die includes an upper mold and a lower mold, and the recess is formed in the upper mold. 3. The glass lens molding apparatus according to claim 1, wherein the molding die includes an upper mold and a lower mold, and the recess is formed in the lower mold. 4. The glass lens molding apparatus according to claim 1, wherein the molding die includes an upper mold and a lower mold, and the recessed portion is formed in both the upper mold and the lower mold. 5. The glass lens molding device according to any one of claims 1 to 4, wherein the concave portion is formed in an annular shape over the entire length of the outer peripheral portion of the lens pressing surface of the mold. 6. The glass lens molding apparatus according to any one of claims 1 to 4, wherein a plurality of recesses are formed at predetermined intervals on the outer periphery of the lens pressing surface of the mold.