JP3252175B2 - Manufacturing method of glass lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a glass lens by press molding under heating using first and second molds.

[0002]

2. Description of the Related Art Conventionally, a glass lens has been manufactured through a polishing step of giving a design curvature to a lens surface and a centering step of aligning an optical axis by grinding. However, in recent years, relatively small-diameter glass lenses, mainly aspherical lenses, have been directly manufactured by press molding using a mold (Japanese Patent Publication No. 3-52417).

[0003] In the conventional molding of a glass lens, the mold must be separated from the transfer surface of the mold when the mold is cooled after molding. Material was selected. For convex lens molding: α ₁ = α ₂ <α _{0 For} concave lens molding: α ₁ = α ₂ > α ₀ (α ₁ : thermal expansion coefficient of lower mold α ₂ : thermal expansion coefficient of upper mold α ₀ : 100 to Thermal expansion coefficient of molding glass material between 300 ° C)

[0004]

However, in a glass forming system having an automatic transfer function in which an upper mold and a lower mold are used and a molded lens is taken out of the mold by a robot and is conveyed, a molded lens and a mold are simply used. It is not sufficient that the lens is separated from the lens, and it is necessary to selectively leave the molded lens only on one of the upper mold and the lower mold.

When the above-mentioned conventional upper and lower dies are used, it is conditionally the same as to whether the molded lens remains on the upper or lower die when the mold is opened up and down. Yes,
It turned out to be unfavorable in terms of automation. The present invention
It is an object of the present invention to surely leave a molded lens in one of a lower mold and an upper mold in hot press molding of a glass lens.

[0006]

According to the present invention, there is provided a method of manufacturing a glass lens, comprising pressing a glass material for molding between a first mold and a second mold under heating to form the glass lens, and cooling the glass lens. In a method of manufacturing a glass lens in which the first and second molds are later opened to collect the molded lens, the first mold has a thermal expansion coefficient of α ₁ , the second mold has a thermal expansion coefficient of α ₂ , and the first mold has a thermal expansion coefficient of α ₂ . And the second
When the coefficient of thermal expansion of the molding glass material at the opening temperature of the mold is α ₀ , (a) when the transfer surface of the first mold forms a convex surface on the molded lens, α ₁ <α ₀ ; And (α ₀ −α ₂ ) <
(Α ₀ -α ₁₎ satisfied, whereas (b), the transfer surface of the first mold, when the concave is formed in the molded lens, alpha _1> alpha ₀ and,, (alpha ₁ -
α ₀ )> (α ₂ −α ₀ ) .
When the first mold and the second mold are opened, the first mold and the molding
Lens is selectively released, and the molded lens is placed on the second mold.
Selectively adhere and leave, then mold from second mold
The method is characterized in that the lens is collected . This allows molding
When opening the mold after, securely on the second form, the molded lens is rest, this is reliably collected by a robot
be able to.

[0007]

FIG. 1 is an exploded sectional view at the time of molding showing the relationship between an upper mold, a lower mold and a molded lens according to the present invention. FIG.
FIG. 3 is an explanatory view showing each step in the manufacturing method of the present invention. In this embodiment, the upper die 11 is a first die and the lower die is a second die.

The upper mold 11 and the lower mold 13 are each made of heat-resistant ceramics, super-hard materials, metals, and the like. In FIG. 1, the transfer surface 11a of the upper mold 11 is concave, and as a result, a convex surface is formed on the molded lens 21.
On the other hand, when the transfer surface 11a of the upper mold 11 is convex, the molded lens 21 has a concave surface. In the present invention, the molding lens 21 is
The material of the upper mold 11 and the lower mold 13 is selected according to whether a convex surface is formed or a concave surface is formed.

(1) By the transfer surface 11a of the upper mold 11,
Α ₁ <α ₀ and (α ₀ −α ₂ ) <(α ₀ −α ₁ ) (α ₁ : coefficient of thermal expansion of upper mold α ₂ : heat of lower mold) Expansion coefficient α ₀ : coefficient of thermal expansion of the glass material for molding at the opening temperature of the upper mold and the lower mold.
When a convex surface is formed, it is preferable that α ₁ <α ₂ <α ₀ . On the other hand, when a concave surface is formed on the molded lens 21 by the transfer surface 13a of the lower mold 13, α ₁ <α ₀ <α ₂
It is preferable that Thus, the sign of α ₀ −α ₂ is
It depends on the surface shape of the lens formed by the transfer surface 13a of the lower mold 13.

(2) By the transfer surface 11a of the upper mold 11,
Α ₁ > α ₀ and (α ₁ −α ₀ )> (α ₂ −α ₀ ) Here, when the concave surface is formed on the molded lens 21, the molded lens 21 is formed by the transfer surface 13 a of the lower mold 13.
When a concave surface is formed, it is preferable that α ₁ > α ₂ > α ₀ . On the other hand, when a convex surface is formed on the molded lens 21 by the transfer surface 13a of the lower mold 13, α ₁ > α ₀ > α ₂
It is preferable that

[0011] In general, since by opening the upper die 11 and lower die 13 when cooled to 100 to 300 ° C. after molding removing the molded lens 21, as alpha ₀ is 100-30
The coefficient of thermal expansion of the molding glass material at 0 ° C. may be considered.

An example of a specific combination of a glass material and a mold is as follows. (1) on-type for the double-convex lens _{11: SiC (α 1 = 43} × 10 -7) the lower die 13: carbide ^{_{(α 2 = 60 × 10 -7}} ) glass _{material: SF6 (α 0 = 85 ×} 10 - ⁷ )

(2) In the case of a biconcave lens Upper mold 11: heat-resistant stainless steel (α ₁ = 113 × 10 ⁻⁷ ) Lower mold 13: alumina (α ₂ = 78 × 10 ⁻⁷ ) Glass material: SK5 (α ₀ = 75 × 10 ^-7 )

The process of forming a glass lens will be described below with reference to FIG. (1) First step: FIG. 2 (A) A glass material 23 made of preformed optical glass is sucked and held by a suction pad 33 attached to an arm 31 of the robot, and set on the lower mold 13. I do.

(2) Second step: FIG. 2B A lens 21 (a biconvex lens) is pressed between the upper mold 11 and the lower mold 13 by heating.

(3) Third step: FIG. 2 (C) When the temperature of the molded lens 21 decreases to 100 to 300 ° C., the upper mold 11 is pulled up.

At this time, the magnitude relationship between the thermal expansion coefficients of the upper and lower dies 11 and 13 and the molded lens 21 (glass material) is such that the upper die 11 <the lower die 13 <the molded lens 21. The difference in the coefficient of thermal expansion from mold 11 is lower mold 1
3 and the molded lens 21, the upper mold 11 and the molded lens 21 are detached first due to shrinkage during cooling after molding, and the molded lens 21 remains on the lower mold 13 without fail. . Therefore, it can be picked up from above the lower mold 13 by the robot in the next step.

(4) Fourth step: FIG. 2 (D) The suction pad 33 is lightly pressed against the formed molded lens 21 at 100 to 300 ° C., and the inside of the suction pad 33 is suctioned with a negative pressure. Then, the lens 21 is pulled up by the suction pad 33. At this time, since the thermal expansion coefficient of the lower mold 13 is larger than that of the molded lens 21, the lower mold 13
The lens and the lens 21 are smoothly detached from each other, and it is possible to prevent the suction pad 33 from being hindered from being pulled up.

(5) Fifth Step The molded lens 21 is transferred to a pallet and aligned in the pallet. In the above, the molding of the lens having the convex surface on the upper mold 11 side has been described, but the same applies to the case where the lens is concave.

In the above embodiment, the upper die 11 is the first die and the lower die 13 is the second die.
If the mold 1 is the second mold and the lower mold 13 is the first mold and the above-mentioned relationship of the coefficient of thermal expansion is satisfied, the molding lens 21 can be securely left on the upper mold 11 for molding.

[0021]

According to the present invention, the first and second mold materials are selected according to the glass material of the lens in consideration of the relationship between the coefficients of thermal expansion determined by the shape of the lens, so that the first and second molds can be reliably formed. The molded lens is left on the mold 2 and molded, and the lens can be picked up and transported by a robot.

[Brief description of the drawings]

FIG. 1 is an exploded sectional view showing the relationship between a mold and a molded lens during molding.

FIG. 2 is an explanatory view showing each step of lens molding.

[Explanation of symbols]

 11 Upper mold 11a Transfer surface 13 Lower mold 13a Transfer surface 21 Molded lens 23 Glass material 31 Arm 33 Suction pad

Claims (1)

(57) [Claims] 1. A glass lens is formed by pressing a glass material for molding between a first mold and a second mold while heating, and after cooling, the first mold and the second mold are opened. A method of manufacturing a glass lens for recovering a molded lens, comprising: a first mold having a thermal expansion coefficient of α ₁ , a second mold having a thermal expansion coefficient of α ₂ , and a molding glass at an opening temperature of the first and second molds. When the thermal expansion coefficient of the material is α ₀ , (a) When a convex surface is formed on the molded lens by the transfer surface of the first mold, α ₁ <α ₀ and (α ₀ −α ₂ ) <
(Α ₀ -α ₁₎ satisfied, whereas (b), the transfer surface of the first mold, when the concave is formed in the molded lens, alpha _1> alpha ₀ and,, (alpha _{1-.alpha. 0} )> (Α ₂ −α ₀ ) and the first mold and the second mold were opened.
The mold and the molded lens are selectively separated
Selectively attaching and leaving the shaped lens on the second mold;
And recovering the molded lens from the second mold .