JP2003002671A - Mold for molding glass optical element and method for producing optical element using the mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a press molding for producing a glass optical element in which glass is prevented from entering into a clearance of a mold, and the time and cost for production are suppressed. SOLUTION: The mold comprises an upper mold 10 and a lower mold 15 in which optical surface-molding surfaces 11 and 16 for molding optical surfaces 2 and 3 of a rectangular lens 1 are formed, and an inner body mold 20 in which a side surface-molding surface 21 for molding a side surface 4 of the rectangular lens 1 is formed. In the upper mold 10 and the lower mold 15, continuous surfaces 12 and 17 smoothly continuing from the optical surface-molding surfaces 11 and 16 are formed, and in the inner body mold 20, there are formed opposed surfaces 22 and 27 having reversed shapes of respective continuous surfaces 12 and 17 and opposing the continuous surfaces 12 and 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding die for a glass optical element having an optical surface forming a curved surface and a side surface formed on the edge of the optical surface, and an optical element using this molding die. Manufacturing method.

[0002]

2. Description of the Related Art A lens, which is a type of optical element, has a structure shown in FIG.
Has two optical surfaces 2, 3 and a side surface 4,
There is a strip-shaped lens 1 in which the outer peripheral edges of the optical surfaces 2 and 3 are rectangular.

In the case of forming such a strip-shaped lens 1, in the prior art, as shown in FIG. 9 (a), a cylindrical barrel mold 30a and an upper mold 10a for molding the first optical surface 2,
A mold having a lower mold 15a for molding the second optical surface 3 is prepared, glass for forming the lens 1 is put into the mold, and the glass is heated to a yield point or higher and pressed. Then, as shown in FIG. 2B, the lens 1a to be rotated is molded, and thereafter, as shown in FIG. 1C, unnecessary portions are ground and removed to obtain the strip-shaped lens 1. There is.

In another conventional technique, as shown in FIG. 10 (a), a barrel die 30b having a substantially rectangular through hole formed in the shape of the outer peripheral edge of the strip-shaped lens 1 is provided. A mold having an upper mold 10b for molding the optical surface 2 and a lower mold 15b for molding the second optical surface 3 is prepared, and in the mold,
After the glass forming the lens 1 is put in, the glass 1 is heated to a temperature not lower than the yield point and pressed to obtain the strip-shaped lens 1 as shown in FIG.

[0005]

However, the conventional technique shown in FIG. 9 has a problem that a grinding step for removing unnecessary portions is required, which increases manufacturing time and manufacturing cost.

On the other hand, in the prior art shown in FIG. 10, since the shape of the strip-shaped lens 1 is formed by a mold, the grinding step is unnecessary, and the manufacturing time and the manufacturing cost are shown in FIG. It can be said that it is superior to the conventional technology. However, in this conventional technique as well, as shown in FIG. 11, in order to ensure the sliding of the upper die 10b and the lower die 15b with respect to the body die 30b, the inner peripheral surface 31b of the body die 30b and the outer peripheral surface of the upper die 10b are secured. A relatively large gap C ₀ between the (sliding surface) 13b and the outer peripheral surface (sliding surface) 18b of the lower die 15b, specifically, at least 3 μ.
m or more, and if possible, a gap C _{0 of} 5 μm or more,
There is a problem that the softened glass 8 may enter here and cause so-called biting. Further, in the process of cooling the glass molded by the mold, the gap C ₀ between the molds
There is a problem that the edge portion of the upper die 10b and the edge portion of the lower die 15b may be damaged by the force f that the glass 8 that has entered shrinks.

The present invention focuses on such problems of the prior art, and it is possible to prevent the glass from wrapping around the gap between the molds and to suppress the manufacturing time and the manufacturing cost. It is an object of the present invention to provide a method for manufacturing an optical element using this.

[0008]

[MEANS FOR SOLVING THE PROBLEMS] A molding die for achieving the above object is a molding of a glass optical element having an optical surface forming a curved surface and a side surface formed along an edge of the optical surface. In the mold, an optical surface molding surface for molding the optical surface, and an optical surface molding die having a continuous surface smoothly continuous from the optical surface molding surface, and a side surface molding surface for molding the side surface, And a side surface molding die that has an inverted shape of the continuous surface of the optical surface molding die and that has a facing surface that faces the continuous surface.

Further, in the method of manufacturing a glass optical element for achieving the above object, the molding die is prepared in advance, and the glass for forming the optical element is put into the molding die, Is heated above the sag point, and then the optical surface molding die is pushed toward the side where the glass is present to mold the optical element.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

First, a first embodiment according to the present invention will be described with reference to FIGS. The optical element manufactured in this embodiment is the strip lens 1 described above with reference to FIG.

In this embodiment, as shown in FIG. 1, a rectangular lens 1 is molded using a mold. This mold includes an upper mold (first optical surface molding mold) 10 that molds the first optical surface 2 of the strip-shaped lens 1 and a lower mold (second optical surface mold 3) that molds the second optical surface 3 of the strip-shaped lens 1. A surface molding die 15; an inner body mold 20 for molding the side surface 4 of the strip-shaped lens 1; and a cylindrical outer body die 30 in which these molds are placed. The lower mold 15 is provided with a thermocouple 41 for detecting the temperature of the lower mold 15, and the upper mold 10 is provided with a pressure rod 42 that pushes the thermocouple 41 toward the lower mold 15.
A heater 43 is arranged around the outer body mold 30.

As shown in FIG. 2, the upper die 10 and the lower die 15 are formed in a cylindrical shape so that they can be placed in a cylindrical outer body die 30, and the outer peripheral surface thereof is the inner peripheral surface of the outer body die 30. Sliding surfaces 13 and 18 that can slide against each other are formed. As shown in FIGS. 1 and 3, one end surface of the upper mold 10 and the lower mold 15 is
Optical surface molding surfaces 11 and 16 for molding the optical surfaces 2 and 3 of the rectangular lens 1 are formed, and continuous surfaces 12 and 17 that are smoothly continuous from the optical surface molding surfaces 11 and 16 are formed. . The surfaces on which the optical surface molding surfaces 11 and 16 and the continuous surfaces 12 and 17 are formed are the surface shape of the optical surface molding surface 11a of the upper mold 10a described above with reference to FIG.
It has the same surface shape as the optical surface molding surface of a and is formed in rotational symmetry. Therefore, the optical surface molding surface 1 is formed on one end surface of the upper mold 10 and the lower mold 15 which are formed in rotational symmetry.
The boundaries between the areas 1, 16 and the continuous surfaces 12, 17 are
It is not clear as shown in FIG. 3, but the portion facing the through-hole of the inner barrel die 20 described later has the optical surface molding surface 11,
There are 16 areas, and the inner body die 20 is the upper die 10 and the lower die 1
When the through hole of the inner barrel die 20 is rotated relative to 5, the portions facing the through hole after rotation become the optical surface molding surfaces 11 and 16. In order to obtain the required shape of the optical surfaces 2 and 3, each of the optical surface molding surfaces 11 and 16 is a reverse shape of the optical surfaces 2 and 3 and has a shape that allows for correction due to heat shrinkage. The error is within 500 μm of PV. The contact surface 14 of the pressure rod 42 described above is formed on the other end surface of the upper mold 10, and the hole 19 is formed in the other end surface of the lower mold 15, and the thermocouple 41 described above is provided therein. ing.

As shown in FIG. 4, the inner body die 20 has a cylindrical shape so that it can be inserted into a cylindrical outer body die 30, and its outer peripheral surface slides on the inner peripheral surface of the outer body die 30. A side surface that forms a movable sliding surface 23, and further has a rectangular through hole that matches the shape of the side surface 4 of the strip-shaped lens 1, and the inner peripheral surface forms the side surface 4 of the strip-shaped lens 1. It forms the molding surface 21.

As shown in FIG. 1, a first facing surface 22 facing the continuous surface 12 of the upper mold 10 and having an inverted shape of the continuous surface 12 is formed on one end surface of the inner barrel mold 20, A second facing surface 27 that faces the continuous surface 17 of the lower die 15 and that has an inverted shape of the continuous surface 17 is formed on the other end surface. Since each of the facing surfaces 22 and 27 is an inverted shape of the continuous surfaces 12 and 17 having rotational symmetry, the facing surfaces 22 and 2 are
7 also has rotational symmetry.

The distance between the first facing surface 22 and the second facing surface 27, more precisely, the distance from the end of the side surface molding surface 21 on the side of the first facing surface 22 to the end on the side of the second facing surface 27 is It is basically the same as the width of the side surface 4 of the strip lens 1.

Each mold 10, 15, 2 constituting the above mold
0 and 30 are formed of any one of tungsten alloy, silicon carbide, glassy carbon and the like. It is preferable that the molds are basically made of the same material, but they may be made of different materials. In this case, it is preferable that the materials forming each mold have similar thermal expansion coefficients.

Next, a procedure for manufacturing the strip lens 1 will be described.

First, as shown in FIG. 1 (a), a lower mold 15 and an inner barrel mold 20 are placed in an outer barrel mold 30, and a material for forming the strip-shaped lens 1 is placed in the inner barrel mold 20. The formed glass preform 5 is placed, the upper mold 10 is placed on the glass preform 5, and the heater 43 heats the mold. The glass preform 5 has basically the same volume as the target strip-shaped lens 1, and its outer shape is also close to the shape of the target strip-shaped lens 1.

When it is detected by the signal from the thermocouple 41 that the glass preform 5 is above the glass deformation point by the heating by the heater 43, the upper die 10 is pushed downward by the pressing rod 42, and the glass The preform 5 is deformed. Upper mold 10
When a predetermined amount is pressed, as shown in FIG.
0 and the optical surface molding surfaces 11 and 16 of the lower die 15 and the side surface molding surface 21 of the inner barrel die 20 are in close contact with each other, and the glass preform 5 has a desired shape.

After that, the heater 43 is turned off to start the cooling of the glass. When the glass is cooled to below the glass transition point, the pressure applied by the pressure rod 42 is stopped. When the glass has cooled to room temperature, the upper mold 10 is removed, and the molded glass, that is, the rectangular lens 1 is taken out from the mold.

As described above, in the present embodiment, since the shape of the strip-shaped lens 1 is formed by the mold, the grinding step is unnecessary and the manufacturing time and the manufacturing cost can be suppressed.

By the way, in the mold of this embodiment, as the gap between the mold components, as shown in FIG.
There is a gap C ₁ between the continuous surface 12 and the first facing surface 22 of the inner barrel die 20, and a gap C ₂ between the continuous surface 17 of the lower die 15 and the second facing surface 27 of the inner barrel die 20. . These gaps C ₁ and C ₂ are in the direction in which the continuous surfaces 12 and 17 are widened,
In other words, it spreads in a direction that is smoothly continuous with the optical surface molding surfaces 11 and 16. Therefore, this gap C
As described above with reference to FIG. 11, the glass 9 protruding from ₁ and C ₂ does not wrap around to the side surface of the upper mold 10b or the lower mold 15b, and does not cause so-called biting. Further, the direction of the force f ₁ for shrinking the glass 9 protruding from the gaps C ₁ and C ₂ by cooling is the optical surface molding surfaces 11 and 1.
Since 6 is the direction in which it spreads, upper mold 10 or lower mold 1
Unnecessary force is not applied to 5 and damage to these molds can be prevented.

Further, the gaps C ₁ and C ₂ between the mold components of this embodiment are defined by the side surface of the upper mold 10b and the inner peripheral surface 31b of the body mold 30b in the prior art described with reference to FIG. The clearance C ₀ can be smaller than the clearance C ₀ between the side surface of the lower mold 15b and the inner peripheral surface 31b of the body mold 30b. Specifically, in the prior art, the gap C ₀ needs to be 3 μm or more, whereas in the present embodiment, it can be suppressed to 1 μm or less. This is the gap C _{0 in the} prior art.
In order to secure the sliding of the upper mold 10b and the lower mold 15b with respect to the members forming the above, that is, the upper mold 10b and the lower mold 15b, a certain amount of clearance C ₀ is required between them, but in the present embodiment, The members that form the gaps C ₁ and C ₂ , that is, the upper mold 10 and the lower mold 15 do not slide with respect to the inner barrel mold 20, and the gap for ensuring this sliding becomes unnecessary. This is because the pressurizing direction of the pressurizing rod 42 acts in the direction of narrowing the gaps C ₁ and C ₂ . Therefore, in this embodiment, the thickness of the glass 9 protruding from the gaps C ₁ and C _{2 of the} mold can be reduced.

In this embodiment, the amount of gap of the mold changes depending on the amount of movement of the upper die 10 by the pressure rod 42. Therefore, when it is desired to increase the thickness of the glass 9 protruding from the gaps C ₁ and C _2. For this purpose, the amount of movement of the upper die 10 by the pressure rod 42 may be reduced. That is, in this embodiment, the amount of the gaps C ₁ and C ₂ of the mold can be adjusted by the amount of movement of the upper mold 10 by the pressing rod 42.

Further, in this embodiment, the optical surface molding surfaces 11, 16 and the continuous surfaces 12, 17 of the upper mold 10 and the lower mold 15 are formed.
Since it is formed rotationally symmetrically as in the prior art shown in FIG. 9, a scratch a is formed on a part of the optical surface molding surfaces 11, 16 of the upper mold 10 or the lower mold 15, as shown in FIG. Even if it does, by rotating the inner barrel mold with respect to the upper mold 10 and the lower mold 15 by, for example, 90 °, and making a part of the continuous surfaces 12, 17 into new optical surface molding surfaces (11, 16), This scratch a can be avoided.

In the above embodiment, the inner body mold 20 is used.
All the surfaces of the upper mold 10 and the lower mold 15 facing each other are continuous surfaces 1
2 and 17, the continuous surfaces 12 and 17 can achieve the intended effect if they are formed only in the vicinity of the optical surface molding surfaces 11 and 16. Therefore, the upper mold 10 and the lower mold 10 facing the inner barrel mold 20 are Of the surfaces of the mold 15, only the surfaces around the optical surface molding surfaces 11 and 16 may be the continuous surfaces 12 and 17, and the outer peripheral side may be simply a flat surface, for example. Also in this case, the facing surface of the inner body die 20 naturally has a shape that follows the surface shapes of the upper and lower dies.

Next, a mold as a second embodiment according to the present invention will be described with reference to FIG.

In the mold of this embodiment, a chamfered molding surface 24 for molding a chamfered surface formed at the boundary between the optical surface and the side surface of the strip-shaped lens is formed on the inner barrel mold 20a. The same as in the first embodiment.

The chamfered molding surface 24 is formed at the end of the side surface molding surface 21 of the inner barrel die 20a on the side of the facing surfaces 22 and 27 so as to form an angle of, for example, 45 ° with respect to the side surface molding surface 21. ing.

In this embodiment, since the chamfering molding surface 24 is formed on the inner body die 20a as described above, it is not necessary to chamfer by grinding after press molding, and the manufacturing process can be simplified. In particular, when it is necessary to form the chamfered surface in a three-dimensional undulation, the grinding operation becomes difficult.
It is extremely effective to form the chamfered molding surface 24 on a. In the prior art shown in FIG. 10, the upper die 10b
When it is attempted to form a chamfered molding surface on the lower mold 15b, it becomes extremely difficult to form the end side portions of the optical molding surfaces 11b and 16b forming a curved surface. Therefore, the chamfering is performed by grinding as described above. It is customary.

By the way, the manufacturing method of the rectangular lens and the molding die thereof have been described above.
Needless to say, the present invention can be applied to lenses other than the strip-shaped lens and also to the manufacture of mirrors other than the lens.

[0033]

According to the molding die of the present invention, a gap is formed between the continuous surface of the optical surface molding die and the facing surface of the side surface molding die. Since it spreads in a direction that is smooth and continuous with the optical surface molding surface, the glass protruding from this gap does not go around to the side surface side of the optical surface molding die, and so-called biting does not occur. . Further, since the glass protruding from this gap shrinks due to cooling in the direction in which the optical surface molding surface is widened, unnecessary force is not applied to the optical surface molding die, and damage to the mold can be prevented.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a manufacturing procedure of a strip lens in a first embodiment according to the present invention.

FIG. 2 is a plan view of a mold according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a region of an optical surface molding surface and a region of a continuous surface of an upper mold and a lower mold in the first embodiment according to the present invention.

FIG. 4 is a plan view of an inner barrel die according to the first embodiment of the present invention.

FIG. 5 is an explanatory view showing a gap of a molding die and a glass entering the gap in the first embodiment according to the present invention.

FIG. 6 is an explanatory diagram showing a coping method when a scratch is formed on the optical surface molding surface in the first embodiment according to the present invention.

FIG. 7 is a sectional view of a molding die according to a second embodiment of the present invention.

8A and 8B are views showing the shape of a strip lens, FIG. 8A is a plan view, FIG. 8B is an AA sectional view, and FIG. 8C is a BB sectional view.

FIG. 9 is an explanatory diagram showing a manufacturing procedure of a conventional rectangular lens.

FIG. 10 is an explanatory view showing another manufacturing procedure of the conventional strip lens.

FIG. 11 is an explanatory diagram showing a state inside the mold in the manufacturing procedure shown in FIG.

[Explanation of symbols]

1 ... strip-shaped lens, 2 ... first optical surface, 3 ... second optical surface,
4 ... Side surface, 10 ... Upper mold (optical surface molding mold), 11, 16 ...
Optical surface molding surface, 12, 17 ... Continuous surface, 13, 18 ... Sliding surface (side surface), 15 ... Lower mold (optical surface molding mold), 20, 20
a ... Inner body mold (side mold), 21 ... Side mold surface, 2
2, 27 ... Opposing surface, 23 ... Sliding surface, 24 ... Chamfering molding surface, 30 ... Outer barrel mold, 41 ... Thermocouple, 42 ... Pressurizing rod, 4
3 ... heater.

Claims (5)

[Claims] 1. A molding die for a glass optical element having a curved optical surface and a side surface formed along an edge of the optical surface, comprising: an optical surface molding surface for molding the optical surface; An optical surface molding die having a continuous surface smoothly continuous from the optical surface molding surface, a side surface molding surface for molding the side surface, and an inverted shape of the continuous surface of the optical surface molding die. A side surface molding die having a facing surface facing the continuous surface, and a molding die for a glass optical element. 2. A molding die for a glass optical element having, as optical surfaces, a first optical surface and a second optical surface forming a curved surface, and a side surface formed along an edge of each optical surface. An optical surface molding die that molds each optical surface of the optical element, a first optical surface molding surface that molds the first optical surface, and a first continuous surface that is smoothly continuous from the first optical surface molding surface. A first optical surface molding die having a surface, a second optical surface molding surface for molding the second optical surface, and a second continuous surface that is smoothly continuous from the second optical surface molding surface. And a second side surface forming surface for forming the side surface, and an inversion shape of the first continuous surface of the first side surface forming mold. A first facing surface facing the surface and an inverted shape of the second continuous surface of the second optical surface molding die. Molding die glass optical element characterized in that it comprises a, and a side mold having a second surface facing the said second continuous surface. 3. The molding die for a glass optical element according to claim 2, wherein the first continuous surface of the first optical surface molding die and the first facing surface of the side surface molding die face each other, Also, two optical surface molding dies and a tubular cylinder into which the side molding dies are inserted in a state where the second continuous surface of the second optical surface molding die and the second facing surface of the side surface molding die face each other. A mold, wherein at least one of the two optical surface molding dies in the barrel mold has a cylindrical inner peripheral surface in a perspective direction with respect to the other optical surface molding dies. A molding die for a glass optical element, characterized in that a slidable sliding surface is formed. 4. The molding die for a glass optical element according to claim 1, wherein the side surface molding die is a surface forming a predetermined angle with respect to the side surface molding surface. And a chamfered molding surface for molding a chamfered surface formed at a boundary between the optical surface of the optical element and the side surface is formed at an end of the side surface molding surface on the opposite surface side. Mold for glass optical element. 5. A glass molding die for a glass optical element according to claim 1, wherein glass for forming the optical element is placed in the molding die, The method for producing an optical element, comprising: heating the glass to a temperature not lower than the sag point, and then pressing the optical surface molding die toward the side where the glass is present to mold the optical element.