JP2000281364A - Press die for forming optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the pressure in a glass substrate uniform and improve formability of the glass substrate and transferability of the form of a die. SOLUTION: The press die is used for forming an optical element such as V-groove base plate for arranging optical fibers. Glass 15 to be formed having a coefficient of thermal expansion lower than that of the material of the die is used. Projections 14 are provided at both sides of each forming part on the press surface 11 of the die so that each projection 14 is stuck into the glass 15 to be formed at the time of forming, thereby flowing out of the glass 15 to be formed to outside is inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press die for molding an optical element, which can be suitably used for press molding a press molding material such as low expansion glass.

[0002]

2. Description of the Related Art Hitherto, optical components such as an optical fiber array, a lenticular lens, and a prism array substrate have been known as optical elements. These optical components are composed of a glass substrate having irregularities, grooves, and the like on the surface, and these molded products are generally molded using a press die composed of an upper die and a lower die.

[0003] That is, a glass substrate is produced by pouring a molten glass material into a mold and press-molding the glass substrate.
By a two-stage molding of a first molding step of molding the molten glass into a plate-like glass substrate and a second molding step of reheating the glass substrate obtained in the first molding step to more precisely mold the glass substrate,
We are making glass substrates.

Here, in the case of forming a glass substrate having irregularities and grooves on the surface as described above, a second forming step,
In the so-called reheat press step, molding is performed using a press die composed of an upper die and a lower die having a concave / convex shape, a groove-shaped molding surface in any one of these upper die and lower die. When the glass material to be press-molded has a lower expansion than the mold material, for example, when the material has a small dimensional change with respect to heat, such as low expansion glass, the structure is such that the pressing pressure is uniformly transmitted to the material. In the fitting type (bowl type), after the press molding, the mold material shrinks during cooling, which causes an overtightened state on the side surface of the mold. For this reason, in the case of a low expansion material, the side surfaces of the mold must be opened and press-formed, and as a result, the molding pressure is not uniformly transmitted to the molded member, and the transferability of the mold shape is reduced. (The dimensional accuracy of the entire substrate cannot be ensured).

FIG. 2 is a cross-sectional explanatory view showing an example of a conventional multi-batch molding die for a fiber array and a multi-cavity molding formed by the die. A conventional multi-piece molding die (upper die) 1 for a fiber array has a V-convex array group 4 in which a plurality of V-convex portions 3 as molding portions are provided on a press surface 2 thereof. When the upper mold 1 and the lower mold (not shown) press-mold a glass material from above and below, a multi-cavity molded product 5 is formed. In this press molding, as shown in the pressure distribution image shown in FIG. 2, the glass material flows out at the time of press molding, and the press pressure decreases toward the end of the obtained molded product 5, and the shape of the mold is transferred. The V groove 6 that cannot be formed is formed, and only the V groove 7 at the center can transfer the mold shape. As described above, when a large number of fiber arrays are taken from a large molded product, the pressure distribution becomes remarkable, causing sagging of the shape at the element portion, and the accuracy cannot be ensured.

[0006]

The multi-cavity molding 5 of the fiber array shown in FIG.
The portions to be used as the fiber array substrate are the V-groove portion 7 in which several V-grooves are arranged in rows and the flat portions 8 on both sides thereof. A part of the flat portion 8 between the V-groove portion 7 and the adjacent V-groove portion 7 of the multi-cavity molded product 5 is cut into pieces by cutting with a slicer or the like to obtain individual fiber array substrates. Therefore, the cutting margin 9 is unnecessary for the fiber array. Therefore, in the present invention, by providing a wall for preventing the outflow of the glass material in the portion 9 of the cutting margin, the pressure uniformity in the glass substrate is improved, so that the moldability of the glass substrate, that is, the mold shape It is an object of the present invention to improve the transferability of the ink.

[0007]

Means for Solving the Problems According to the present invention, there is provided a press die for molding an optical element,
The molding glass is relatively low-expansion glass with respect to the mold material, and has projections on both sides of the molding portion on the pressing surface of the mold. The present invention provides a press die for molding an optical element, which prevents the glass for use from flowing out.
In the press die of the present invention, it is preferable to provide projections having a V-shaped cross section on both sides of the molded portion.
In the present invention, the press die may be composed of an upper die and a lower die, and the protrusion may be present on one of the upper die and the lower die. Also,
In the present invention, the protrusions can be provided only on the outermost side portions of the press surface forming portion of the mold, and this configuration is sufficiently effective. In the press mold of the present invention, it is possible to provide a projection in a direction orthogonal to a projection provided on a mold having a molding portion on a flat mold having no molding portion, that is, a molding portion, that is,
In order to equalize the pressure in the direction parallel to the V-groove of the V-shaped portion,
preferable. In the present invention, the optical element to be molded is specifically a V-groove substrate for aligning optical fibers. Low expansion glass has a coefficient of thermal expansion of 5
It is preferably at most 0 × 10 ⁻⁷ / K.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A press mold for molding an optical element of the present invention uses glass whose molding glass has a relatively low expansion relative to a mold material, and is provided on both sides of a molding portion on a press surface of the mold. With the structure having the projections, the projections pierce the molding glass during molding, thereby preventing the molding glass from flowing out. Thus, at the time of press molding,
Since the molding glass was prevented from flowing out of the mold,
The molding pressure is uniformly applied to the entire surface of the glass substrate, and the moldability of the glass substrate (the mold shape transferability) is improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to these embodiments. FIG. 1 is an explanatory cross-sectional view showing one embodiment of a press die (a multi-piece molding die for a fiber array) and a multi-piece molding according to the present invention. In FIG. 1, reference numeral 10 denotes a molding die (upper die) for molding a large number of fiber arrays.
A V-shaped row group 13 provided with a large number of convex-shaped portions 12 is provided, and projections 14 are provided on both sides of the V-shaped convex portion 12. In addition,
The protrusion 14 is provided on a cutting margin 16 which is not necessary for a fiber array. When the upper mold 10 is configured as described above, when the upper mold 10 and the lower mold (not shown) press-mold a glass material from above and below, the projections 14 pierce the molding glass 15 and the molding glass 15 The multi-cavity molded product 15 is formed in a state where the outflow to the outside is prevented.

In this press forming, as shown in a pressure distribution image shown in FIG.
Does not flow laterally, so that the pressing pressure in each V-convex portion 12 is made uniform, and the transferability of the V-convex portion 12 as a molding portion is improved. Since the pressure of the projections 14 has a large distribution, distortion and non-uniformity of the molding glass 15 are also supposed. However, since the portions where the projections 14 pierce are cut margins, there is no problem because they are removed by cutting. The shape of the projection 14 is V-shaped in FIG. 1, but is not limited thereto, and may be a conical shape, a pyramid shape, or a continuous dot shape thereof. It is preferable that the shape of the projection 14 has a good mold releasability and is easy to pierce the molding glass. In addition, the protrusions 14 do not necessarily need to be on both sides of all the V-shaped portions 12, and may be provided only on the outermost side portions of the V-shaped row group 13 including a large number of V-shaped portions 12. This configuration is sufficiently effective.

Next, another embodiment of the press die according to the present invention will be described. Since the glass substrate as the press molding material is a flat plate, the outflow of the molding glass occurs in a two-dimensional direction. For this reason, the above-mentioned protrusions are
By setting the groove in a direction perpendicular to the groove, the flow of the forming glass in the two-dimensional direction can be reduced and the forming pressure can be made uniform. As a result, the formability of the glass substrate can be improved. However, it is impossible to form a projection orthogonal to the V-groove of the V-convex portion on the press surface of the press die by a high-precision grinding process because of its structure, and it is necessary to form the projection by electric discharge machining or the like. . However, in electric discharge machining, a dimensional variation of about 10 μm occurs in the groove accuracy, and it cannot be practically used as a V-groove for a normal single mode fiber.

For this reason, the V-groove of the V-shaped convex portion of the die is subjected to die processing by grinding, and only the die portion corresponding to the surface portion to be the upper surface of the molded product is subjected to electric discharge to be orthogonal to the V-groove. Forming projections. This makes it possible to prevent the outflow of the forming glass in a direction parallel to the V-groove to some extent, and to achieve uniform forming. But,
According to EDM, the surface is rough and the dimensional accuracy is 10
At about μm, undulation also occurs. Therefore, the state of the upper surface of a product such as a fiber array is not appropriate.

In order to solve the above-mentioned problem, a lower mold, which is a flat mold having no V-shaped convex portion, is provided with a projection orthogonal to the V-groove, so that the lower mold inside the mold has a lower surface. The outflow of the glass can be prevented, and the outflow of the forming glass in the V-shaped convex portion can be prevented to some extent. Therefore, the projections on both sides of the molding portion on the press surface of the mold (upper die) and the projections perpendicular to the V-grooves are used in the lower mold, which is a flat mold having no V-convex portion, so that the inside of the mold is Thus, it is possible to suppress the glass flow in the two-dimensional direction, which is more preferable. In addition, it is preferable that the protrusion perpendicular to the V-shaped groove of the lower die is formed in a portion not necessary for the fiber array, for example, in a portion of a cutting margin.

[0014]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. (Example 1: Mold manufacturing method) A slicer was used as a grinding facility, and the shape of the tip of the grindstone was trapezoidal. V
For processing of the convex part, diamond SD # with a trapezoidal tip shape (tip angle 70 °, plane width 0.03 mm) as a grindstone
Using 2000 metal whetstone, rotation speed is 10,000 rpm
m, a processing speed was 20 mm / min, and four rows of eight V-shaped protrusions were formed on a mold material of φ30 mm by cutting several steps.

The flat portion between the V-shaped protrusion and the V-convex portion of the glass stopper has a whetstone tip shape of a trapezoid (tip angle 70 °).
(Degree, plane width: 1.5 mm) using a diamond SD # 2000 metal grindstone having the same specification as the above-mentioned V-convex processing, and the processing conditions were the same as in the V-convex processing. At the time of this processing, a V-shaped projection for stopping glass flow was left when grinding the flat portion.

(Example 2: Press molding) Using a press die manufactured by the method of Example 1, press molding was performed under the following conditions. Nippon NGK Milacron P as molding glass
When molding was performed using C-4 at a molding temperature of 600 ° C., a molding pressure of 1.0 ton, and a molding time of 60 seconds, outflow of the molding glass to the outside was prevented, and a molded product having good transferability was obtained. Was done.

[0017]

As described above, according to the press die according to the present invention, the outflow of the molding material such as molding glass to the outside can be prevented, so that the molding pressure is made uniform and the shape of the mold is reduced. This has the effect of improving transferability.

[Brief description of the drawings]

FIG. 1 is a cross-sectional explanatory view showing an embodiment of a press die (a multi-piece molding die for a fiber array) and a multi-piece molded product according to the present invention, and a graph showing a pressure distribution image thereof.

FIG. 2 is a cross-sectional explanatory view showing an example of a multi-piece molding die of a conventional fiber array, a multi-piece molding formed by the die, and a graph showing a pressure distribution image thereof.

[Explanation of symbols]

10: a large number of molding dies (upper die), 11: press surface,
12 ... V-convex shape part, 13 ... V-convex row group, 14 ... projection, 15
... glass for molding, 16 ... cutting margin part.

Continued on the front page (72) Inventor Kazutoshi Toyama 2-56 Suda-cho, Mizuho-ku, Nagoya-shi, Aichi

Claims (7)

[Claims] 1. A press mold for molding an optical element, wherein a glass for molding is relatively low expansion glass with respect to a mold material, and both sides of a molding portion on a press surface of the mold. A press die for molding an optical element, characterized in that the projections pierce the molding glass at the time of molding and prevent the molding glass from flowing out by providing the projections. 2. The press die according to claim 1, wherein said projection has a V-shaped cross section. 3. The mold according to claim 1, wherein the mold comprises an upper mold and a lower mold, and the projection is present on one of the upper mold and the lower mold.
Press mold as described. 4. The press die according to claim 1, wherein the protrusions are provided only on outermost side portions of the press surface forming portion of the die. 5. A flat mold having no molding portion, wherein a projection is provided in a direction orthogonal to a projection provided on the mold having the molding portion. Press die described in 1. 6. The press die according to claim 1, wherein the optical element is a V-groove substrate for aligning optical fibers. 7. The low expansion glass has a thermal expansion coefficient of 50 × 1.
The press die according to any one of claims 1 to 6, which is ^0-7 / K or less.