JPH08277133A - Formation of glass body - Google Patents

Abstract

PURPOSE: To readily obtain a glass body without any flaw on the surface by using a forming mold having a trumpetlike recessed part and a small hole, placing a molten glass gob in the recessed part while blowing a gas from the small hole so as not to bring the molten glass gob into contact with the inner surface of the recessed part and forming the molten glass gob. CONSTITUTION: This forming mold 1 having a recessed part 2 presenting a trumpetlike shape and a small hole 3 selectively provided so as to open to the central part of the recessed part downward and further <=90 deg. spreading angle θ of the recessed part 2 is prepared. A molten glass gob 4 which is a material to be formed is then received by the recessed part 2 of the forming mold 1 while blowing a gas such as air or an inert gas from the small hole 3 so as to provide a noncontact state of the glass gob with the inner surface of the recessed part 2. The gas such as air or on an inert gas is blown from the small hole 3 so as to afford the noncontact state of the molten glass gob 4 with the inner surface of the recessed part 2. The molten glass gob 4 is rotated in a slightly floated state and sphered to provide a spherical glass body. The inner surface of the recessed part 2 is preferably finished into a mirror surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for directly molding a glass body having no scratches or stains on its surface from molten glass.

[0002]

2. Description of the Related Art Glass bodies such as lenses and prisms are produced by cutting out materials from glass blocks, rods, plates, etc.
It is made by grinding and polishing, or by press-molding molten glass in advance with a mold having a shape similar to the lens, prism, etc. to be manufactured, and grinding and polishing this preformed body. The above-described manufacturing methods for lenses and prisms all require grinding and polishing steps, and thus have a problem of high cost.

A method for directly producing a glass body free from defects such as scratches and stains on the surface from molten glass is disclosed in JP-A-61-14.
No. 6721 is disclosed. In this glass body manufacturing method, the glass melted in the melting crucible is caused to flow out from an outflow pipe provided at the bottom of the crucible, the molten glass is dropped from the tip of the pipe, and the dropping molten glass gob has a surface temperature of that glass. The spherical glass body is produced by allowing the glass surface to fall naturally below its softening temperature, that is, until the glass surface hardens, and then collecting.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The glass body manufacturing method disclosed in Japanese Patent No. 6721 utilizes the surface tension of the glass during spontaneous falling in order to make the molten glass gob dripping from the outflow pipe spherical. However, this manufacturing method has the following problems.

(1) The molten glass gob dripping from the tip of the outflow pipe requires a drop distance of several meters until it cools during the natural fall and the surface hardens. Therefore, a considerable vertical space is required. is necessary. (2) In order to collect a molten glass gob with a considerable drop velocity without scratching the surface, it is necessary to capture the molten glass gob with a highly precise control mechanism that descends in accordance with the drop velocity of the molten glass gob. Collection equipment is required.

An object of the present invention is to provide a glass forming method capable of easily producing a glass body having no defects such as scratches and stains on the surface.

[0007]

In the method of molding a glass body of the present invention to achieve the above object, a trumpet-shaped recess is provided, and the recess is selectively provided so as to open below the center of the recess. Using a molding die having pores, while blowing a gas such as air or an inert gas from the pores so that the molten glass gob that is the object to be molded is in substantially non-contact with the inner surface of the recess. Receiving the molten glass gob by the recess of the mold, and air, a gas such as an inert gas from the pores so that the molten glass gob and the inner surface of the recess are in substantially non-contact state. It is characterized in that the molten glass gob is formed while being blown out.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for forming a glass body of the present invention, as described above, the trumpet-shaped concave portion and the pores selectively provided so as to open below the central portion of the concave portion. A molding die having is used. The concave portion formed in this molding die may have a trumpet shape, but when the molten glass gob to be molded is to be molded into a spherical glass body having a high sphericity, the concave portion shown in FIG. It is preferable that the “divergence angle θ of the recessed portion” is within the range of 5 to 30 °. In addition, reference numeral 1 in FIG. 1 indicates a mold made of heat-resistant steel (for example, stainless steel), and 2 indicates a trumpet-shaped recess, and the “divergence angle θ of the recess” in the mold 1 shown in FIG. Is 15 °. Further, reference numeral 2a in FIG. 1 denotes an inner surface of the concave portion which is finished to be a mirror surface, and 3 denotes a fine hole (diameter 2 mm) selectively provided so as to open below the central portion of the concave portion 2. No. 4 shows a molten glass gob in the middle of molding.

The pores provided in the above-mentioned mold are blown with a gas such as air or an inert gas (for example, N ₂ gas) from the pores so that the molten glass gob to be molded has the above-mentioned structure. The molten glass gob can be received by a mold so as to be substantially in non-contact with the inner surface of the recess, and the molten glass gob can be blown with gas such as air or an inert gas from the pores. As long as the molten glass gob can be molded so that the inner surface of the concave portion and the inner surface of the concave portion are substantially in non-contact with each other, the number and the opening position can be appropriately selected.

When a spherical glass body is to be molded, one fine hole is usually provided so as to open below the central portion of the recess (bottom of the recess). In this case, as shown in FIG. 1, the molten glass gob received by the concave portion of the mold is rotated by the gas blown up from the pores while slightly floating with almost no contact with the inner surface of the concave portion, and is spherical. Be converted.

The molding die may be made of any material that can be used for molding glass, and specific examples thereof include heat resistant steel such as stainless steel. Further, it is preferable that the inner surface of the concave portion of the molding die be mirror-finished so that the surface of the molten glass gob will not be scratched or soiled even if the molten glass gob temporarily contacts. Further, it is more preferable that the inner surface of the concave portion of the molding die is covered with a film of gold, platinum, titanium nitride, or the like, which is difficult to oxidize, except for the opening portion of the pores.

In the method of the present invention, since the molding die having the above-mentioned specific shape is used, a gas such as air or an inert gas is blown out from the above-mentioned pores provided in the molding die to form a molding object. A molten glass gob can be received while being substantially in non-contact with the inner surface of the recess of the mold, and the molten glass gob and the inner surface of the recess of the mold are substantially not in contact with each other. The molten glass gob can be shaped while At this time, the collecting device having a highly accurate control mechanism used in the conventional method is unnecessary. Therefore, according to the method of the present invention, a glass body having no defects such as scratches and stains on its surface can be easily manufactured. The glass body obtained by the method of the present invention can be used, for example, as a material for press molding.

[0013]

Embodiments of the present invention will be described below. Example 1 Using the mold 1 shown in FIG. 1, while blowing 1 liter of air per minute from the pores 3 provided in the mold 1, the concave portion 2 of the mold 1 has a viscosity of 8 poises. The molten glass gob composed of the lanthanum flint-based glass having a predetermined weight heated so that the molten glass gob was molded while continuously blowing 1 liter of air per minute through the pores 3. At this time, the molten glass gob is received by the concave portion 2 of the molding die 1 in a state of slightly floating with almost no contact with the inner surface 2a of the concave portion of the molding die 1, and is rotated in this state to be formed into a spherical shape. It was The spherically shaped molten glass gob was cooled while floating in the recesses 2 and the surface was cooled to a temperature equal to or lower than the softening point and then taken out from the molding die 1. The surface of the spherical glass body thus obtained is free from scratches and dirt, and the weight of the molded glass body is 202 m.
g ± 0.5 mg, with a weight accuracy of ± 0.2%. Further, the sphericity was 4.92 mm ± 0.04 mm with an accuracy of ± 0.8%.

Example 2 Molding was carried out in the same manner as in Example 1 except that a molten glass gob made of a predetermined weight of heavy flint glass heated to a viscosity of 10 poise was used. The surface of the spherical glass body thus obtained was free from scratches and stains, and the weight of the molded glass body was 150 mg ± 0.5 mg.
The weight accuracy was 0.3%. The sphericity is 4.03.
mm ± 0.04 mm, with an accuracy of ± 1.0%.

Example 3 Molding was performed in the same manner as in Example 1 except that a molten glass gob made of a barium heavy crown glass having a predetermined weight and heated to have a viscosity of 10 poise was used. The surface of the spherical glass body thus obtained was free from scratches and stains, and the weight of the molded glass body was 308 mg ± 1 mg,
The weight accuracy was ± 0.3%. Also, the sphericity is 5.6.
It was 3 mm ± 0.05 mm and had an accuracy of ± 0.9%.

Example 4 Molding was carried out under the same conditions as in Example 1 except that the spread angle θ of the recess 2 of the molding die 1 was changed to 7 °. The surface of the spherical glass body thus obtained was free from scratches and stains, the weight and weight accuracy of the molded glass body were the same as in Example 1, and the sphericity was 4.93 mm ± 0.03 mm. ,
The accuracy was ± 0.6%.

Example 5 Molding was performed under the same conditions as in Example 1 except that the divergence angle θ of the recess 2 of the molding die 1 was changed to 30 °. The surface of the spherical glass body thus obtained was free of scratches and stains, the weight and weight accuracy of the molded glass body were the same as in Example 1, and the sphericity was 4.92 mm ± 0.04 mm. , ± 0.8% accuracy.

Example 6 Molding was performed under the same conditions as in Example 1 except that the divergence angle θ of the recess 2 of the molding die 1 was changed to 90 °. The sphericity of the spherical glass body thus obtained was 4.92 mm ± 0.46.
mm, with an accuracy of ± 9.3%.

In any of the above fourth to sixth embodiments,
The surface of the obtained spherical glass body was free from scratches and stains, and the weight and the weight accuracy were the same as in Example 1, but the sphericity was such that the spread angle θ of the concave portion 2 of the molding die 1 was up to 90 °. When it spreads, it deteriorates significantly.

[0020]

As described above, according to the glass body molding method of the present invention, it is possible to easily manufacture a glass body having no surface defects such as scratches and stains.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a molding die used in Example 1.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Mold, 2 ... Trumpet-shaped recess, 2a ... Inner surface of recess, 3 ... Pores, 4 ... Molten glass block.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuhiko Kaneko 2-7-5 Nakaochiai, Shinjuku-ku, Tokyo Inside Hoya Co., Ltd. (72) Inventor Shigeru Asanuma 2-7-5 Nakaochiai, Shinjuku-ku, Tokyo Hoya Corporation

Claims (5)

[Claims] 1. A molding die having a trumpet-shaped concave portion and a fine hole selectively provided so as to open below the central portion of the concave portion is used. Air is blown from the pores so as to be substantially in non-contact with the inner surface of the recess, while the molten glass gob is received by the recess of the mold while blowing a gas such as an inert gas.
And, the molten glass gob is molded while blowing a gas such as air or an inert gas from the pores so that the molten glass gob and the inner surface of the recess are substantially in a non-contact state. A method of forming a glass body. 2. The spread angle of the trumpet-shaped recess is 9
The method according to claim 1, wherein a mold of 0 ° or less is used. 3. The method according to claim 1, wherein a molding die in which the inner surface of the recess is mirror-finished is used. 4. The method according to claim 1, wherein the molten glass gob is formed into a spherical glass body. 5. The method according to claim 1, wherein a glass body as a material for press molding is produced.