JPH05254851A - Method for forming optical glass element - Google Patents

Abstract

PURPOSE:To form an optical glass element free from defect. CONSTITUTION:Molten glass 5 is supplied to a transfer member 6 through a nozzle 3. In the above process, the surface of the transfer member 6 is cooled to a temperature lower than the transition point of the supplied glass with a cooling nozzle 7 for sending air from below and the molten glass 5 is cut to a prescribed size and solidified. The solidified glass material 8 in the transfer member 6 is softened and formed with a heater and pressed with a pair of forming molds 10, 11 heated at about the transition point of the glass. The press-formed glass is transferred to an annealing furnace 15, annealed and taken out of the furnace to obtain the objective optical glass element 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding optical glass elements such as lenses and prisms.

[0002]

2. Description of the Related Art As a method for molding an optical glass element, for example, the technology disclosed in Japanese Patent Laid-Open No. 3-60435 is known. That is, while maintaining the molten glass in a non-oxidizing atmosphere, it is supplied to a thermal processing jig which is coated with a chemically stable thin film and has a desired shape and optical surface,
The optical glass molded body that has been thermally deformed on the optical surface of the heat processing jig is press-molded, and each of these steps is carried out in the same device kept in a non-oxidizing atmosphere. Is.

[0003]

However, the above-mentioned conventional technique has the following problems. That is, molten glass is supplied to a thermal processing jig in a non-oxidizing atmosphere, and is thermally deformed to be molded. Molten glass is absorbed into the surface of molten glass by contact with the thermal processing jig. However, there is a problem that cloudy water is generated on the contact surface because the gas expands as gas.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a molding method for obtaining a good optical glass element free from cloudy weather.

[0005]

In order to achieve the above object, the present invention cools the molten glass by supplying the molten glass flowing out from the tip of the nozzle into a conveying member which is cooled by a predetermined amount from below. While supplying and solidifying,
After the supply, the desired optical glass element is formed by the step of heating and softening the glass material in the conveying member and the step of press-forming the heat-softened glass material with a pair of upper and lower molds.

[0006]

According to the above-mentioned forming method, the molten glass flowing out from the nozzle is cooled from the lower side while being supplied into the conveying member, so that the lower surface of the glass is below the transition point of the glass material so that it can be held in the conveying member. It is possible to cool the glass surface, and by holding the part other than the molding surface so that the molding surface is not in contact, the water adsorbed on the surface of the molten glass can be evaporated by heating. Since it is molded, it is possible to obtain a good optical glass element free from defects such as cloudy weather.

[0007]

[Embodiment 1] FIG. 1 is a cross-sectional view of a main part of a molding apparatus 100 for carrying out the optical glass element molding method of this embodiment. In the figure, 1 is a glass melting furnace for melting a glass material, a nozzle 3 for supplying a molten glass 5 into a conveying member 6 is provided below, and a heater 2 and a nozzle heater 4 are provided around the nozzle 3. There is. Inside the molding apparatus 100, a movable conveyor 13 on which a plurality of conveying members 6 are placed is provided. In addition, preheating heaters 16 and 17 for performing a preheating process and heating heaters 18, 19, 20, and 21 for performing a thermal deformation process are provided in the molding apparatus 100. A cooling nozzle 7 for supplying cooling air is provided at a position corresponding to the nozzle 3 of the melting furnace 1 and below the conveying member 6. Reference numerals 10 and 11 denote a pair of upper and lower molding dies, which are provided with heaters 22 and 23 around them, press-mold the glass material 8 in the conveying member 6, cool it in a slow cooling furnace 15, and cool it to a desired optical glass element 14. Is what you get.

Next, the forming method by the forming apparatus in this embodiment described above will be explained using the glass type BAL41 as the molten glass 5.

The nozzle 3 is held in the molding apparatus 100, melted at 1000 ° C. in the glass melting furnace 1, and the molten glass 5 is transferred from the nozzle 3 kept at a nozzle temperature of 740 ° C. in the conveying member 6 which also functions as a barrel. Supply to. The conveying member 6 is preheated to 630 ° C. by the preheating heaters 16 and 17. When supplying the molten glass 5 into the conveying member 6, cooling air is blown from the cooling nozzle 7 while supplying the molten glass 5 to cool the lower surface of the conveying member 6 to a temperature below the glass transition point and cut into a predetermined amount to solidify. ..
The glass material 8 in the solidified conveying member 6 is heated by the heater 1
Heated from above and below at 740 ° C for 5 minutes by 8, 19, 20, 21 to form a shape by heat softening, and then conveyer 1
At 3, the sheet is conveyed between the pair of molds 10 and 11 and press-molded. The mold temperature for press molding was around the transition temperature (535 ° C.) of the glass type BAL41. After the press molding, the glass was conveyed to a slow cooling furnace 15, slowly cooled, and taken out to obtain an optical glass element 14.

With respect to the optical glass element molded by such a process, no defect on the press-molded surface was observed, and it was possible to obtain the one having extremely excellent optical performance.

[0011]

Example 2 In this example, the glass type BAH was used as the molten glass 5.
A case where 30 is used will be described.

The nozzle 3 is held in the molding apparatus 100, melted at 1200 ° C. in the glass melting furnace 1, and the molten glass 5 is transferred from the nozzle 3 kept at a nozzle temperature of 850 ° C. in the conveying member 6 which also functions as a barrel. Supply to. The conveying member 6 is preheated to 630 ° C. by the preheating heaters 16 and 17. When supplying the molten glass 5 into the conveying member 6, cooling air is blown from the cooling nozzle 7 while supplying the molten glass 5 to cool the lower surface of the conveying member 6 to a temperature below the glass transition point and cut into a predetermined amount to solidify. ..
The glass material 8 in the solidified conveying member 6 is heated by the heater 1
Heated from above and below at 740 ° C for 5 minutes by 8, 19, 20, 21 to form a shape by heat softening, and then conveyer 1
At 3, the sheet is conveyed between the pair of molds 10 and 11 and press-molded. The mold temperature for press molding was around the transition point temperature (492 ° C.) of the glass type BAH30. After the press molding, the glass was conveyed to a slow cooling furnace 15, slowly cooled, and taken out to obtain an optical glass element 14.

With respect to the optical glass element molded by such a process, no defect on the press-molded surface was observed, and it was possible to obtain a glass having extremely excellent optical performance.

[0014]

[Embodiment 3] In this embodiment, glass type BAH is used as molten glass 5.
A case of using No. 30 and molding a meniscus lens will be described with reference to FIG.

The nozzle 3 is held in the molding apparatus 100, melted at 1200 ° C. in the glass melting furnace 1, and the molten glass 5 is transferred from the nozzle 3 kept at a nozzle temperature of 850 ° C. in the conveying member 6 which also functions as a barrel. Supply to. The conveying member 6 is preheated to 630 ° C. by the preheating heaters 16 and 17. When supplying the molten glass 5 into the conveying member 6, cooling air is blown from the cooling nozzle 7 while supplying the molten glass 5 to cool the lower surface of the conveying member 6 to a temperature below the glass transition point and cut into a predetermined amount to solidify. ..
The glass material 8 in the solidified conveying member 6 is heated by the heater 1
It is heated at 760 ° C. for 5 minutes from above and below by 8, 19, 20, and 21. The glass material 8 undergoes self-weight deformation by heating and softening as shown in FIG. 2 to form a concave portion on the upper surface and a convex portion on the lower surface. After that, it is conveyed between the pair of molds 10 and 11 by the conveyor 13 and press-molded. The mold temperature for press molding is the transition point temperature of glass type BAH30 (492 ° C)
I went nearby. After the press molding, the glass was conveyed to a slow cooling furnace 15, slowly cooled, and taken out to obtain an optical glass element 14.

With respect to the optical glass element molded by such a process, no defect on the press-molded surface was observed, and it was possible to obtain a glass having extremely excellent optical performance.

In the method for molding an optical glass element of the present invention, the conditions such as the composition of the optical glass, the conveying member, the temperature of thermal deformation, the time, and the shape of the optical glass molded body are the same as those in the above-mentioned embodiments. It is not limited to.

[0018]

As described above, according to the method for forming an optical glass element of the present invention, the optical glass element can be formed in a non-contact manner by supplying the molten glass while cooling it into the conveying member. It is possible to obtain a molded product free from defects such as cloudy weather, which can improve productivity and reduce cost.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a molding apparatus that carries out a molding method according to Examples 1, 2, and 3 of the present invention.

FIG. 2 is a state diagram of self-weight deformation of a glass material in a forming step of a forming method according to a third embodiment of the present invention.

[Explanation of symbols]

 3 Nozzle 5 Molten Glass 6 Inside Transport Member 10 Mold 11 Mold 14 Optical Glass Element

Claims (1)

[Claims] 1. A step of supplying molten glass flowing out from a tip of a nozzle into a conveying member cooled from below by a predetermined amount to supply the molten glass while cooling and solidifying the molten glass, and a glass in the conveying member after being supplied. A step of heating and softening the material,
A method for molding an optical glass element, which comprises molding a heat-softened glass material with a pair of upper and lower molding dies to form a desired optical glass element.