JP3012101B2 - Glass optical element molding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass optical element molding apparatus for manufacturing a glass optical element by direct press molding, and more particularly to an energizing electrode of an electric heating type molding apparatus. .

[0002]

2. Description of the Related Art In recent years, a method for producing a lens using optical glass as a material is to obtain a glass optical element having a predetermined performance by precision pressing a heat-softened glass material using a high-precision mold. Is attracting attention.

Various methods have been proposed for a mold and a heating method for a glass material of an apparatus for press-molding the glass optical element. However, a barrel for holding the molding die is formed of a conductive material, and the barrel itself is formed. The energization heating method, which heats the mold and the glass material by applying heat to the mold and heats the mold and the glass material, can heat the mold and the glass material efficiently and uniformly, making it a very suitable heating method for large diameters and multi-cavities. It is. Also, since electricity is directly converted to heat, conversion efficiency is high and power consumption is low. In addition, since the temperature of the body mold itself to be heated can be directly monitored, the temperature of the body mold and the mold can be easily controlled, and the size of the apparatus can be reduced as compared with other heating methods.

[0004] Fig. 2 shows an example of the configuration of a conventional energization heating type mold, body mold and electrodes. The mold 1 is made of silicon carbide (SiC), and the body mold 2 holding the mold 1 is made of silicon carbide (SiC).
And is formed in a cylindrical shape. An electric wire 5 for supplying electric power of about 6 kVA necessary for heat generation to the body mold 2 is mechanically attached to the body mold 2 with a stainless steel screw 7 and a heat-resistant spring 6 via a copper electrode 13. Here, an electric current is applied to the body mold 2 itself to generate heat, and the heat and heat radiation of the heated body mold 2 cause the mold 1 and the glass material 8 to be heated.
Is heated. The temperature of the mold 1 is measured by a thermocouple 11 and is heated to a temperature near the softening point of the glass. After the glass material 8 is softened, the lower shaft 10 is raised via the backup plate 9 to perform molding. . After being pressed and cooled to a temperature below the glass transition temperature, the lower shaft 10
Has been proposed by the present applicant (Japanese Patent Application No. 4-95328).

[0005]

2. Description of the Related Art An electric heating method is a heating method which is very suitable as a method for uniformly heating a molding die and a glass material. However, a heating method is not suitable for a body mold made of a conductive material and a copper electrode. Since the expansion coefficient is different by more than 5 times, the body type and the electrode are hardly adapted. That is, when the temperature is repeatedly increased and decreased, the inside of the copper electrode is deformed, the contact area between the body and the electrode is reduced, and current bias and heat generation occur locally. As a result, the body mold is not heated uniformly, the temperature of the molding die and the temperature of the glass material become non-uniform, and the shape accuracy of the molded lens deteriorates.

Further, in order to heat the body more uniformly, it is desirable to make the current flow uniformly over a wide range of the body. However, since the electrodes must be greatly lengthened,
In particular, it is difficult to increase the diameter of the body mold and increase the number of cavities.

Further, since it is difficult to attach an electrode to the curved surface of the body, there is a problem that the shape and size of the body are limited.

[0008]

SUMMARY OF THE INVENTION The present invention comprises a molding die and a barrel for holding the mold, and the body formed of a conductive material is energized and heated to produce a glass optical element. In a press forming apparatus for performing heat forming, a current-carrying electrode formed of Ag-Cu-Ti or a Cu-Ti alloy and integrated with the die is formed on a part or the entire surface of the die.
An auxiliary electrode made of carbon is superimposed on the current-carrying electrode and mechanically attached with a metal screw and a heat-resistant spring to supply power required for heat generation to the drum.

[0009]

According to the above construction, a current-carrying electrode having a lower resistance than the body material is formed integrally on the surface of the body formed of a conductive material, and the adhesion is extremely strong. Even if the expansion coefficients differ by more than twice, they do not peel. For this reason, the contact area between the body die and the electrode is reduced, so that local current bias and heat generation do not occur locally.

[0010]

Embodiments of the present invention will be described with reference to the drawings. Here, the same components as those in the conventional example are denoted by the same reference numerals.

Experimental Example 1 FIG. 1 is a structural diagram of a mold, a body mold and electrodes. Mold 1
Is silicon carbide (SiC, volume resistivity: 5 × 10 ⁻¹ Ωm)
A SiC film having a thickness of several hundred μm is formed on the molding surface by the CVD method, and the surface of this SiC film is Ra = 1n
Mirror finish to less than m. The body mold 2 holding the mold 1 is made of a carbon-based composite material (volume resistivity: 5 × 10 ⁻⁴ Ωm) containing silicon carbide (SiC) and is formed in a cylindrical shape. The flat portion 2a and the curved surface portion 2 at both ends of the body mold 2
A paste of a metallizing Ag-Cu-Ti alloy is applied to b and 2c, and the paste is fired in a firing furnace in a vacuum to metallize the surface of the body mold to form the current-carrying electrode 3. An auxiliary electrode 4 made of carbon having a thickness of about 2 mm is overlapped on the current-carrying electrode 3, and an electric wire 5 for supplying electric power is mechanically attached with a metal screw 7 and a heat-resistant spring 6.

Here, a heating experiment was performed by supplying power of about 4 kVA at the maximum to the drum mold 2. Conventionally, heat is locally generated from the body-shaped portion between the opposed copper electrodes 13, and the entire body-shaped body is heated by heat conduction of the body-shaped body. On the other hand, in the present experiment, the body mold 2 has a long and wide current-carrying electrode 3, so that the entire body mold 2 generates heat and the whole body mold 2 is heated, so that the body mold 2 can be heated more uniformly than in the past. . In addition, body type 2
Was heated to 700 ° C. or higher, but no abnormality such as deformation and peeling of the current-carrying electrode 3 was observed at all.

Next, PBL 6 (LL) is used as the glass material 8.
F6), outer diameter φ33 mm, wall thickness 6.6 mm, R1
= 35 mm and R2 = 71 mm were molded.
The glass material 8 is set on the lower mold 1 and is heated to 590 ° C. in a non-oxidizing atmosphere (in N ₂ gas) by an electric heating method.
After heating for 240 sec, the pressure was increased to 500 kgf for 120 sec. After press molding, 200
After cooling to a temperature of not more than ℃, the mold was opened and the formed biconvex lens was taken out.

Conventionally, asbestos (difference due to the diameter direction of the optical surface of a part) occurs in the electrode direction of the molded lens, but the molded lens obtained in Experimental Example 1 has no asbestos.
The shape accuracy has been improved to λ / 2 or less.

Experimental Example 2 Next, Experimental Example 2 will be described with reference to the drawings. In FIG. 1, a mold 1 and a body mold 2 used are the same as those in the experimental example 1, and the plane part 2 a and the curved surface part 2 b at both ends of the body mold 2
A paste of a metallizing Cu-Ti alloy is applied to 2c and fired in a firing furnace in a vacuum to metallize the surface of the body mold 2 to form the current-carrying electrodes 3.

Here, a heating experiment was performed by supplying electric power of at most about 4 kVA to the drum mold 2. As in the case of the experimental example 1, the body mold 2
The whole body is heated and the whole body 2 is heated, and the body 2
Was heated more uniformly. In addition, Cu-Ti
The current-carrying electrode 3 formed by metallizing the alloy is made of Ag-
Since the heat resistance temperature is higher than that of the Cu-Ti alloy, even when the body mold 2 is heated to 850 ° C or more, no abnormality such as deformation and peeling of the current-carrying electrode 3 was observed at all, as in Experimental Example 1.

Next, a biconvex lens was press-molded using this barrel mold 2 in the same manner as in Experimental Example 1 to obtain a molded lens having the same characteristics as in Experimental Example 1.

[0018]

As described above, according to the present invention, since the surface of the barrel formed of a conductive material is metallized with Ag-Cu-Ti or Cu-Ti alloy, the surface of the metallized barrel is formed. The electrode itself becomes a current-carrying electrode, and Ag-
Since Cu-Ti or Cu-Ti alloy penetrates into the body material of the body and becomes integral with the body, the adhesion is very strong, and even if the coefficient of thermal expansion differs by more than twice, it does not peel. For this reason, the contact area between the body die and the electrode is reduced, and the disadvantage that the current is locally deviated or heat is generated is eliminated.

Further, since the metallizing process can be applied to the curved surface portion of the body, the shape and size of the electrode can be freely formed. Therefore, a current can be uniformly applied over a wide range of the die, and even if the die becomes large due to an increase in diameter or multi-cavity, the die can be more uniformly heated. Therefore, the molding die and the glass material can be heated more uniformly, the molded lens has no astigmatism, and the shape accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a mold, a body mold, and an electrode of the present invention.

FIG. 2 is a schematic configuration diagram of a conventional energization heating type mold, body mold, and electrodes.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Die 2 Drum 3 Conducting electrode 4 Auxiliary electrode 5 Electric wire 6 Heat resistant spring 7 Screw 8 Glass material 9 Backup plate 10 Lower shaft 11 Thermocouple

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-6-80431 (JP, A) JP-A-6-92659 (JP, A) JP-A-5-294641 (JP, A) JP-A-61- 266321 (JP, A) JP-A-62-292639 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C03B 11/00 C03B 11/12

Claims (1)

(57) [Claims] 1. A press molding apparatus comprising: a molding die and a body die for holding the mold, wherein the body die itself made of a conductive material is energized and heated to heat and mold a glass optical element. Ag-Cu is mainly applied to part or all of the surface of the body mold.
A glass optical element forming apparatus, wherein a current-carrying electrode integrated with the body die made of Ti or Cu-Ti alloy is formed.