JPS63170229A - Press-molding device for glass lens - Google Patents

Abstract

PURPOSE:To effectively and uniformly heat a cavity part, by surrounding the outer periphery of a cavity die made of a sintered ceramic with a metallic mold made of a W alloy, and supporting the rear side the metallic mold and the die with a die plate. CONSTITUTION:One or more sets of cavity dies 16 and 17 provided with the cavity surface corresponding to the lens surface of a glass lens are inserted into the metallic molds 14 and 15 and held. The dies 16 and 17 are obtained, for example, by sintering and molding a ceramic such as SiC and Si3N4, the metallic molds 14 and 15 around the dies are formed with a W alloy, hence the thermal expansion coefficients of the die and the mold are approximated, and the mechanical strength and thermal conductivity of the cavity part are increased. The rear sides of the metallic molds 14 and 15 and the dies 16 and 17 are supported by the die plates 12 and 13. s a result, the cavity part in a molding chamber 4 can be effectively and uniformly heated by an induction- heating coil 5.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a glass lens press molding device using an induction heating method, and in particular, a press molding device that uses a cavity die formed by sintering ceramics. This invention relates to improving uniform heating of a cavity portion to be formed.

(Conventional technology) In recent years, glass lens forming methods have changed from polishing, which requires a complicated process, to plasticizing a pre-measured glass lump using an induction heating method using high frequency, etc., and processing it using a precision press. In addition to glassy carbon, cavity dies using ceramics such as silicon carbide (SiC) or silicon nitride (Si, N, ) have been proposed. ing.

Conventionally, as a press-molding apparatus for glass lenses of this type, an apparatus as disclosed in Japanese Patent Application Laid-open No. 49-81419 is well known. Currently, a cavity die made of glassy carbon is attached on the opposite side of the body to perform induction heating.

(Problems to be Solved by the Invention) However, although graphite can be heated by induction and has excellent properties such as thermal conductivity and low coefficient of thermal expansion, it is difficult to use it for the cavity part. Due to its low mechanical strength, it may not only be damaged depending on the pressure structure during pressing, but also because the bonding strength of each particle is low.

Separation of particles from the surface occurs, making it difficult to maintain dimensional accuracy over a long period of time.

Therefore, it is preferable to use a sintered ceramic for the cavity part because it provides high surface precision. However, since ceramics cannot be heated by induction, it is difficult to heat the cavity part effectively and more uniformly. The problem was that it couldn't be done.

The present invention was made under the above circumstances.

The purpose is to provide a glass lens press molding device that uses a cavity die made of sintered ceramic to heat the cavity effectively and uniformly. .

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a press molding apparatus for glass lenses using induction heating means. at least one set of cavity dies each having a cavity surface corresponding to a lens surface, a mold that fits and holds the outer periphery of this cavity die, and a die plate that supports this mold and a back surface of the cavity die. , the mold is made of a tungsten alloy.

(Function) That is, by having the above configuration, the present invention has the following features:
Since the cavity die sintered with ceramics is surrounded by a mold made of tungsten alloy, the thermal expansion coefficients of tungsten alloy and ceramics are very similar, and the mechanical strength of the cavity part is improved. In addition to improving thermal conductivity, a part of the outer periphery of the cavity is made of tungsten alloy, which is a mold, so the cavity can be heated effectively and uniformly. It becomes possible to mold glass lenses.

(Embodiment) An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 schematically shows the overall configuration of a glass lens pressing device according to the present invention, in which both upper and lower fixing plates 1.
A molding chamber 4 is formed by sealingly installing a heat-resistant glass tube 3 between the two, and an induction heating coil 5 is wound around the outer periphery of the heat-resistant glass tube 3.

Furthermore, in the molding chamber 4 described above, an upper fixing plate 1 is provided.
an upper support 7 having an inert gas inlet 6 fixed to it;
and a lower support 9 having an inert gas inlet 8 which is vertically movably held by the lower fixed plate 2 and facing each other in the vertical direction, and these supports 7.9, Both upper and lower molds 14.15 are supported through hollow upper and lower heat insulators 10.11 and upper and lower die plates 12.13, and these upper and lower die plates 12.13 and molds 14.15 is tungsten (W
): 90% by weight, nickel (Ni): 4% by weight, molybdenum (Mo): 4% by weight, and iron: 2% by weight.

The upper and lower molds 14.15 described above have cavity surfaces 16a and 1 corresponding to the upper and lower lens surfaces of the glass lens.
At least one set of cavity dies 16.1 with 7a
7 are fitted and held, and these cavity dies 16,
17 is 1. For example, silicon carbide (SiC) is silicon nitride (
si3N4), which is surrounded by the upper and lower molds 14 and 15,
And on the back side, both the upper and lower die plates 12゜13
14.15.
are mold surfaces 14a and 1 forming a part of the circumferential surface of the glass lens.
5a is also used.

Reference numeral 18 in the figure is an inert gas inlet provided in the upper fixed plate 1 so as to communicate with the inside of the molding chamber 4. During the molding cycle of the glass lens from this inert gas inlet 18, the inert gas inlet 18 is shown by the solid line arrow in Figure 1. As shown in FIG. The air is exhausted from the exhaust port 19. Furthermore, W in the figure is a raw material glass placed on the cavity surface 17a of the lower cavity die 17.

By the way, the inert gas inlets 6.8 provided in both the upper and lower supports 7, 9 are mainly for the purpose of air purging before temperature rise, and after pressure molding, a large amount of inert gas is injected into the adiabatic gas inlet 6.8. body 1
The upper and lower cavity dies 16 and 17 can be cooled in a short time by supplying 0.11 mm to the internal spaces 10a and 11a and cooling the portions in contact with the upper and lower die plates 12 and 13. In this way,
The inert gas introduced into the internal spaces 10a, lla of the heat insulator 10.11 passes through the inside of the molding chamber 4 through the exhaust ports 2o, 21 opened on the side surface of the heat insulator 10.11, and passes through the inside of the molding chamber 4 to the lower fixing plate. The air is exhausted from an exhaust port 19 opened at 2.

Note that the present invention is not limited to the above embodiments.

Of course, various modifications can be made without departing from the gist of the invention.

[Effects of the Invention] As is clear from the above description, according to the present invention, in a glass lens press molding apparatus using induction heating means, a cavity die formed by sintering ceramics is surrounded by a mold made of tungsten alloy. Because it is surrounded by a mold, the thermal expansion coefficients of the tungsten alloy and ceramics are very similar, and the mechanical strength and thermal conductivity of the cavity can be increased. Since the mold is made of tungsten alloy, the cavity part can be heated effectively and uniformly, and glass lenses with excellent surface precision can be molded.This glass lens press molding has excellent effects. The device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing an embodiment of a glass lens press molding apparatus according to the present invention. 4... Molding chamber, 5... Induction heating coil, 12.13... Die plate, 14.15... Mold, 16.17... Cavity die. 16a, 17a...Cavity surface, W...Raw material glass.

Claims (2)

[Claims] (1) In a glass lens press molding device using induction heating means, at least one set of cavity dies is sintered and formed of ceramic and has a cavity surface corresponding to the lens surface of the glass lens, and the outer periphery of this cavity die is fitted. 1. A press-molding apparatus for a glass lens, comprising a mold for holding the mold, and a die plate for supporting the mold and the back surface of the cavity die, the mold being made of a tungsten alloy. (2) The glass lens press molding apparatus according to claim 1, wherein the die plate is made of a tungsten alloy.