JPS63170227A - Press-molding device for glass lens - Google Patents

Abstract

PURPOSE:To uniformize the temp. distribution at a cavity part, by discharging an inert gas from the inner space of a hollow insulator being in contact with the vicinity of the outer periphery of the back of a die plate supporting the cavity part. CONSTITUTION:The periphery and back of cavity dies 16 and 17 are surrounded with metallic molds 14 and 15 made of the material to be induction-heated by respective coils 5 and die plates 12 and 13. The hollow insulators 10 and 11 are brought into contact with the vicinity of the outer periphery of the back of the die plates 12 and 13, and an inert gas is introduced into the internal spaces 10a and 11a from the inlets 6 and 8 bored through supporting bodies 7 and 9 and discharged into the molding chamber 4 from communicating grooves 20 and 21. s a result, more heat is deprived from the vicinity of the die plates 12 and 13 than from the central part side of the insulators 10 and 11, and the temp. distribution of the die plate in the radial direction can be uniformized.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a glass lens press molding apparatus using an induction heating method, and in particular relates to improving uniform heating of a cavity portion. be.

(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 (S i C) or silicon nitride (Sx3N4) have been proposed. There is.

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. They are attached to a support made of aluminum and heated by an induction heating coil. At present, the support is simply supported by a solid insulator.

(Problems to be solved by the invention) However, in the case of induction heating,
Since heating is concentrated on the surface near the heating coil, the center of the support is heated toward the inner diameter by heat conduction from the outer diameter, resulting in induction heating as shown in Figure 4. The relationship between the radial high-frequency effective power A of the support and the temperature results in a temperature gradient of temperature curve B.

In the above-mentioned prior invention, since only one set of cavities is not provided at the center of the support, it is difficult to form a cavity when the radius of the cavity, that is, the radius of the glass lens to be molded is small. Although this is not a problem, if the radius of the glass lens becomes large, or if multiple cavities C are provided on the support as shown in Figure 3, the temperature within one cavity C may change. Due to such temperature non-uniformity, the fluidity of the raw material glass differs partially, and as shown in Fig. 3, frustation occurs on the outer diameter side portion a of the support where the glass easily flows. ,on the other hand,
If the glass does not flow easily, the glass does not fill the cavity, which may cause poor elongation or uneven shrinkage of the lens side corners after molding, causing distortion in the lens. There were problems such as the occurrence of

The present invention has been made under the above circumstances, and its purpose is to provide a press molding apparatus for glass lenses that can achieve uniform temperature distribution in the cavity. be.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides a press molding apparatus for glass lenses using induction heating means, in which a cavity corresponding to the lens surface of the glass lens is formed. A mold and die plate made of a material that surrounds the periphery and back side of at least one cavity die having a surface and is heated by induction; a hollow heat insulating body in contact with the vicinity of the outer periphery of the back face of the die plate; and this heat insulating body. an inlet for supplying an inert gas from the outside of the molding chamber to the inner space of the molding chamber, and a support body formed by communicating with the inner space of the heat insulating body, and an exhaust for exhausting the inert gas from the inner space of the heat insulating body toward the inside of the molding chamber. The configuration is such that a means is provided.

(Function) In other words, the present invention has the above configuration,
The periphery and back of the cavity die for molding on the lens surface of the glass lens are surrounded by a mold and die plate that are heated by induction, and a hollow heat insulator is brought into contact near the outer periphery of the back of this die plate, and this heat insulating material is Inert gas is supplied to the internal space of the die plate from outside the molding chamber, and the inert gas introduced into the internal space of the heat insulating body is exhausted toward the inside of the molding chamber, which improves heat conduction from the die plate. Since the heat that escapes from the die plate can be absorbed by the heat insulating body, more heat is absorbed from the outer periphery of the die plate than from the center, thereby making the temperature distribution of the die plate uniform in the radial direction. It becomes possible to do so.

(Example) Hereinafter, an example of the present invention will be described 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 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
and a lower support 9 having an inert gas inlet 8 which is vertically movably held by the lower fixed plate 2 and face each other in the vertical direction, and these supports 7.9, A hollow upper and lower insulator 10.11 communicating with the inert gas inlet 6.8 is attached, and a die plate 12.13 is attached to the upper and lower insulator 10.11. Hollow heat insulators 1o and 11 are in contact with the outer periphery of the back surface of 12 and 13.

Upper and lower die plates 14.15 are respectively supported by the upper and lower die plates 12, 13, and these upper and lower die plates 12.13 and the die 14.15 are made of an inductor made of molybdenum alloy or tungsten alloy. Each consists of a material that is heated.

In addition, the above-mentioned upper and lower molds 14 and 15 have cavity surfaces 16a and 17 corresponding to the upper and lower lens surfaces of the glass lens.
at least one set of cavity dies 16.17 with a
are fitted and held, and these cavity dies 16.1
7 is a sintered molded ceramic such as silicon carbide (S i C) or silicon nitride (S 13 N4), and its periphery is surrounded by the upper and lower molds 14 and 15. The back side is surrounded by the upper and lower die plates 12 and 13, and the upper and lower molds 14 and 15 also serve as mold surfaces 14a and 15a that form part of the circumferential surface of the glass lens.

Furthermore, 18 in Figure 1 is an inert gas inlet provided in the upper fixed plate 1 so as to communicate with the inside of the molding chamber 4. As shown.

The molding chamber 4 is supplied with an inert gas to provide a cooling effect. It is designed to be exhausted from two ports 19. Further, W in FIG. 1 is a raw material glass placed on the cavity surface 17a of the lower cavity die 17.

By the way, the inert gas inlet ports 6 and 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 Internal space 10a of one body 10.11.

11a, and both the upper and lower die plates 12.13
Both the upper and lower cavity dies 16.17 can be cooled in a short time by cooling the parts in contact with the insulators 10.11. The inert gas is applied to the heat insulating body 10.11 and the die plate 12.
13 (in the illustrated example, on the side of the heat insulator 10.11), the air is exhausted from a plurality of communication grooves 20.21 that communicate with the inside of the molding chamber 4, which are radially carved in at least one of the contact surfaces with It has become.

The plurality of communication grooves 20.21 constituting the exhaust means as described above are connected to the inner space 10 of the heat insulator 10.11.
The inert gas is exhausted from a and lla toward the inside of the molding chamber 4, and the shape of these plurality of communication grooves 20.21 is such that the contact area between the die plate 12.13 and the heat insulator 10.11 is at the inner diameter. The die plate 12.13 is formed to be larger on the outer diameter side than the outer diameter side, so that the amount of heat escaping from the die plate 12.13 through the heat insulator 10.11 is larger on the outer diameter side.

Therefore, to explain the present invention in detail, when both the upper and lower die plates 12.13 and the upper and lower molds 14.15 are heated by the induction heating coil 5, the temperature distribution thereof is as follows.
As shown by temperature curve B in the figure, since the area near the outer periphery where the temperature is high is in contact with the heat insulator 10.11, conduction through the heat insulator 10.11 causes the die plate 12.13 to
Heat escapes from. Furthermore, during the molding cycle of the glass lens, inert gas flows into the molding chamber 4 from the inert gas inlet 18, so the heat insulators 10.11 are cooled by this inert gas, and these Die plate 12.
It acts as a heat dissipation member for the vicinity of the outer periphery of the die plate 12, 13, thereby making the temperature distribution in the radial direction of the die plate 12, 13 uniform. At this time, in order not to excessively cool the die plate 12.13 during temperature rise and pressure molding, inert Inert gas is not supplied from the gas inlet 6°8, or the flow rate is relatively small, and when cooling after pressure molding, a large amount of inert gas is supplied to cool down in a short time. Preferably, the inert gas exhaust means for the internal spaces 10a and lla of the heat insulators 10.11 are provided in the portions in contact with the die plate 12.13 to improve the cooling effect, but as shown in FIG. As shown in FIG.
and a plurality of communication grooves 20.21 provided in a portion in contact with the die plate 12.13 may be provided together.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that various modifications can be made without departing from the gist of the present 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, the periphery and back surface of a cavity die that is formed on the lens surface of a glass lens are induction heated. The molding chamber is surrounded by a mold and a die plate, and a hollow heat insulating body is brought into contact with the vicinity of the outer periphery of the back surface of the die plate, and an inert gas is supplied from outside the molding chamber into the internal space of this heat insulating body. Since the inert gas introduced into the internal space of this heat insulating body is exhausted toward the inside of the molding chamber, the heat escaping from the die plate by thermal conduction can be absorbed by the heat insulating body. Provided is a glass lens press molding device that has the excellent effect of making the temperature distribution in the radial direction of the die plate uniform because more heat is taken from the outer circumference of the plate than the center side. It is something that can be done.

[Brief explanation of the drawing]

Fig. 1 is a schematic cross-sectional view showing an embodiment of the glass lens press molding apparatus according to the present invention, Fig. 2 is a cross-sectional view of the exhaust part taken along the line ■-■ in Fig. 1, and Fig. 3 is an induction heating FIG. 4 is an explanatory diagram showing the relationship between the high frequency effective output in the radial direction and the temperature of the cavity support which is the body to be heated in induction heating. 4... Molding chamber, 5... Induction heating coil. 7.9...Support, 6.8...Inert gas inlet, "10.11...
- Heat insulator, 10a, 11a...Inner space, 12.13...Die plate, 14.15...Mold, 16.17...Cavity die, 16a, 17a...Cavity surface, 20 .21... Exhaust means (communicating groove), W... Raw material glass. Applicant's Representative Patent Attorney Takehiko Suzue Figure 1 Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) In a press molding apparatus for glass lenses using induction heating means, a mold made of a material that surrounds the periphery and back of at least one cavity die and is heated by induction, the cavity die having a cavity surface corresponding to the lens surface of the glass lens. and a support formed by a die plate, a hollow heat insulating body in contact with the vicinity of the outer periphery of the back surface of the die plate, and an inlet for supplying inert gas from the outside of the molding chamber into the internal space of the heat insulating body, communicating with each other. A press molding apparatus for a glass lens, comprising: an exhaust means for exhausting inert gas from the inner space of the heat insulator toward the inside of the molding chamber. (2) The exhaust means is formed from a plurality of communication grooves that are radially carved in at least one of the contact surfaces between the die plate and the heat insulator and communicate with the inside of the molding chamber. 2. The glass lens press molding apparatus according to item 1. (3) The plurality of communication grooves are formed so that the contact area between the die plate and the heat insulator is larger on the outer diameter side than on the inner diameter side. A press-molding device for glass lenses as described in 2.