JPH10203832A - Forming of molten glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing molten glass, capable of reducing waste discarding molten glass every forming without forming shearing mark on the functional face of glass forming product, enabling direct press system capable of producing highly precise glass forming product not requiring post processing and capable of remarkably simplifying the process and forming within short time and remarkably reducing production cost thereby. SOLUTION: This method for forming molten glass, making molten glass 1 housed in a glass melting tank 2 flow from the outlet 4 of the glass melting tank 2 and then, forming the molten glass in a pair of forming molds 13 and 14 comprises a step for cutting the molten glass 1 made to flow from the outlet 4 into a single body 17 and a step for forming a part other than cut part of molten glass cut into the single body 17 in the pair of forming molds 13 and 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 forming a molten glass in which a molten glass is caused to flow out and then formed using a molding die.

[0002]

2. Description of the Related Art Recently, a method of manufacturing a glass molded product (press lens) having high shape accuracy and surface quality which does not require grinding and polishing by simply heating and pressing a glass material is being established. As such a manufacturing method, a manufacturing method applying a direct press method which has been already put into practical use has been considered. This method is shown in FIG.
(B) as (c), the drained molten glass 32 in the viscosity abbreviated to 10 to 10 from the orifice 31 of the glass melting furnace has ³ poise shown, the molten glass 32 of a pair plate shear 33, The molten glass lump (hereinafter, referred to as a gob) 35 is cut at 34 and received by a lower mold 36 and a barrel mold 37 having a relatively low glass transition point temperature or lower, and pressed and formed through an upper mold (not shown). This is a method of producing a glass molded product.

According to the method of manufacturing a glass molded product by the direct press method described above, there is an advantage that the molten glass can be directly received and molded in a mold, but in the case of this method, FIGS. 10 (a) and 10 (c). As shown in FIG. 5, when cutting with a pair of plate-shaped shears 33 and 34, there is an extremely large defect that air bubbles called shear marks 38 are inevitably rolled up and down the gob 35. For this purpose, a shear mark 38 is added to the functional surface of the glass molded product after molding.
For this reason, the direct press method has many advantages but has not been considered as a method for producing a glass molded article that does not require post-processing.

Therefore, for example, Japanese Patent Publication No. 61-32263
In general, a method for forming a preform having improved surface roughness by grinding orifice polishing processing as disclosed in Japanese Patent Application Laid-Open Publication No. H10-209,086 is generally used. The following inventions have been disclosed to solve the drawbacks of the direct press system.

For example, in the invention described in Japanese Patent Application Laid-Open No. 63-248727, a shear mark portion existing at the lower end portion of molten glass discharged from an orifice by a ring-shaped barrel shear and a molding die is not included. After cutting, a method is proposed in which the shaping mark is formed only on the outer peripheral portion of the formed glass molded product and the shaping mark is not generated on the functional surface at all by forming with the forming die and the forming die in the body type shear. ing.

[0006]

However, the above-mentioned prior art has the following problems. Tokiko Sho 61-3226
The invention described in Japanese Patent Publication No. 3 has a problem that the process is complicated as compared with the production method by the direct press method in which a molten glass is directly formed to obtain a glass molded product, and an expensive glass molded product is obtained. ing.

In the invention described in Japanese Patent Application Laid-Open No. 63-248727, although the production cost is reduced by adopting the direct press method, the body-shaped shear is used to avoid fusion with the molten glass. Must be kept in a relatively low temperature range below the glass transition temperature.
On the other hand, the temperature of the mold needs to be in a temperature range of a glass transition temperature or higher in order to improve the surface accuracy of a molded product. For this reason, the temperature control mechanism of the body shear and the molding die becomes complicated, resulting in an increase in machine cost and deterioration in quality. Further, since the shear mark portion existing at the lower end of the molten glass is cut and discarded for each molding, waste of the molten glass occurs. Further, the shape of the molten glass flowing out of the orifice is a free shape determined by the cross-sectional shape of the orifice, the viscosity of the molten glass, its own weight, and the like. Since the difference from the desired product shape is large, the contact between the glass and the mold gradually increases. Therefore, a temperature distribution is easily generated in the glass, and the transferability is deteriorated. Further, useless molten glass may be generated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and an object of the invention according to claim 1 is to prevent a shear mark from being generated on a functional surface of a glass molded product, and to throw away molten glass every molding. Reduced waste, enabling a direct press method that can produce high-precision glass molded products that do not require post-processing, greatly simplifying the process and enabling short-time molding, significantly increasing manufacturing costs An object of the present invention is to provide a method for forming molten glass which can be reduced.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the invention according to claim 1 is to cause molten glass contained in a glass melting tank to flow out of an outlet of the glass melting tank, and then to make a pair. In the method for molding molten glass molded with a molding die, a step of cutting the molten glass flowing out from the outlet into a single body, and molding a portion other than the cut portion of the molten glass cut into the single body with the pair of molding dies. And a step of performing

According to the method for molding molten glass of the invention according to the first aspect, when molding by the direct press method, molding can be performed in which the shear mark by cutting is released outside the optically effective diameter of the molded product. As a result, a shear mark is not generated on the functional surface (effective diameter of the molding surface) of the glass molded product, thereby reducing waste of discarding the molten glass for each molding, and further, a high-precision glass molded product that does not require post-processing. Is obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments will be described.

(Embodiment 1) FIGS. 1 to 5 show Embodiment 1, FIG. 1 is a front view of an apparatus for manufacturing a glass molded article, FIG. 2 is a side view of an apparatus for manufacturing a glass molded article, and FIG. Is A in FIG.
FIG. 4 is a front view in which a part of FIG. 2 is cut away, and FIG. 5 is a cross-sectional view showing a molding process.

In the manufacturing apparatus shown in FIGS. 1 to 4, a heating heater 3 is provided on a side surface of a crucible 2 in which a molten glass 1 is housed. A plunger 5 for adjusting the outflow amount of the molten glass 1 is provided at the upper center of the crucible 2. The outflow port 4 is constituted by a pair of regulating members 7 and 8 and a fixing member 90 which move in opposite directions and function to change the width of the outflowing molten glass 1 '(FIG. 3).
reference). Below the outlet 4 is a sensor 100 for detecting the position of the tip of the molten glass 1 ′, and sends a signal to the controller 11. The restricting members 7 and 8 are configured so that the operation thereof can be arbitrarily controlled by a controller 11 by using air cylinders 9 and 10 (not shown) fixed to the crucible 2 as driving sources. The apparatus relating to the outflow method of the molten glass has been described above. Next, the apparatus relating to the molding of the molten glass will be described.

In FIG. 2, reference numeral 12 denotes a cylindrical sleeve. The sleeve 12 has its radial direction (that is, the outer diameter direction of the molded lens) and the movable direction of the regulating members 7 and 8 coincide with each other. An inlet 12a for molten glass 1 'is provided on the lower side, and an inlet
2a is disposed so as to be located immediately below the outlet 4. The inner diameter of the sleeve 12 is set to an inner diameter equal to the desired outer diameter of the glass molded product, and a pair of molding dies 13 and 14 are slidably fitted inside the sleeve 12. The molding dies 13 and 14 are formed of a heat-resistant material such as SiC or cemented carbide. The molding surfaces 13a and 14a are mirror-finished to a predetermined shape, and then are subjected to chromium nitride (CrN) for preventing fusion with molten glass. ) And boron nitride (BN). The inner peripheral surface 12b of the sleeve 12 is also coated with the same nitride coating as the molding surfaces 13a and 14a.

The clearance between the sleeve 12 and the molding dies 13 and 14 and the length of the insertion part of the molding dies 13 and 14 are set to dimensions such that the inclination between the molding surfaces of the glass molded product becomes a desired value. ing. A pressing portion 15 is fixedly connected to one end surface of the sleeve 12. A hole 15a penetrates through the center of the pressing portion 15, and a push rod 16 is configured to be able to freely enter and exit the hole 15a by a drive source (not shown). Sleeve 1 is provided on the outer peripheral surface of sleeve 12.
2. A heater 18 capable of freely controlling the temperatures of the molding dies 13, 14 and the molten glass lump 17 is provided.

In FIG. 5 showing the molding process, reference numeral 19 denotes a press rod. The press rod 19 is brought into contact with the end faces of the molding dies 13 and 14 by a driving source such as an air cylinder (not shown). And molten glass lump 1
7 is transported and the molten glass block 17 can be pressurized.

In the manufacture of a molded glass article using the apparatus having the above-described structure, first, the molten glass 1 is made to have a viscosity of 10 to 10 ³ poise by the superheater 3 provided in the crucible 2, So that the outer peripheral shape of the molten glass 1 ′ to be formed approximates the shape of the molded product.
In conjunction with the 0 signal, the controller 11 controls the position of the regulating members 7 and 8, and causes the molten glass 1 ′ having an outer peripheral shape approximate to a desired shape to flow out from the outlet 4. Next, it is cut by the shear 6 and the molten glass lump 17 is put between the molding dies 13 and 14 (see FIG. 4). At this time, the shear mark 17a generated by cutting the molten glass block 17 is located above the molten glass block 17, and the shear mark 17b generated by previous cutting is positioned below (see FIG. 5).
), And do not contact the molding surfaces 13a, 14a of the molding dies 13, 14. It is desirable that the temperature of the molds 13 and 14 at the time of this charging be kept in a relatively low temperature region equal to or lower than the glass transition temperature in order to prevent fusion with the molten glass lump 17.

Next, as shown in FIG.
9 is brought into contact with the end face of the molding die 13,
The molten glass block 17 is transferred to the right inside the sleeve 12 by the press rod 19, and
4 are brought into contact with each other. By this transfer, the press rod 1 is placed at a position avoiding the inlet 12a of the molten glass block 17.
A predetermined pressure is applied to the molten glass block 17 by 9 to perform press molding. At this time, since the outer peripheral shape of the molten glass block 17 is almost similar to the shape of the molded product, it is not necessary to cut the outer periphery, and the molding can be completed with a smaller flow of glass. The pressing conditions at this time are as follows:
For example, the heater 18 is controlled to have a temperature of the sag point (viscosity of 10 ^10.5 poise) of the glass, and the pressure is 20 kg / cm ^2.
And then cooled to near the annealing temperature of the glass. After this, push rod 1
6 is brought into contact with the end face of the molding die 14 and is driven to the left to take out the glass molded product 20 from the inside of the sleeve 12.

According to the present embodiment, a high-precision glass molded product 20 that does not require any grinding or polishing is cut while pressing the molten glass 1 flowing out of the orifice 4 of the crucible 2 while approximating the outer peripheral shape. It can be manufactured in a short time and economically by a process as simple as possible to the utmost in molding.

(Embodiment 2) FIGS. 6 and 7 show an embodiment 2, FIG. 6 is a side view showing a part of the apparatus in a cutaway manner, and FIG. 7 is a sectional view taken along the line BB 'of FIG. is there. In the apparatus shown in FIG. 6, components different from those in the first embodiment will be described below, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

The difference from the first embodiment is that the regulating members 7 and 8 are configured so that the cross-sectional shape of the molten glass outlet corresponding to the optical surface direction of the lens shape to be molded can be changed. . The shape of the end surfaces of the regulating members 7 and 8 is approximately the radius of curvature of the optical surface of the molded lens (see FIG. 7). When the molten glass lump 17 flows out, the controller 11 controls the position of the regulating members 7, 8 in conjunction with the signal of the tip position detection sensor 100 so that the optical surface shape of the molten glass 1 'approximates the shape of the molded product. Then, the molten glass lump 17 whose optical surface shape approximates the desired shape from the outlet 4
Spill. The pressure molding of the outflowed molten glass lump 17 is the same as in the first embodiment.
Description is omitted.

According to the present embodiment, since the molding die and the molten glass lump 17 are relatively uniformly formed from the initial stage while being in contact with each other, the temperature distribution inside the glass is reduced, and high precision is achieved. A molded article can be obtained in a short time.

(Third Embodiment) FIGS. 8 and 9 show a third embodiment, FIG. 8 is a side view showing a part of the device cut away, and FIG. 9 is a cross-sectional view taken along the line CC 'of FIG. is there. In the apparatus shown in FIG. 8, components different from those of the first and second embodiments will be described below, and the same reference numerals will be given to the other same components, and the description thereof will be omitted.

That is, this embodiment is different from the second embodiment in the structure of the regulating members 7 and 8 and the control method thereof. In the present embodiment, the regulating members 7a, 7b, 7 that are independently movable within the regulating surface of the molten glass.
c, 7d, 7e and 8a, 8b, 8c, 8d, 8e, and the respective driving sources, air cylinders 9a, 9b, 9c, 9d, 9e and 10a, 10
b, 10c, 10d, and 10e, and their movements are controlled by the controller 11.

When the molten glass 1 'flows out, the position of each regulating member is controlled by a controller in conjunction with a signal from the tip position detection sensor 100 so that the optical surface shape of the molten glass 1' is closer to the shape of the molded product. 11, the molten glass 1 ′ whose optical surface shape approximates to the desired shape can be discharged from the outlet 4.

According to the present embodiment, the second embodiment is described.
Can be further improved.

It is needless to say that by combining the configurations of the first and third embodiments, it is possible to discharge molten glass that is closer to the shape of a molded product.

[0028]

According to the first aspect of the present invention, it is possible to quickly and economically manufacture a high-precision glass molded product that does not require any grinding or polishing.

[Brief description of the drawings]

FIG. 1 is a front view of an apparatus for manufacturing a glass molded product according to a first embodiment.

FIG. 2 is a side view of the apparatus for manufacturing a glass molded product according to the first embodiment.

FIG. 3 is a sectional view taken along the line A-A ′ of FIG. 1 according to the first embodiment;

FIG. 4 is a front view in which a part of FIG. 2 of the first embodiment is partially broken.

FIG. 5 is a cross-sectional view showing a molding step according to the first embodiment.

FIG. 6 is a side view showing a part of the device according to the second embodiment in a cutaway manner.

FIG. 7 is a sectional view taken along the line B-B ′ of FIG. 6 according to the second embodiment;

FIG. 8 is a side view showing a part of the device according to the third embodiment in a cutaway manner.

FIG. 9 is a sectional view taken along line C-C ′ of FIG. 8 according to the third embodiment;

FIG. 10 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molten glass 2 Crucible 4 Outflow port 13 Mold 14 Mold 17 Molten glass lump

Claims (1)

[Claims] 1. A molten glass forming method in which molten glass contained in a glass melting tank is caused to flow out of an outlet of a glass melting tank and then formed by a pair of forming dies. A method for forming molten glass, comprising: a step of cutting molten glass into a single body; and a step of forming a portion other than the cut portion of the molten glass cut into a single body with the pair of forming dies.