JP2931266B2 - Glass ball manufacturing method and equipment used for it - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a glass ball having a mirror-finished surface and a manufacturing apparatus used for the method.

[0002]

2. Description of the Related Art Conventionally, optical glass having a certain characteristic has been used as a molding material for an optical aspherical lens or the like incorporated in an optical apparatus, but this is formed into a complex lens shape. Requires a polishing process involving a great deal of labor, and therefore, there has been a problem that productivity is low and costs are high. For example, when shaping an optical glass into a predetermined lens shape using a mold, in order to shape the optical glass in the mold without distortion, the optical glass is previously spherical, and its surface is mirror-finished. Must be in a state. For this purpose, it is necessary to form the optical glass into a sphere having a uniform particle size, and to further polish the surface of each particle to a mirror surface. This requires a complicated process and takes an enormous amount of time. Thus, recently, inexpensive lenses using plastic materials that are easy to mold have become widespread, and the demand for them has been growing in place of conventional glass lenses.

[0003]

However, many of the above plastic lenses have a quality such as transparency and optical distortion which is lower than that of glass lenses. Also,
It is pointed out that, although used in large quantities in disposable cameras and DVDs (digital video discs), plastics are not recyclable and cannot be easily disposed of as garbage, causing environmental pollution. For this reason,
It is strongly desired to establish a technique for processing optical glass that can be collected and reused at low cost. Also, with respect to general glass, it is strongly desired to establish a method for obtaining a spherical body having a beautiful mirror surface at a low cost.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for easily and inexpensively obtaining a spherical glass (glass ball) having a mirror-finished surface and an apparatus used for the method. .

[0005]

In order to achieve the above object, the present invention provides a step of dropping molten glass drop by drop from a discharge port provided in a glass melting furnace; A step of sequentially hardening through a plurality of cooling cylinders provided coaxially in the vertical direction to harden into a spherical shape, and allowing the coolant to flow into the plurality of cooling cylinders from the upper edges thereof, At least the flow rate of the cooling liquid flowing into the uppermost cooling cylinder is set to be substantially the same as the passing velocity of the molten glass dripping particles passing through the cooling cylinder, and the cooling liquid used for each cooling cylinder is set. A first gist is a method of manufacturing a glass ball in which the liquid temperature is set so as to decrease from the upper cooling cylinder to the lower cooling cylinder.

Further, the present invention provides a glass melting furnace having a discharge port for dropping molten glass downward one by one, and a plurality of coaxially provided in the vertical direction with the falling trajectory of the molten glass droplets as a central axis. A cooling cylinder, and cooling liquid inflow means for flowing a cooling liquid into the cooling cylinder from an upper edge portion of each cooling cylinder, and at least a flow speed of the cooling liquid flowing into the uppermost cooling cylinder is reduced by the cooling cylinder. While it is set to be substantially the same as the passing speed of the dripped particles of the molten glass passing through the inside, the liquid temperature of the cooling liquid flowing into each cooling cylinder,
A second gist of the present invention is a glass ball manufacturing apparatus which is set to be lower from the upper cooling cylinder to the lower cooling cylinder.

[0007]

Next, an embodiment of the present invention will be described.

FIG. 1 shows a glass ball manufacturing apparatus according to an embodiment of the present invention. In the figure, 1 is
A glass melting furnace for heating a raw glass to a temperature higher than its melting point to melt it into a liquid state. A discharge port 2 for dropping the molten glass one by one downward is provided at the lower center. Under the melting furnace 1, four cooling cylinders 4 to 7 are coaxially arranged in a vertical direction with a falling trajectory of a dropping particle (hereinafter, abbreviated as "dropping particle") 3 of the molten glass as a central axis. Is provided.

A cooling tank 8 is provided around each of the cooling cylinders 4 to 7.
To 11 are provided, and a cooling liquid 12 for cooling and hardening the dropping particles 3 is continuously supplied into each of the cooling tanks 8 to 11. The cooling liquid 12 supplied into the cooling tanks 8 to 11 overflows from the upper edges of the cooling cylinders 4 to 7, flows down in the cooling cylinders 4 to 7, and drops the droplets 3 passing through this portion. And fall down with it.

The upper portion of each of the cooling cylinders 4 to 7 is open in a funnel shape, and the angle (hereinafter referred to as “inclination angle”) formed by the inclined surface of the opened portion with the vertical surface is the upper cooling angle. It is set so that it becomes larger as it goes from the cylinder 4 to the lower cooling cylinder 7. The reason why the inclined surface is provided is that the falling speed of the cooling liquid 12 flowing down in each of the cooling cylinders 4 to 7 is set to the inclination angle θ.
This is for adjusting according to the magnitude of the value. That is, if other conditions are the same, the larger the inclination angle θ is, the slower the flow rate of the cooling liquid 12 flowing down the part becomes. Therefore, a plurality of types of cooling cylinders having different inclination angles are prepared. The flow rate of the cooling liquid 12 can be easily adjusted by appropriately selecting and using it.

The flow speed of the cooling liquid 12 flowing down in the uppermost cooling cylinder 4 is set to be substantially the same as the falling speed of the droplets 3 passing through the cooling cylinder 4. That is, when the liquid droplets 3 are dropped directly into the tank in which the cooling liquid 12 is stored, unless the dropping distance is provided, the droplets 3 are subjected to an impact from the liquid surface in an uncured state. The dripping particles 3 are deformed flat. Therefore, in order to prevent the dripping particles 3 from receiving an impact from the cooling liquid 12, the cooling liquid 12 is dropped while flowing down at substantially the same speed as the falling speed of the dripping particles 3 which are free falling without forming a stationary liquid layer. This is because it was considered that the particles 3 should be brought into contact. In fact,
In this way, even when the drop distance from the discharge port 2 to the uppermost cooling cylinder 4 is as short as 1 m, the droplets 3 come into contact with the cooling liquid 12 while maintaining a true spherical shape due to surface tension, and are cooled and hardened. It falls while falling. However, in the lower cooling cylinder 5 and below, the hardening of the dripping particles 3 proceeds, so that the falling speed of the cooling liquid 12 is gradually reduced to slightly apply a brake to the dripping particles 3 so as to make a slight contact. I have. As a result, the momentum when the dripping particles 3 enter into the falling tank 13 provided further below the lowermost cooling cylinder 7 is weakened, and the dripping particles 3 previously sinking in the falling tank 13 are reduced.
It does not damage the surface due to collision.

As in the above example, the inclination angle θ is
It is set so that it becomes larger from the cooling cylinder 4 to the lower cooling cylinder 7.
The angle of inclination θ (θ₁~ Θ_Four) Size is cold
It depends on the flow rate of the repellent liquid 12 and the cross-sectional area of the flow path at the time of flowing down.
Is usually the inclination angle θ of the cooling cylinder 4. ₁5 to 15 °, cooling cylinder
Angle of inclination θ of 5_Two15 to 25 °, the inclination angle θ of the cooling cylinder 7_Three
25-35 °, the inclination angle θ of the cooling cylinder 8_Four35-50 °
It is preferable to set to.

In each of the cooling cylinders 4 to 7, the coolant 1
The temperature of No. 2 is set so as to decrease from the upper cooling cylinder 4 to the lower cooling cylinder 4. That is, when the falling drop particles 3 are brought into contact with and cured, instead of giving a rapid temperature change, they are cooled stepwise,
This is because it can be cured in a shape closer to a true sphere. For example, when an optical glass ball (softening point 750 ° C.) is produced, the melt of the optical glass is usually set at 900 to 1500 ° C., depending on the material composition. Therefore, as shown in FIG. 1, when cooling is performed in four stages by the cooling cylinders 4 to 7, the temperature of the cooling liquid 12 supplied to the cooling cylinder 4 is preferably set to 650 to 500 ° C. The temperature of the cooling liquid 12 supplied to the cylinder 5 is 500 to 350
° C, the temperature of the cooling liquid 12 supplied to the cooling cylinder 6 is 350 to 2
00 ° C., the temperature of the cooling liquid 12 supplied to the cooling cylinder 7 is 200
It is preferable to set the temperature to ５０50 ° C.

The cooling liquid 12 is preferably a non-combustible oil having a high temperature resistance such as a non-combustible oil for quenching.

Then, the cooling liquid 12 flowing down from each of the cooling cylinders 4 to 7 falls into the falling tank 13 together with the dropped particles 3. The dripping particles 3 are, as already described, the cooling cylinder 4.
7, the liquid is cooled in four stages and is almost completely hardened into a sphere, and falls at a slightly reduced speed, so that the sphere is maintained even if it receives an impact from the liquid surface. Then, when a certain amount of liquid is deposited on the lower part of the falling tank 13, it is taken out from the side. Reference numeral 14 denotes a cushion material adhered to the inside of the falling tank 13 to prevent the dropping particles 3 from receiving an impact in the falling tank 13.

On the other hand, the cooling liquid 12 in the falling tank 13 is refluxed by a reflux pipe 15 connected to the side of the falling tank 13, and passed through pumps 16 to 19 and temperature control means 20 to 23. The coolant is supplied to each of the cooling cylinders 4 to 7 while being adjusted to the flow rate and the liquid temperature.

As described above, according to the above-mentioned apparatus, the glass melt can be dropped one by one and cooled and hardened in a substantially spherical shape by utilizing the surface tension. Moreover,
When the above-mentioned true sphere is formed, it is not damaged from the outside, so that its surface keeps a clean mirror surface, and it is not necessary to perform polishing or finishing after hardening. And
Although the refractive index also depends on the material composition, for example, 1.58 to
An excellent value of 2.2 can be obtained. For this reason, the manufacturing cost can be kept low, and a high-quality glass ball can be provided extremely inexpensively and in large quantities. Therefore, it is most suitable for obtaining an optical glass ball used for molding an optical lens or the like. In addition, the glass ball can be widely used in various fields other than the optical ball, and after use, can be collected and reused. In this respect, it is very advantageous.

The sphericity of the glass ball thus obtained is in the range of 0.7 to 1.0 in terms of Wader's sphericity, and the glass ball has a sufficient spherical shape as a molding material to be applied to a mold or the like. You can see that there is. The diameter of the glass ball is not particularly limited, but it is usually preferable to manufacture a glass ball having a diameter of 1 to 10 mm.

Here, Wardell's sphericity (see Chemical Engineering Handbook, published by Maruzen Co., Ltd.) means the sphericity of particles,
An index measured by [diameter of circle equal to projected area of particle] / [diameter of smallest circle circumscribing the projected image of particle]. The closer this index is to 1.0, the closer to a true sphere. I do.

The surface of the glass ball obtained in this way has a smoothness with a surface roughness (Rmax) of 0.8 to 1.0 μm, and it can be seen that the surface is a very fine mirror surface.

In the above apparatus, the shape of the cooling cylinders 4 to 7 does not necessarily have to have an inclined surface. That is, when the flow rate of the cooling liquid 12 flowing down in the cooling cylinders 4 to 7 is controlled by other factors such as the flow rate and the shape of the inlet, a shape having an inclined surface as shown in FIG. 1 is used. No need. The flow rate of each cooling liquid 12 also needs to be strictly adjusted for the uppermost cooling cylinder 4 in order to match the falling velocity of the dropping particles 3 that fall naturally, The falling speed of the cooling liquid 12 in 5 to 7 does not necessarily need to be lower than the speed of the upper stage, as in the above example, and is appropriately set.

Of course, the number of cooling cylinders 4 to 7 is not limited to four, and any number of cooling cylinders may be used.

Further, the shape of the falling tank 13 and whether or not the cushion material 14 is provided on the inner surface thereof can be appropriately set. And, when the dripping particles 3 can be completely cured by passing through the cooling cylinders 4 to 7, it is not always necessary to provide the drop tank 13,
There is no problem if the dropped particles 3 are directly taken out while being separated from the cooling liquid 12 by a net or the like.

Further, as shown in FIG. 2, a cooling gas atmosphere portion 30 filled with cooling gas is provided between the discharge port 2 of the glass melting furnace 1 and the uppermost cooling cylinder 4, and this portion is passed through. In this way, the droplets 3 may be introduced into the cooling cylinder 4 in a state where the curing of the droplets 3 has been advanced to some extent.

Next, an embodiment will be described.

[0026]

(Composition of glass material)

SiO ₂ 68 wt% Na ₂ O 3.8 〃K ₂ O 10 ＭｇMgO 0.2 〃PbO 15 ＢB ₂ O ₃ 2.0 ＡｌAl ₂ O ₃₁ 〃 [Softening point of glass material] 730 ° C.

This optical glass material was put into a glass melting furnace 1 of the apparatus shown in FIG. 1 to obtain a melt at 1300 ° C.
Then, the apparatus was operated under the following conditions, and glass balls having a diameter of 5 mm were produced at a rate of 1000 pieces / hour.

[Setting of Cooling Cylinders 4 to 7] Inclination angle θ ₁ 15 ° of cooling cylinder 4 Inclination angle θ ₂ of cooling cylinder 5 20 ° Inclination angle θ ₃ of cooling cylinder 4 30 ° Inclination angle θ _{4 of} cooling cylinder 5 40 °

[Setting of the cooling liquid 12] The liquid temperature of the liquid flowing into the cooling cylinder 4 is 650 ° C. The liquid temperature of the liquid flowing into the cooling cylinder 5 is 500 ° C. The liquid temperature of the liquid flowing into the cooling cylinder 6 is 300 ° C. Liquid temperature 100 ℃

The glass ball thus obtained is
Wader's sphericity is 0.8 to 0.9, and its surface roughness (Rmax) is 0.8 to 0.9 µm, and it can be used as it is as a molding material for an optical aspheric lens. there were. And the production cost of this glass ball is 50 times less than that of the conventional one requiring polishing finish.
It has been found that the price is reduced by ~ 60%.

[0031]

As described above, according to the present invention, the glass melt is dropped one by one, and the dropped particles are cured while maintaining the spherical shape by the surface tension. Therefore, the glass ball thus obtained has a substantially true spherical shape, and its surface is a beautiful mirror surface. The refractive index also depends on the material composition, but an excellent value of, for example, 1.58 to 2.2 can be obtained. For this reason, after hardening, there is no need to perform finishing such as polishing, and a high-quality glass ball can be provided extremely inexpensively and in large quantities. The glass ball can be widely used in optical fields or in various other fields. After use, the glass ball can be collected and reused. This is also very advantageous in comparison with plastic molded products. According to the apparatus for manufacturing a glass ball of the present invention, the manufacturing method of the present invention can be efficiently performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a partial configuration of another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass melting furnace 2 Discharge port 3 Dropping particles 4-7 Cooling cylinder 12 Coolant

Claims (4)

(57) [Claims] 1. A step of dropping molten glass drop by drop from a discharge port provided in a glass melting furnace, and dropping the molten glass droplets through a plurality of cooling cylinders provided coaxially in a vertical direction. And a step of hardening into a spherical shape by sequentially passing the cooling fluid into the plurality of cooling cylinders, in which the coolant flows in from the upper edge thereof, and the flow rate of the cooling fluid flowing into at least the uppermost cooling cylinder is reduced. The setting is made so as to be substantially the same as the passing speed of the dropping particles of the molten glass passing through the cooling cylinder, and the liquid temperature of the cooling liquid used for each cooling cylinder is increased from the upper cooling cylinder to the lower cooling cylinder. A method for producing glass balls, which is set to be low. 2. A glass melting furnace having a discharge port for dropping molten glass downward one by one, a plurality of cooling cylinders provided coaxially in a vertical direction with a falling trajectory of the molten glass dripping particles as a central axis, Cooling liquid inflow means for flowing the cooling liquid into the cooling cylinder from the upper edge of each cooling cylinder, wherein at least the flow rate of the cooling liquid flowing into the uppermost cooling cylinder passes through the cooling cylinder. It is set so as to be substantially the same as the passing speed of the dropping particles of the molten glass, and the liquid temperature of the cooling liquid flowing into each cooling cylinder becomes lower as going from the upper cooling cylinder to the lower cooling cylinder. An apparatus for manufacturing a glass ball, wherein the apparatus is set. 3. The upper peripheral wall of each of the cooling cylinders is open in a funnel shape, and the angle formed by the inclined surface with the vertical surface is set to increase from the upper cooling cylinder to the lower cooling cylinder. An apparatus for manufacturing a glass ball according to claim 2. 4. The glass ball manufacturing apparatus according to claim 2, wherein a cooling gas atmosphere portion is provided between the discharge port of the glass melting furnace and the uppermost cooling cylinder.