JPH05221663A - Method for feeding softened glass and its apparatus - Google Patents

Abstract

PURPOSE:To prevent a defect from causing in a formed product (glass surface). CONSTITUTION:A softened glass 2 melted in a crucible 1 is nipped between one cutting blade 7 and a pressing member 8 arranged oppositely to the cutting blade 7 and cut. Thereby, a glass gob 9 is formed into a shape in which constricted cut ends (9a) and (9b) are always located in one end (on the side of the pressing member 8) of the glass gob 9 by push cutting the molten glass with the one cutting blade 7. As a result, the glass gob 9 it its intact state is dropped onto a mold 6 to always locate the cut parts (9a) and (9b) in the outer peripheral part of the mold 6. A surface defect such as an air bell is not caused.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for supplying softened glass which is softened by heating to a high temperature and cut and supplied to a mold.

[0002]

2. Description of the Related Art Conventionally, in order to cut a glass flow (softened glass) adjusted to a temperature suitable for glass forming and supply it to a mold, a pair of opposing cutting blades are provided at positions where the descending softened glass is sandwiched. Is generally provided, and the pair of cutting blades are reciprocated in the same plane that crosses the softened glass at a right angle, and the softened glass is sandwiched and cut by both cutting blades, and is supplied to the mold.

However, in such a softened glass supplying method, defects called shear marks are generated on the surface of the cut softened glass. For this reason, in the case of manufacturing an optical glass element or the like, a complicated and uneconomical process of grinding a considerable amount of the surface layer and then polishing the surface layer is required to remove the shear mark.

Therefore, conventionally, in order to solve such a problem, for example, a technique disclosed in JP-A-63-256536 has been proposed. This technology is to cut the softened glass with a shear or a wire heated above the softening point of the glass, to prevent the softened glass to be cut from being cooled, and to prevent the occurrence of shear marks. is there.

[0005]

However, according to the above-mentioned prior art, although the softened glass can be prevented from being cooled at the contact surface with the shear, the occurrence of shear marks can be prevented to some extent, but an optical glass element is provided. It was not enough to get the etc.

That is, as shown in FIG.
When the softened glass 2 melted therein is sandwiched by a pair of cutting blades 3 and 4 and cut, it becomes a glass gob 5 having a vertically constricted shape and falls onto a mold 6. Then, the constricted portion 5a of the glass gob 5 which is narrowed and narrowed,
5b is bent when it falls on the mold 6 and entrains air, and defective portions 5c and 5d called folding are generated. By heating the cutting blades 3 and 4, the constricted portion 5
Although it is possible to prevent the a and 5b from being rapidly cooled and solidified, the shape of the glass gob 5 is basically the same in the above-mentioned conventional method, and there is a high possibility that the mold 6 will be folded near the center thereof. In particular, the lower constricted portion 5 that is rapidly cooled by coming into contact with the mold 6
In the case of b, a fold defect 5d often occurs.

If two cutting blades 3 and 4 are used, when the two cutting blades 3 and 4 cross each other, glass is sandwiched between the cutting blades 3 and 4 to form a small piece. It adheres and hardens. Therefore, there is a problem that the small piece adheres to the surface of the glass gob 5, gets caught inside, or causes a surface defect in the next cutting operation.

The present invention has been made in view of the above conventional problems, and an object of the present invention is to provide a method and an apparatus for supplying softened glass that does not cause defects in a molded product (glass surface) during molding. ..

[0009]

In order to solve the above-mentioned problems, according to the present invention, a softening glass is sandwiched and cut, and when the softened glass cut is supplied to a mold, a cutting blade and a cutting blade are arranged facing each other. By relatively moving the pressing member, the softened glass is sandwiched and cut by the cutting blade and the pressing member, and the cut portion of the cut softened glass is supplied while being positioned at the outer peripheral edge of the mold. did.

Further, in a softened glass feeding device for sandwiching and cutting softened glass and feeding the cut softened glass to a mold, a cutting blade and this cutting blade are placed at a position where the softened glass which has been softened by heating and lowered is sandwiched. And a pressing member having a receiving surface for receiving, and position control means for controlling the position of at least one of the cutting blade and the pressing member so as to supply the cut portion of the cut softened glass to the outer peripheral edge of the mold. It was decided to prepare.

[0011]

In the present invention, as shown in FIG. 1, the softened glass 2 melted in the crucible 1 is cut by being sandwiched by one cutting blade 7 and a pressing member 8 arranged opposite to the cutting blade 7. .. The shape of the glass gob 9 cut by such a method is pushed down by the single cutting blade 7,
The constricted cutting portions 9a and 9b due to the cutting always come to one end side (the pressing member 8 side) of the glass gob 9. Therefore, when the glass gob 9 is dropped onto the mold 6 as it is, the cutting portions 9a and 9b are located at the outer peripheral edge of the mold 6, and surface defects such as folds are generated near the outer peripheral portion of the molded product. Can be located at. Further, since the number of cutting blades is one, there is no possibility that a small piece of glass is left between two cutting blades as in the conventional case, and surface defects due to that cause do not occur. Therefore, the molded product is free from defects. Further, even if some surface defects occur on the outer peripheral portion of the molded product, the surface defects can be easily removed by the centering process after molding.

Further, as shown in FIG. 2, by devising the shape of the pressing member 8 and the like, the glass gob 9 is rotated by 90 ° and dropped onto the mold 6, so that the cutting portions 9a and 9b are securely held in the mold 6. You may make it locate in the outer peripheral part of.

[0013]

[Embodiment 1] FIG. 3 shows a softened glass supply device of this embodiment, in which a softened glass 2 is heated to a temperature suitable for cutting by a heater 10 provided on an outer peripheral wall of a crucible 1. .. A nozzle 11 is provided at the lower end of the crucible 1, and the softened glass 2 flows out from this nozzle. Below the nozzle 11, a cutting blade (shear) 12 and a pressing member 1 are provided.
3 are arranged so as to face each other, and the cutting blade 12 is provided by position control means (not shown) composed of a cylinder or the like.
And the pressing member 13 move so that the softened glass 2 is sandwiched and pressed. Further, the pressing member 13 has a heater 14
The temperature of the pressing member 13 can be controlled by adjusting the heater 14 with the temperature controller 15.

The softened glass 2 is cut with a cutting blade 12 and a pressing member 13.
The glass gob 16 formed by cutting by means of drops onto the lower mold 17. A sleeve 18 having a tapered end is provided on the outer periphery of the lower mold 17. Also, the lower mold 1
As shown in FIG. 4, 7 is placed on the rotary table 19, and after the glass gob 16 is supplied onto the lower mold 17, the rotary table 19 rotates to move the lower mold 1
7 moves to the position right below the upper mold to perform the forming process.

An optical element was molded using the above supply device. Using SF type glass as a raw material, the temperature of the softened glass 2 was controlled to be 780 ° C. in the vicinity of the cut portion. Further, the temperature of the pressing member 13 was controlled to 500 ° C. The diameter of the nozzle 11 was 6 mm. Cutting blade 12 and pressing member 13 every 6 seconds
Was driven to cut the softened glass 2 descending. The lower die 17 had a diameter of 5.5 mm, and the sleeve 18 had a taper of 45 ° for molding.

After molding, the outer peripheral portion of the molded product has a diameter of 1 mm.
When centering was performed (0.5 mm on each side), the number of defective products with shear marks on the surface of the molded product was extremely small, about 1%.

The supply device of the present embodiment only needs to change one of the caps (cutting blades) of the conventional device to a pressing member, and hardly causes a defect due to a shear mark with a very small modification cost. It is possible.

[0018]

[Embodiment 2] In Embodiment 1, a defect of about 1% occurs, mainly because the attitude has changed due to rotation or the like while the glass gob 16 is being supplied. In this embodiment, a method of more stably supplying the glass gob 16 will be described.

In this embodiment, the pressing member 21 has a receiving surface 21a for receiving the cutting blade 12, as shown in FIGS.
Is formed in an inclined rectangular parallelepiped shape. The pressing member 21 is provided below the outlet of the softened glass 2 with the receiving surface 21.
It is fixedly arranged so that a is located. Pressing member 21
The material is a material obtained by coating P-BN (pyrrolytic boron nitride) on isotropic graphite by a CVD method, and the wettability with glass is extremely poor and the glass does not fuse. Further, the pressing member 21 is provided with cylindrical heater insertion holes 22 and 23 at two places, and these heater insertion holes 22 and 23 have a heating portion 24a.
Has a cylindrical shape, and the lead wire 24b is inserted into the cartridge heater 24 connected to the temperature controllers 15a and 15b. Thereby, the temperature of the upper part and the lower part of the pressing member 21 can be set separately, and the upper part can be set to a temperature suitable for cutting and the lower part can be set to a suitable temperature, etc. Also,
The position of the lower die 17 is moved to directly below the receiving surface 21a of the pressing member 21 so that the cut glass gob 16 can be easily received. Since the other configurations are similar to those of the first embodiment, description thereof will be omitted.

An optical element was molded using the above-mentioned supply device. Set the temperature of the upper cartridge heater 24 to 730
℃ to 640 ℃, the temperature of the lower cartridge heater 24
Then, molding was performed. The softened glass 2 flowing down from the crucible 1 gradually flows along the pressing member 21. Then, the cutting blade 12 was advanced to cut the softened glass 2 at every predetermined timing. Cut glass gob 1
6 slides down on the receiving surface 21a of the pressing member 21, and the portion which was the lower end (previous cutting portion) and the present cutting portion are positioned on the outer periphery of the lower die 17 and stop. Then, the upper mold was lowered to perform molding.

After molding, the outer peripheral portion of the molded product was centered by 1 mm, and there was no defective product in which a shear mark was found on the surface of the molded product. In the above supply device,
By applying slight vibration such as ultrasonic vibration to the pressing member 21,
Since the glass gob 16 easily slips off the pressing member 21, it is possible to supply the glass gob 16 to the lower mold 17 in a more stable posture.

[0022]

[Third Embodiment] FIG. 7 shows a supply device of the present embodiment.
In this embodiment, the glass round bar 25 is used as a material. The tip of the glass round bar 25 is heated by the heater 26, while a cooling pipe 27 is arranged immediately above the heater 26 so that the other parts are not softened, and the temperature of the cooling pipe 27 is controlled. Oil is drained. Further, the cutting blade 12 is provided immediately below the heater 26 so as to be movable back and forth,
A pressing member 28 having a concave spherical tip shape is provided at a position facing the cutting blade 12. Further, the pressing member 2
A heater 29 is installed so that the heater 8 can be heated. The pressing member 28 is supported so as to move back and forth and rotate 180 ° around the axis. A lower die 30, a sleeve 31, and an upper die 32 are provided at a position between the heater 26 and the heater 29.
2 can move up and down to be molded. The upper and lower molds 30 and 32 have a maximum of 6 by a heater (not shown).
It is possible to heat up to 00 ° C.

The following is a description based on the operation sequence. First, the tip of the round glass rod 25 is heated. At this time, the pressing member 28 is heated in the heater 29. The upper and lower molds 30 and 32 are also heated to a predetermined temperature. Next, when the tip of the glass rod 25 is softened to a viscosity at which it can be cut, the glass rod 25 descends and the tip comes out below the heater 26. After that, first, the pressing member 28 and the cutting blade 12
Moves forward and cuts the tip of the round glass rod 25. At this time, the cutting trace is always located on the outer peripheral portion (left side in FIG. 8) of the pressing member 28 (see FIG. 8). Subsequently, the pressing member 28 moves onto the lower mold 30 and rotates 180 ° to drop the glass gob 33 onto the lower mold 30 (FIG. 9).
reference). Then, the pressing member 28 retreats while rotating 180 ° again and returns to the inside of the heater 29, and the upper mold 32 descends to form the glass gob 33.

When a glass optical element was molded by the above-mentioned supplying device, no surface defect due to a shear mark occurred in the effective diameter. In this embodiment, since the tip of the pressing member 28 is spherical, the glass gob 33 having a shape similar to that of the desired molded product can be supplied to the lower mold 30. Also,
Since the pressing member 28 receives the glass once and then supplies the glass to the lower mold 30, the supply position of the glass gob 33 can be accurately controlled. It is also possible to prevent the glass gob 33 and the lower mold 30 from being scratched by the impact when dropped.

[0025]

As described above, according to the method and apparatus for supplying softened glass of the present invention, the traces of cutting by the cutting blade are always positioned and supplied to the outer peripheral edge of the mold, and thus, the present invention is obtained. No surface defects occur in the molded product. Further, even if a cut mark remains on the outermost periphery of the molded product, it can be easily removed by centering or the like.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a softened glass supply device of the present invention.

FIG. 2 is a schematic configuration diagram of main parts showing a modified example of the softened glass supply device of the present invention.

FIG. 3 is a schematic configuration diagram showing a supply device according to a first embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a molding device equipped with the supply device of the first embodiment.

FIG. 5 is a schematic configuration diagram showing a supply device according to a second embodiment of the present invention.

FIG. 6 is a perspective view showing a main part of the second embodiment.

FIG. 7 is a schematic configuration diagram showing a supply device according to a third embodiment of the present invention.

FIG. 8 is a schematic configuration diagram showing a state at the time of cutting in the supply device of the third embodiment.

FIG. 9 is a schematic configuration diagram showing a state during glass supply in the supply device of the third embodiment.

FIG. 10 is a schematic configuration diagram showing a conventional softened glass supply device.

[Explanation of symbols]

 2 Softened glass 3,4,7,12 Cutting blade 5,9,16,33 Glass gob 6 type 8,13,21,28 Pressing member 9a, 9b Cutting part 17,30 Lower type

Claims (2)

[Claims] 1. When a softened glass is sandwiched and cut, and when the cut softened glass is supplied to a mold, a cutting blade and a pressing member facing the cutting blade are moved relatively to each other, thereby A method for supplying softened glass, characterized in that the softened glass is sandwiched and cut by a pressing member and the cut portion of the cut softened glass is positioned and supplied to the outer peripheral edge of the mold. 2. A cutting blade and this cutting blade at a position for sandwiching the softened glass which has been softened by heating and cut in a softened glass feeding device for sandwiching and cutting the softened glass and feeding the cut softened glass to a mold. And a pressing member having a receiving surface for receiving, and position control means for controlling the position of at least one of the cutting blade and the pressing member so as to supply the cut portion of the cut softened glass to the outer peripheral edge of the mold. An apparatus for supplying softened glass, comprising: