JPS6015581B2 - How to obtain molten glass lumps for high temperature molding - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining hot moldable molten glass gobs.

Glass molded products, such as TV cathode ray tube panels or funnels, are made by extruding molten glass in a melting furnace through an orifice discharge hole provided at the bottom of the spout of a feeder, and cutting it with a cutting blade to obtain a predetermined amount of molten glass for molding. It is produced by forming a glass gob (hereinafter referred to as a gob) and feeding the gob into a mold of a molding machine.

However, when forming such glass, the most important point is that the glass be in a soft, low-viscosity state at a high temperature that is compatible with gobs and forming.

The high-temperature molten glass melted in the melting furnace and led to the feeder remains in the feeder and spout for a considerable period of time, and the temperature of the glass decreases due to heat radiation. In the process of being extruded from the hole, cut by a cutting blade, turned into gobs, and supplied onto the mold of a forming machine, the glass temperature is lowered by being directly exposed to the external atmosphere and being cooled.

This decrease in the temperature of the molten glass and therefore the gob, that is, the change in viscosity, is
This is a particular problem when manufacturing small molded products.

In other words, when manufacturing a large molded product by using an orifice with a size and a discharge hole to form a large gob, the amount of molten glass flowing out is large, and the molten glass is trapped inside the feeder and spout. The time to fill up is relatively short,
In addition, since there is little influence from the external atmosphere during the gop formation and supply process, the gop supplied to the molding machine is maintained at a high temperature and has a viscosity that matches the molding conditions, allowing it to be molded without hindrance to molding. .

However, when manufacturing small molded products by forming small gobs using an orifice with four holes and a discharge hole, the amount of molten glass flowing out is small, and the molten glass does not flow into the feeder or spout. The glass remains for a long time, resulting in large heat loss due to heat radiation, and the gob formation process is strongly influenced by the external atmosphere, causing the glass temperature to drop rapidly, causing the gob supplied to the molding machine to become difficult to mold. Does not maintain proper viscosity,
Therefore, not only is molding impossible or difficult, but even if molding is possible, the quality of the molded product is impaired, resulting in a defective product. Molding problems due to insufficient viscosity of the gob caused by such a drop in glass temperature become more pronounced as the molded product becomes smaller. Therefore, in order to increase the temperature of the gop when manufacturing the above-mentioned molded products, especially type 4,
The following methods are possible.

That is, first, after an effective gob is supplied to the molding machine, molten glass is not allowed to flow out from the discharge hole of the orifice for gop forming until the next effective gob is supplied to the molding machine. The second method is to heat the molten glass in the spout of the feeder with gas or electricity, and the third method is called "bottom drain." Possible methods include discharging a portion of the molten glass from the bottom of the feeder or spout. Therefore, the temperature of the gob can be raised for several minutes by the above method. However, in the first method, when molding products are continuously molded in large quantities using a molding machine equipped with a plurality of molds on a rotary table, the molten glass flows out from the discharge hole of the orifice during the effective gob feeding interval. In this method, there is a limit to the increase in gob temperature due to the time constraints and the small amount of molten glass flowing out, and with this method alone, it is not possible to obtain a gob with a viscosity that is particularly suitable for small molded products. do not have. The second method requires additional heating equipment, and the heat loss due to heat radiation from the molten glass increases rapidly as the flow rate of the molten glass decreases. must be increased to However, it is very difficult to control this heating, resulting in large fluctuations in gob temperature and gob weight, making it impossible to repeatedly obtain gobs with a viscosity and weight suitable for continuous molding. Furthermore, in the third method, the temperature of the molten glass rises up to the position where it is bottom drained, but the molten glass remains in the spout and orifice after that position for a long time as before, and the temperature decreases due to heat radiation. As a result, the effect of temperature rise cannot be expected much. The object of the invention is to provide a method for obtaining hot gobs with a viscosity suitable for molding, for example when manufacturing particularly small panels or funnels of TV cathode ray tubes.

In the method of the present invention, when cutting molten glass extruded from the discharge hole of an IJ orifice to form a gop for molding, a discharge hole is provided in the orifice separately from the discharge hole for forming the gop. The present invention is characterized in that a high-temperature molding tube is obtained by allowing the molten glass in the orifice to flow out from the discharge hole.

Next, the present invention will be specifically described according to embodiments shown in the drawings.

The drawing shows an example of a gob forming device, where 10 is a spout provided near the tip of a feeder (not shown) that guides molten glass 11 melted in a melting furnace, and 12 is a closed part at the bottom of this spout. Fireproof orifice installed at the bottom end, 1
3 is a discharge hole of the orifice 12; 14 is a pair of cutting blades 16 for cutting the molten glass 11 extruded from the discharge hole 13 of the orifice 12 to form a molding gob 15;
1 is a rotating sleeve for feeding the molten glass 11 in the spout 10, and 17 is a needle provided in the rotating sleeve for pushing out the molten glass from the discharge hole 13 of the orifice 12.

Note that the rotating sleeve 16 and the needle 17 are normally arranged coaxially with the discharge hole 13 of the orifice 12. In such a gob forming device, the molten glass 11 in the spout 10
The molten glass 11 is forced out from the discharge hole 13 of the orifice 12 by moving the needle 17 up and down while being homogenized by the rotating sleeve 16, and is cut by the cutting blade 14 to form a gob 15. (not shown) onto a mold.

The present invention provides an orifice 1 in the gob forming method described above.
2 is provided with a discharge hole 18 for discharging the molten glass 11 in the orifice 12 to the outside, in addition to the discharge hole 13 through which the molten glass to be formed into a glass lump or gob is extruded. A suitable amount of molten glass 11 is always allowed to flow out.

The discharge hole 18 provided in the orifice 12 is preferably provided at a position that does not interfere with the forming operation and the gob forming operation, for example, the operation of the cutting blade 14. The size of the discharge hole 18 is of course selected and applied for the intended purpose of obtaining a gob with a viscosity suitable for molding, but it is preferable to make it equal to the discharge hole 13. In this way, if the discharge hole 18 is provided separately from the discharge hole 13, the molten glass 11 will continue to flow out from the discharge hole 18 even while extrusion of molten glass for forming from the discharge hole 13 is stopped. 1
The total amount of molten glass 11 flowing out from 2 is much larger than when there is only discharge 13.

Therefore, the molten glass 11 does not accumulate in the spout 10 and the orifice 12 for a long time, and the high-temperature molten glass is continuously supplied into the orifice 12. When the gob is formed, a high-temperature gob having a viscosity suitable for molding can be obtained even if it is cooled by the external atmosphere during the process of extrusion from the discharge hole 13 until it becomes the gob 15 and is supplied to the molding machine. become. Next, the effect of increasing the gob temperature according to the present invention will be explained using specific numbers.

When using an orifice with only the discharge hole on the closed diameter 25 side, the glass temperature inside the spout should be 1250 at the highest point.
Even though it was set to 0.0, the temperature dropped rapidly, the viscosity increased rapidly, and the gob temperature was only 900 qo or less, and this temperature also fluctuated by 150 qo, making it difficult to mold. I couldn't get a gob with vine viscosity.

Moreover, even if I tried to get a gob of 50 yen, the weight varied between 18 and 12 yen. On the other hand, when using an orifice implementing the method of the present invention in which a discharge hole with an opening diameter of 20 mm was provided in an orifice equipped with a discharge hole of the same diameter as the above, although the glass temperature in the spout was suppressed to 115,000, figure,
It had a temperature of 1100 oo and a viscosity suitable for molding, and it was possible to repeatedly obtain 50 gobs with no variation in weight. In addition, in the embodiment described and illustrated above, one discharge hole is provided in the orifice, but the number of discharge holes is not limited to this, and a high temperature gofu can be obtained even if there is a larger number. Similar effects can be expected. In connection with the present invention and the prior art, I would like to add just in case that there is no discharge hole, which is a requirement of the present invention, but an orifice with multiple discharge holes (generally called a "double orifice"). )
There is. This is for the purpose of increasing production. Multiple discharge holes of the same shape are provided symmetrically on the horizontal lower surface of the bottom of the orifice, and at the same time multiple gops used for molding are formed. It differs from an invention in purpose and structure.
When carrying out the method of the present invention, if it is desired to obtain a gob with a lower viscosity at a higher temperature, the above-mentioned method can be used to increase the temperature of the gob, for example, after feeding an effective gob to a molding machine. It is preferable to use a method in which the molten glass continues to flow out from the gob-forming discharge hole of the orifice until the next effective gob is supplied to the molding machine.

In addition, the molten glass that flows out from the discharge hole of the orifice and the molten glass that is discharged from the discharge hole and is not used for molding as described above should be carefully placed so that it does not interfere with the molding operation and falls onto the molding machine. In order to avoid this, the cullet is received by the cullet chute during its flow and is used again as a raw material for glass.

According to the method of the present invention described above, when manufacturing a relatively large molded product in a gob forming apparatus equipped with mechanisms and operations such as a spout, an orifice, a rotating sleeve, and a needle, it is possible to When manufacturing relatively small molded products using an orifice with only a discharge hole,
By simply replacing the orifice with an orifice that has a discharge hole for discharging the molten glass inside the orifice in addition to the discharge hole, a high-temperature gob suitable for molding even small molded products can be obtained. For example, the present invention has an effect that can be advantageously applied to the production of small molded products such as TV cathode ray tubes.

[Brief explanation of drawings]

The drawing is an explanatory cross-sectional view showing an example of a goboo forming device for carrying out the present invention. In the drawings, 1 is a spout, 11 is a molten glass, 12 is an orifice, 13 is a discharge hole, 14 is a cutting blade, 15 is a gob of molten glass for molding, and 18 is a discharge hole.

Claims (1)

[Claims] 1. In a method of cutting molten glass extruded from a discharge hole of an orifice provided at the bottom of a spout of a feeder to form a molten glass lump for molding, a discharge hole is provided in the orifice provided with the discharge hole, and a discharge hole is formed from the discharge hole. A method for obtaining a high-temperature molten glass lump for molding, characterized by flowing out molten glass in an orifice.