JP2001130919A - Method for cooling glass molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for cooling, capable of improving bumpy deformation formed on the surface of a glass molding due to high pressure cooling air in blowing the air from above to cool the glass molding after press-molding of the molding. SOLUTION: This method for cooling a glass molding is characterized by increasing cooling air pressure gradually from substantially zero to a determined pressure in initial stage not to cause deformation of the glass molding when the glass molding in a form block is cooled by cooling air blow from above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cooling a press-formed glass molded product, and more particularly to a method for efficiently cooling a glass panel for a cathode ray tube immediately after press-forming.

[0002]

2. Description of the Related Art When manufacturing a glass molded product by press-molding a high-temperature molten glass lump, the hot-pressed glass molded product after being pressed is cooled in as short a time as possible and can be taken out from a press-forming apparatus. The glass molded article is cooled by blowing cooling air from above onto the glass molded article in the mold.

An almost rectangular box-shaped glass molded product such as a glass panel for a cathode ray tube is formed by first molding a high-temperature molten glass lump into a molding die provided at a predetermined interval on a table that rotates intermittently in a press molding device. The molten glass lump is pushed by lowering the pressing die to supply the molten glass ingot, and then the pressing die is raised to form.

After press molding, the high-temperature glass molded product in the molding die is sequentially sent to a plurality of cooling positions and cooled by intermittent rotation of the table. In the cooling position, as shown in FIG.
0 falls into the molding die 11, the damper 21 provided in the cooling air blower tube 20 is opened, and the cooling air 23 supplied by the blower 22 or the like is blown at a predetermined pressure from above, so that the cooling air 23 is present in the molding die. The glass molded article 1 is cooled. After a predetermined cooling time, the damper 21 is closed, the cooling air blower tube 20 rises outside the molding die 11, and the glass molding in the molding die is sent to the next position by the intermittent rotation of the table.

[0005]

When the glass molded article is cooled by the cooling method described above, in order to increase the production amount, it is necessary to shorten the cycle time, which is the time interval for intermittently rotating the table of the press forming apparatus. It is necessary to increase the amount of cooling air per unit time. That is, normally, the pressure of the cooling air is increased to increase the amount of the cooling air, but conventionally, since the above-described damper is opened and closed substantially instantaneously by a pneumatic device or the like, the damper is high from the start stage of the cooling cycle. Cooling air at a pressure is blown onto the glass molded product, and the high pressure is applied to the glass molded product that has not yet been solidified to the inside, so that the inner surface is deformed unevenly.

In particular, when the glass molded product is a glass panel for a cathode ray tube, as shown in FIG. 4, since the shape is a substantially rectangular box shape, the high-pressure cooling air blown from above cannot be applied to the glass panel. There is a tendency to flow in a concentrated manner in the direction of the four corners of the face portion serving as the image display surface of No. 1, and the irregular deformation is remarkably exhibited as a convex deformation at the four corners of the face portion. In addition, in the case of a flat CRT glass panel whose outer surface is almost flat, the thickness of the face part is particularly large in the peripheral part of the face part in order to maintain the strength of the cathode ray tube used as a vacuum vessel. Since it is formed thick, it is necessary to further increase the amount of the cooling air described above. However, by blowing the high-pressure cooling air as described above, the irregular deformation becomes more conspicuous.

Since the glass panel for a cathode ray tube is used as an image display portion of the cathode ray tube, particularly strict quality is required for molding accuracy and molding surface quality. Is significantly reduced, and the maximum deformation amount D of the unevenness is actually 0.2 m.
If it is more than m, it will not be practically used as a glass panel for a cathode ray tube. In FIG. 4, the above-mentioned uneven deformation on the inner surface of the image display unit of the glass panel for a cathode ray tube is exaggerated, but the maximum deformation amount D is the maximum from the design target in the periphery of the diagonal axis. It is a dimensional difference.

Accordingly, an object of the present invention is to improve the deformation of a glass molded product when the glass molded product is press-molded and then cooled by blowing cooling air onto the glass molded product from above. Reduce defects during product manufacturing process,
An object of the present invention is to provide a cooling method capable of improving the productivity of a glass molded product.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended for cooling a press-formed glass molded product in a mold by blowing cooling air from above. A method for cooling a glass molded article, characterized by gradually increasing a pressure of cooling air from substantially zero pressure to a predetermined pressure at a start stage of a cooling cycle without causing deformation of the glass molded article.

Further, when the glass molded product is a glass panel for a cathode ray tube, the inner surface is easily deformed due to its shape, especially at the four corners of the face portion on which an image is displayed, as described above, and the molding accuracy is extremely high. Therefore, when the present invention is applied, deformation is suppressed, which is particularly preferable.

Further, in the present invention, when applied to a glass panel for a cathode ray tube, the pressure increasing rate at which the pressure of the cooling air is gradually increased from substantially zero pressure to a predetermined pressure is 100 per second.
It is preferable that the cooling cycle time is 10 seconds or more, and the pressure increasing time at the above-mentioned pressure increasing rate is 11% or more of the cooling cycle time. If the pressure increasing rate is lower than 100 Pa / sec, the glass panel cannot be sufficiently cooled within the time of the cooling cycle, and if it is higher than 300 Pa / sec, the deformation of the glass panel cannot be suppressed.

When a high-temperature glass block is pressed into a glass panel by a pressing tool in a forming tool, the side wall of the glass panel falls down after the pressing tool rises and separates from the glass panel. Since the glass panel is cooled by the press until the surface of the glass panel solidifies to some extent so that it does not collapse, the surface temperature state of the glass panel when the press is separated from the glass panel is almost constant regardless of the size of the glass panel is there. Therefore, the influence of the pressure increase rate in the subsequent cooling cycle on the irregular deformation of the inner surface of the glass panel is almost the same regardless of the size of the glass panel.

Usually, the predetermined pressure suitable for cooling the glass panel for a cathode ray tube is 1 to 2 kPa. Therefore, the pressure increasing time for gradually increasing the pressure of the cooling air from substantially zero pressure to that pressure is 300 Pa / sec. Even if the pressure is gradually increased at the pressure increasing speed, at least about 3.3 seconds is required.
On the other hand, the cooling cycle time varies depending on the size of the glass panel for a cathode ray tube.However, in a glass panel having such a size that the above-mentioned uneven deformation becomes a problem, at least the time required for cooling and the restrictions on productivity, etc. Usually about 10-25
Since the pressure is increased in seconds, the cooling air pressure cannot be increased to the above-mentioned predetermined pressure unless the pressure increasing time at the pressure increasing speed is about 11% or more of the cooling cycle time. After the pressure is increased to the predetermined pressure, the pressure may be maintained at a constant value, or the pressure may be increased within the range of the blowing capacity to enhance the cooling.

As described above, the press forming apparatus has a plurality of cooling positions, and it is most effective to use the cooling method of the present invention at the cooling position immediately after pressing. It may be performed as needed.

[0015]

According to the present invention, after a glass molded product is press-molded,
When cooling the glass molded product in the mold by blowing cooling air from above, if the inside of the glass molded product is not sufficiently solidified at the beginning of the cooling cycle, cool with low pressure cooling air. No deformation occurs. Further, as the inside is solidified, cooling is performed with high-pressure cooling air, so that the glass molded product can be efficiently cooled within a predetermined time.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The cooling method according to the present invention will be described below based on embodiments. Where it overlaps with the previous description,
For the members, the same drawings are used, and the description is omitted.

In this embodiment, as shown in FIG. 3, at the cooling position immediately after press molding, the opening of the damper 21 can be freely controlled by the drive unit 24 of the damper 21 provided in the cooling air duct 20 of the press molding apparatus. It is composed of a servo motor so that it can be used. In the present example, cooling air was blown onto the glass panel for an 80 cm (corresponding to 34 inches) cathode ray tube at the cooling position immediately after press molding by the above-described cooling device configuration.

FIG. 1 is a graph showing the relationship between the cooling air pressure and the cooling cycle time in the cooling method of the present embodiment. The cooling air is applied to the glass panel in the mold immediately after press molding for 10 seconds. The cooling was performed by gradually increasing the pressure from substantially zero to a predetermined pressure of 1.5 kPa.
At this time, the cooling cycle time is 25 seconds, the pressure increasing rate is 150 Pa / sec, and the pressure increasing time is 40% of the cooling cycle time.

FIG. 2 is a graph showing the relationship between the cooling air pressure and the cooling cycle time in the conventional cooling method for cooling a glass panel for a cathode ray tube having the same size. It is configured to be opened instantaneously by pneumatic equipment such as a cylinder. With this cooling device configuration, the cooling air is applied to the glass panel in the molding die immediately after press molding at substantially zero pressure within one second. And then cooled to a predetermined pressure of 1.5 kPa. The cooling cycle time at this time is 2
5 seconds, the pressure increase rate is 1.5 kPa or more per second, and the pressure increase time is 4% or less of the cooling cycle time.

When the degree of irregularity deformation was examined on the inner surface of the face portion of the glass panel for a cathode ray tube cooled in this way, the maximum deformation of the irregularities of the glass panel for a cathode ray tube cooled by the cooling method of the present invention was examined. The amount D was 0.1 mm or less, and was practically used as a sufficiently good product as a glass panel for a cathode ray tube. On the other hand, the maximum deformation D of the irregularities of the glass panel for a cathode ray tube cooled by the conventional cooling method is about 0.5 mm,
The molding accuracy required for the glass panel for a cathode ray tube was not satisfied at all.

Further, using a glass panel for a cathode ray tube having the same size as that of this embodiment, the pressure increasing rate up to 1.5 kPa is set to 500 Pa, 375 Pa, 300 Pa,
The maximum deformation amount D of irregularities generated on the glass panel for a cathode ray tube was examined by changing to 200 Pa, 100 Pa, and 75 Pa. In this case, the pressure increase time is 12%, 16%, 20%, 30%, and 25% for the cooling cycle time of 25 seconds, respectively.
60% and 80%, and the maximum deformation amounts D are about 0.5 mm, about 0.4 mm, about 0.1 mm, and about 0.1 m, respectively.
m, about 0.1mm, about 0.1mm, 500P per second
At a and a pressure increasing rate of 400 Pa, the deformation amount could not be substantially suppressed. On the other hand, at the pressure increasing rate of 75 Pa per second, the above-mentioned deformation could be suppressed, but the temperature of the glass panel could not be sufficiently lowered within a predetermined cooling cycle time, resulting in insufficient cooling. From the above, 10 per second
It turns out that a pressure increase rate of 0 to 300 Pa is appropriate. Further, it can be seen that increasing the pressure to a predetermined cooling air pressure at a pressure increasing rate of 100 to 300 Pa per second requires a pressure increasing time of 20% or more with respect to the cooling cycle time.

In the above embodiment, an example of a glass panel for an 80 cm cathode ray tube was described. However, as described above, the influence of the pressure increasing rate on the irregular deformation of the inner surface of the glass panel is different from that of a glass panel of another size. But they were almost identical.

According to the present invention, in addition to the glass panel for a cathode ray tube described in the above embodiment, the shape and thickness distribution of the glass molded product may cause irregularities on the inner surface of the glass molded product by the pressure of cooling air. Anything that causes a problem of shape deformation can be used.

In the embodiment of the present invention, the example of the shape of the blow-out portion of the cooling blower tube is shown as a plate, but the present invention can be applied to a simple circular shape, a box-shaped or trapezoidal blow-out portion structure. it can.

[0025]

As described above, according to the method for cooling a glass molded article of the present invention, after the glass molded article is press-molded, cooling air is blown from above onto the glass molded article to cool the glass molded article. It has an excellent effect of improving unevenness of the inner surface of a product to improve productivity of a glass molded product.

[Brief description of the drawings]

FIG. 1 is a graph showing a cooling air pressure with respect to a cooling cycle time according to an embodiment of the present invention.

FIG. 2 is a graph showing a cooling air pressure with respect to a cooling cycle time of a conventional comparative example.

FIG. 3 is an explanatory view showing a cooling state of a glass panel for a cathode ray tube.

FIG. 4 is an explanatory view showing a maximum deformation amount of a concave and convex shape of a glass panel for a cathode ray tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass molded product (glass panel for cathode ray tubes) 11 Mold 20 Cooling blower tube 21 Damper 22 Blower 23 Cooling air 24 Drive part D Maximum deformation

Claims (3)

[Claims] When cooling a press-formed glass molded product in a mold by blowing cooling air from above, the pressure of the cooling air is reduced from substantially zero pressure to a predetermined pressure at a start stage of a cooling cycle. A method for cooling a glass molded product, wherein the temperature is gradually increased and the glass molded product is cooled without causing deformation. 2. The method for cooling a glass molded product according to claim 1, wherein the glass molded product is a glass panel for a cathode ray tube. 3. A pressure increasing rate for gradually increasing the pressure of the cooling air from substantially zero pressure to a predetermined pressure is 100 / sec.
The molded glass article according to claim 2, wherein the cooling cycle time is 10 seconds or more, and the pressure increasing time at the pressure increasing rate is 11% or more of the cooling cycle time. Cooling method.