JP2002316827A - Cooling method and cooling device for glass panel molding for cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve productivity by efficiently cooling a peripheral part while suppressing cooling of the central part of a face section in a pressure molding manufacturing process step for glass panels for cathode ray tubes. SOLUTION: A shielding plate 3 is disposed below a duct 4 for cooling a molding 1 and the cooling air blown off from the duct 4 is blown to this shielding plate 3 and is introduced into the peripheral part 7 of the face section 5, by which the portions exclusive of the portions protected by the shielding plate 3 are preferentially cooled while the cooling of the portions protected by the shielding plate 3 of the face section is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cooling of a molded body immediately after pressure molding in a manufacturing process of a glass panel molded body for a cathode ray tube, and more particularly to cooling of a central portion of the molded body which is protected by a shield plate. The present invention relates to a method and apparatus for effectively cooling other parts.

[0002]

2. Description of the Related Art As a method of manufacturing a glass panel for a cathode ray tube (hereinafter, also referred to as a "panel"), a certain amount of molten glass is supplied to a lower mold, and then the upper mold is lowered to perform pressure molding. In general, a method in which the mold is raised and the molded body is cooled in the lower mold and then taken out is used, and this method will be specifically described below.

[0003] First, a predetermined amount of molten glass mass called a gob is supplied to a lower mold on which an intermediate mold for molding an end of a panel is placed. The lower mold having the gob loaded thereon is subsequently transported to a pressure molding position, at which the upper mold descends, and the gob is pressure molded into a hollow box-shaped panel shape.

At this time, the glass in the lower mold is quenched by the upper mold having a relatively low temperature. However, even after the upper mold rises and the intermediate mold is further removed, the glass panel for a cathode ray tube in the lower mold is removed. The molded body (hereinafter also referred to as a “molded body”) is continuously cooled until the temperature can be taken out of the lower mold. In this case, in a molding apparatus in which a plurality of lower dies are arranged at equal intervals on a rotating disk, this cooling is performed by sequentially rotating the lower die to a plurality of cooling positions by rotating the rotating disk. In each cooling position, the contact surface between the molded body and the lower mold is cooled by the lower mold, and the inner surface of the molded body is cooled by cooling air blown from a duct provided above the lower mold.

[0005] The cooling step will be described in more detail.
While the molded body before removing the intermediate mold is still hot and soft,
Cooling is performed by a device called an air former, which focuses more on preventing the side of the molded product from falling down than on cooling efficiency. The cooling after the removal of the intermediate mold is performed with emphasis on the cooling efficiency, and is usually performed by supplying cooling air from a duct having a circular cross section with a blower and spraying the air on the center of the inner surface of the molded body. .

FIG. 6 is a basic configuration diagram showing a state in which the inner surface of the molded body in the lower mold is cooled, and FIG. 7 is a schematic explanatory view showing a cross section of the molded body. As shown in FIG.
Is placed in the lower mold 2, and in this state, the inner surface is cooled by air sent from the duct 4 disposed above the lower mold 2. When the molded body is sufficiently cooled to such a degree that deformation does not substantially occur in subsequent handling, the molded body is removed from the lower mold and sent to the next step. Then, the lower mold after removing the molded body is sent to the next gob supply position.

As shown in FIG. 7, the molded body 1 has a face portion 5 having a screen for displaying an image and formed in a substantially rectangular shape, and is formed so as to be substantially perpendicular to the face portion 5. And a skirt portion 6 forming a side wall. The end of the skirt 6 has a sealing edge 9.

[0008]

In recent years, the flattening of the image display surface of a cathode ray tube has been rapidly progressing. Accordingly, in the shadow mask type cathode ray tube, since the inner surface needs to have a spherical surface having a relatively large curvature due to its structure, as shown in FIG. The thickness of the portion 7 is designed to be at least twice the thickness of the central portion 8. In other words, the cross section of the face portion 5 has a thickness variation from the center to the periphery, although the thickness distribution is slightly different depending on the orientation.

For this reason, when the molded body is cooled in the manufacturing process, there is a problem that the central portion is overcooled and the peripheral portion is insufficiently cooled due to the uneven thickness. In particular, this phenomenon tends to be further exacerbated when the conventional single duct cooling toward the center of the inner surface (see FIG. 6). Therefore, when the molded body in the lower mold is physically strengthened in this cooling step, a large difference in the reinforcing stress value occurs between the peripheral portion 7 and the central portion 8 of the face portion. Even if the peripheral portion 7 of the face portion has a uniform thickness distribution, it is difficult to cool due to the influence of the skirt portion extending at right angles to the peripheral edge of the face portion, and is relatively thicker than other portions. In addition, since the insufficient cooling caused by the above is further overlapped, the reinforcing stress of the peripheral portion 7 is relatively considerably reduced.

[0010] On the other hand, the cathode ray tube is evacuated and decompressed during use, and the inside thereof is in a vacuum state. Therefore, the envelope has a tensile stress (hereinafter referred to as "tensile vacuum stress") everywhere. ) Occurs. The magnitude and distribution of the tensile vacuum stress vary depending on the shape and thickness of the panel. Looking at the magnitude and distribution of the tensile vacuum stress for the substantially rectangular face portion, the maximum is at the periphery of the outer surface of the face portion, particularly at the ends of the short axis and the long axis. Therefore, in order to allow the panel to withstand the maximum tensile vacuum stress, it is desirable to apply a relatively large reinforcing stress to the peripheral portion of the face portion including the ends of the short axis and the long axis.

However, in the conventional cooling technique, as described above, only a smaller strengthening compressive stress can be applied to the peripheral portion of the face portion such as the central portion of the face portion.
It is difficult to produce panels with the desired physical reinforcement. In particular, it is very difficult to sufficiently physically reinforce a flat panel with a flat outer surface.

The present invention provides a cooling method and a cooling apparatus in which the cooling efficiency is low at the central portion and high at the peripheral portion, particularly for such an uneven thickness panel whose peripheral portion of the face portion is thick. The purpose is to:

[0013]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and particularly, in a manufacturing process of an uneven thickness panel glass in which a peripheral portion of a face portion is thicker than a central portion. When the molded body in the lower mold is cooled, the cooling of the thick part of the molded body is promoted.

That is, according to the present invention, the molten glass is supplied to a lower mold, and then the upper mold is lowered to form the glass under pressure, and then the upper mold is raised to form a duct provided above the lower mold. In a cooling method of blowing cooling air toward the center of the face part inner surface or the vicinity of the center of the face part inner surface of the cathode ray tube glass panel molded body in the lower mold, the cooling air is blown out from the cooling air outlet of the duct and the cathode ray tube glass panel molded body. By hitting against a blocking plate provided between the inner surface of the face and the cooling plate, the direct collision of the cooling air with the cooling suppression region obtained by projecting the blocking plate in the direction of blowing the cooling air on the inner surface of the face portion is suppressed. The present invention also provides a method for cooling a glass panel molded body for a cathode ray tube, which cools a portion other than the cooling suppression region.

Further, the present invention provides a lower mold on which a molded body after pressure molding is mounted, and a duct provided above the lower mold and having a cooling air outlet for blowing cooling air from an opening at a lower end. A blocking plate is provided between the center of the face inner surface of the molded body in the lower mold and the cooling air outlet to prevent the cooling air from directly hitting the center of the face inner surface or its vicinity. The present invention provides a cooling apparatus for a glass panel molded body for a cathode ray tube, characterized by the following.

In the cooling device according to the present invention, the blocking plate is substantially a flat plate or a non-flat plate convex in a direction opposite to the direction in which the cooling air is blown out, and has a cross section perpendicular to the direction in which the cooling air is blown out. The area of a region having the inner wall of the outlet of the duct as the outer periphery is S _D , the area of a region obtained by projecting the blocking plate in the direction of blowing the cooling air is S _B ,
When the opening area of the outer peripheral sealing edge portion inner wall of the glass panel and S _S, it preferably has a _{S D} ≦ S _B ≦ 0.75S S the relationship.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is basically composed of high-speed cooling air from a duct and a blocking plate, but the shape and installation position of the blocking plate are technically important. In general, the shape and installation position of the shielding plate differ depending on the form of the manufacturing equipment, but are common in that they have a shielding function that prevents cooling air from the duct from directly hitting the center of the face of the molded body. are doing. That is, this blocking function suppresses the cooling of the central portion of the face portion, and is a basic function of the blocking plate. Needless to say, in the actual shielding plate, the shape is designed and the installation position is adjusted so that desired cooling can be performed in accordance with product specifications such as the shape and thickness distribution of the molded body.

In a preferred embodiment of the present invention, the shut-off plate is fixedly provided at the end of the duct via a jig, and when the cooling air blown out of the duct hits the shut-off plate, a substantially parallel plate flow is formed. A predetermined interval is provided between the shut-off plate and the duct so that a state flow is obtained. The position of the blocking plate can be roughly divided into two types. The first is a position above the molded body, and the second is a position inside the hollow of the molded body. In order to provide the shielding plate inside the molded body, the duct to which the shielding plate is attached must be lowered from above and inserted. For this reason, in the cooling position of the manufacturing apparatus, the duct moves up and down (hereinafter, referred to as a “vertical mechanism”).
Described below).

Next, the present invention will be specifically described with reference to the drawings. FIG. 1 is a cross-sectional explanatory view showing a basic configuration of the present invention at a cooling position of a manufacturing apparatus, and FIG. 2 is a plan view seen from above in FIG. The molded body 1 at the time of cooling is mounted on the lower mold 2 with the intermediate mold and the upper mold removed after pressure molding as shown in FIG. Above the lower mold 2, a duct 4 equipped with a vertical mechanism is provided toward the center of the molded body 1.
The blocking plate 3 is mounted at a predetermined distance from the cooling air outlet 11 of the duct 4.

When the duct 4 is lowered by the operation of the vertical mechanism in the cooling position, the shut-off plate 3 is also lowered and inserted into the hollow interior 12 of the molded body, and is located at a position where the height from the molded body 1 becomes a predetermined value. Will be retained. In this state, duct 4
When a predetermined flow rate of cooling air is blown out from the cooling plate at a predetermined speed, the cooling air hits the blocking plate 3 and becomes a parallel flat plate-like flow and spreads horizontally along the blocking plate 3, and the blocking plate 3 on the face portion of the molded body 1. The parts other than those protected by are preferentially cooled.
At this time, the cooling air blown out from the duct 4 toward the center of the face portion is blocked by the blocking plate 3, so that the inner surface center portion 8 of the face portion is not directly cooled by the cooling air. As a result, since the cooling of the central portion 8 of the inner surface of the face portion is suppressed, the temperature of this portion is maintained.

Next, a shielding plate useful in the present invention will be described. The blocking plate 3 illustrated in FIGS. 1 and 2 is a rectangular flat plate. Such a flat blocking plate 3 has a simple shape when the blocking plate 3 is inserted into the hollow interior 12 of the molded body 1 and the cooling air flows in the horizontal direction as in the above-described example. Most suitable because it is easy to do. If the shielding plate is inserted into the hollow interior 12 of the molded body 1, the area protected by the shielding plate of the molded body 1 by the cooling air flowing in the horizontal direction along the shielding plate, that is, the inner surface of the face portion Areas other than the cooling suppression area obtained by projecting the blocking plate in the direction in which the cooling air is blown out (hereinafter referred to as “priority cooling area”)
) Can be preferentially cooled.

In order to prevent local cooling of the preferential cooling area, the area of the area obtained by projecting the blocking plate 3 in the direction in which the cooling air is blown out is defined as S _B , and the sealing of the glass panel (molded body 1) is performed. Assuming that the area of the substantially rectangular opening having the edge portion inner wall side 13 as the outer periphery is S _S , S _B ≦ 0.75S _S
It is preferable that they have the following relationship. Further, in order to prevent the cooling suppression region from being cooled more than necessary, the duct 4 in a cross section perpendicular to the direction in which the cooling air is blown out.
When the area of the region to outlet 11 outer circumference an inner wall (inner diameter) of the _{S D,} to have preferably a _{S D} ≦ _{S B,} i.e. _{S D} ≦ _{S B} ≦ 0.75S _S the relationship Is preferred. Note that the relationship between the areas is the same in the case of another shape of the shielding plate described later.

FIGS. 3A and 3B show other shapes of the blocking plate according to the present invention, wherein FIG. 3A is a plan view and FIG. 3B is a cross-sectional view taken along the line AA in FIG. The blocking plate 3 is in the shape of a quadrangular pyramid, and the cooling air sent out of the duct flows along the inclined surface of the quadrangular pyramid after hitting the blocking plate to cool the preferential cooling region preferentially.

FIGS. 4 (a) and 4 (b) show a further different shape of the blocking plate. FIG. 4 (a) is a plan view, and FIG. This blocking plate 3 has a mountain-shaped cross section, and when the ridge of the mountain is used, for example, in accordance with the short axis of the molded body, only the peripheral part on the long axis side of the molded body 1 can be efficiently cooled, and the peripheral part on the short axis side can be cooled. The part is hardly cooled like the central part of the molded body.

In the present invention, the shape of the blocking plate can be appropriately changed as described above. Further, FIGS. 3 and 4 show the blocking plate composed of a plurality of planes. These blocking plates 3 are used to improve the flowability and direction of the cooling air.
For example, a curved surface having a desired curvature and projecting in a direction opposite to the direction in which the cooling air is blown out may be used.

Further, when actually selecting an appropriate shape of the shielding plate 3, the duct of the manufacturing apparatus is provided with a vertical mechanism (not shown).
Is provided, the blocking plate 3 can be inserted into the hollow interior 12 of the molded body, so that any shape of the blocking plate 3 can be applied. However, when the duct 4 is not provided with a vertical mechanism, a non-flat blocking plate that is convex in the direction opposite to the direction in which the cooling air is blown out is used as shown in FIG. 3 or FIG. If the duct 4 is not provided with a vertical mechanism, the blocking plate must be located above the molded body 1. Therefore, in order to guide the cooling air to the peripheral portion 7 of the molded body 1, the shielding plate 3 must have an inclined surface.

In order to preferably cool the molded body 1 by the blocking plate 3 of the present invention, the flow rate of the cooling air from the duct 4 is desirably 50 m / sec or more. This flow rate is the flow rate (about 10 to 40 m /
Second), which is considerably faster. Flow velocity is 50
If the flow rate is less than m / sec, the cooling air blown out from the duct will not form a desirable parallel flat plate flow when hitting the shut-off plate, and the desired cooling effect will not be obtained.
This causes problems such as difficulty in uniform cooling. The flow rate is more preferably 100 m / sec or more.

Further, when the molded body 1 is successively moved to a plurality of cooling positions for cooling, the cooling method of the present invention is usually carried out at each cooling position, but the present invention is applied to only a part of these cooling positions. May be.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cooling device equipped with a flat blocking plate 3 illustrated in FIGS. 1 and 2 was installed at one of the manufacturing devices having a plurality of cooling positions. The duct 4 in this cooling position has a vertical mechanism,
The blocking plate 3 can be pushed down to the hollow interior 12 of the molded body 1. In this state, the molded body 1 mounted on the lower mold 2 is cooled by a cooling device including the duct 4 and the flat blocking plate 3.

The molded body of the 17-inch cathode ray tube panel was cooled by the cooling device. In this panel, the outer surface of the face portion is substantially flat (the radius of curvature is 50,000 mm), the thickness of the central portion 8 of the face portion is about 11 mm, and the thickness of the long axis end portion corresponding to the peripheral portion of the face portion is about 20 mm. The thickness of the end of the diagonal shaft corresponding to the periphery of the portion has a thickness uneven distribution of about 22 mm.

The gap between the blocking plate 3 and the molded body 1 is 80 mm.
The height of the blocking plate 3 at the time of cooling is set so that the distance between the center part 8 of the face of the molded body 1 and the blocking plate 3 is about 20 mm. Also, duct 4
Has an inner diameter of φ50 mm and a cooling air flow rate of 800 Nm ³ /
h, the flow rate of the cooling air was about 113 m / sec, and the time from the start of the blowing of the cooling air to the stop of the blowing was 7 seconds. This cooling device was designated as Example 1 (Example).

On the other hand, the inside diameter of the cooling air blow-out port 11 of the duct 4 of the conventional cooling device having no blocking plate is φ1.
The cooling air flow rate was set to 1000 Nm ³ / h, the cooling air flow rate was set to about 35 m / sec, and the time from the start of the cooling air blowing to the stop of the blowing was set to 8 seconds. This cooling device was designated as Example 2 (Comparative Example). Other conditions were the same as those of the cooling device of Example 1, and the 17-type molded body was cooled to form a panel (panel for cathode ray tube), which was compared with the panel manufactured by the cooling device of Example 1. In Examples 1 and 2,
Since the duct is a small-diameter duct of φ50 mm, the flow velocity can be made high. By applying the high-speed cooling air to the blocking plate 3, a parallel plate flow can be formed.

In the cooling device of the first embodiment, the parallel plate flow is caused to flow along the blocking plate 3 so that the portion of the molded body 1 other than the portion protected by the blocking plate 3, ie, the preferential cooling region. Can be cooled preferentially.
In addition, cooling was suppressed in the center portion 8 of the face portion of the molded body 1 and the cooling effect was almost the same as that of the cooling device of Example 2, and overcooling was prevented.

For this reason, the molded product (panel) cooled by the cooling device of Example 1 was removed from the lower mold although the cooling time was shortened by about 12% as compared with the cooling device of Example 2. Although the temperature of the central portion 8 of the inner surface of the face portion was 20 ° C. higher in Example 1, the temperature of the peripheral corner portion where the cooling was most difficult was almost the same in Examples 1 and 2. From this, it was confirmed that the cooling device of the present invention can efficiently cool the portion (priority cooling region) other than the face portion protected by the cutoff plate as compared with the conventional duct cooling.

Further, the two 17-type molded bodies were respectively cooled by the cooling device of Example 1 of the present invention provided with a blocking plate and the other by the cooling device of Example 2 of the conventional type having no blocking plate. After cooling for about 8 seconds, the two molded bodies were gradually cooled under the same conditions to apply a compressive stress to the molded bodies by the physical strengthening method. Then, for these physically reinforced molded bodies, the reinforced compressive stress on the outer surface of each face portion was measured.

The measurement of the compressive stress is described in
No. 1-281501, specifically, a light source, a deflecting element, a slit, a measurement unit including a first prism and a second prism, and a light-shielding plate disposed between both, and a correction unit. A photoelasticity-based stress measuring device equipped with a detector, an analyzer and an eyepiece was used.

FIG. 5 shows locations where the reinforced compressive stress is measured on the outer surface of the face portion. FIG. 5 is a partially cutaway view of the molded body 1 (glass panel for a cathode ray tube) with the face portion 5 facing upward. The first measurement point is a central portion 21 (short axis 2) of the outer surface of the face portion 5.
2 and the long axis 23), and the second measurement point is a portion 24 near the long axis end of the outer surface of the face portion 5.
Here, the portion 24 near the long axis end refers to a position shifted by 60 mm from the outermost peripheral position 25 at the end of the long axis 23 toward the center of the outer surface of the face portion 5.

As a result, the molded product cooled by the cooling device of Example 1 of the present invention was 14.8 MPa at the center of the face portion.
It was 14.3 MPa in the vicinity of the major axis end, and it was confirmed that a sufficient strengthening compressive stress was also formed in the periphery of the face portion. On the other hand, in the cooling by the duct of the conventional example 2, the pressure was 17.8 MPa at the center of the face portion and 8.4 MPa near the long axis end, and the central portion of the face portion had excessive compressive stress. However, since the peripheral portion of the face portion was not sufficiently cooled, a desired reinforcing compressive stress could not be provided.

[0039]

According to the conventional cooling method and apparatus which do not use a shielding plate, if the flow rate and / or flow rate of the cooling air is increased to cool the peripheral portion of the molded body, the central portion of the face portion is also excessively cooled at the same time. Although there was a problem in cooling the uneven thickness panel in which the peripheral portion was significantly thicker than the central portion due to strengthening, the cooling method and the device of the present invention caused the cooling air from the duct to reduce the cooling air from the face portion. Since it is not sprayed toward the central portion, the peripheral portion of the face portion that is difficult to be cooled can be preferentially cooled while suppressing the cooling of the central portion of the face portion. This prevents overcooling of the central portion of the face portion, and also enables formation of a desired strengthening compressive stress in the peripheral portion of the face portion.

Further, in the cooling method and apparatus according to the present invention, when a blocking plate is provided below the duct and the cooling air blown out of the duct is applied to the blocking plate, the cooling of the central portion of the face portion is promoted. Not only can it prevent, but also can form a parallel plate flow suitable for uniform cooling, and furthermore, it is difficult to cool by guiding this parallel plate flow to the periphery of the face along the blocking plate. The peripheral portion can be efficiently cooled, and the cooling can be simply and appropriately adjusted by changing the shape and position of the blocking plate.

According to the present invention, since the peripheral portion can be efficiently cooled while suppressing the cooling of the central portion of the face portion as described above, the thickness of the peripheral portion of the face portion is significantly larger than the thickness of the central portion. It is particularly suitable for cooling a cathode ray tube panel having a wall distribution.

[Brief description of the drawings]

FIG. 1 is a sectional explanatory view of a cooling device according to an embodiment of the present invention.

FIG. 2 is a plan view of the cooling device according to the embodiment of the present invention described in FIG. 1;

FIG. 3 is another embodiment of the blocking plate of the present invention,
(A) is the top view, (b) is sectional drawing of the AA part of (a).

4A and 4B are still another embodiment of the blocking plate of the present invention, wherein FIG. 4A is a plan view thereof, and FIG. 4B is a cross-sectional view taken along a line BB of FIG.

FIG. 5 is a partially cutaway explanatory view showing a measurement point of a reinforcing compressive stress in the embodiment.

FIG. 6 is an explanatory cross-sectional view of a conventional cooling device that does not use a blocking plate.

FIG. 7 is a sectional view of a molded glass panel for a cathode ray tube.

[Explanation of symbols]

 1: Molded body (glass panel for cathode ray tube) 2: Lower mold 3: Blocking plate 4: Duct 5: Face portion 6: Skirt portion 7: Peripheral portion of inner surface of face portion 8: Central portion of inner surface of face portion 9: Seal edge portion 11: Cooling air outlet 12: hollow interior 21: center of outer face of face 22: short axis of face 23: long axis of face 24: near the end of long axis

Claims (3)

[Claims] 1. The molten glass is supplied to a lower mold, and then the upper mold is lowered to form the glass under pressure. Then, the upper mold is raised and a duct provided above the lower mold is moved into the lower mold. In a cooling method of blowing cooling air toward the center of the face portion inner surface or the vicinity of the center of the face portion inner surface of the cathode ray tube glass panel molded body, the cooling air is blown out from the cooling air outlet of the duct and the face portion inner surface of the cathode ray tube glass panel molded body. By hitting the shielding plate provided between the, while suppressing the direct collision of the cooling air to the cooling suppression region obtained by projecting the shielding plate in the direction of blowing the cooling air, of the face inner surface, A method for cooling a glass panel molded body for a cathode ray tube, comprising cooling a priority cooling area other than the cooling suppression area. 2. A glass panel shape for a cathode ray tube comprising a face portion provided with a substantially rectangular screen and a skirt portion forming a side wall of the face portion and having a seal edge portion at an end portion by molding a molten glass under pressure. A lower mold on which the molded body is mounted, a duct provided above the lower mold and having a cooling air outlet for blowing cooling air from an opening at a lower end, and a face of the molded body in the lower mold A glass panel molded body for a cathode ray tube, wherein a shielding plate for preventing cooling air from directly hitting the center of the face portion inner surface or its vicinity is provided between the center of the inner surface of the portion and the cooling air outlet. Cooling system. 3. The blocking plate is substantially a flat plate or a non-flat plate projecting in a direction opposite to a direction in which the cooling air is blown out, and has a cross section perpendicular to the direction in which the cooling air is blown out. The area of the region having the inner wall as the outer periphery is S _D ,
When the area of a region obtained by projecting the blocking plate in the direction in which the cooling air is blown out is S _B , and the opening area with the inner wall side of the seal edge portion of the glass panel as the outer periphery is S _S , S _D ≦
3. The cooling device for a glass panel molded body for a cathode ray tube according to claim 2, wherein a relationship of S _B ≦ 0.75S _{S is} satisfied.