JP2009057214A - Lower die for molding cathode ray tube glass panel and method for producing cathode ray tube glass panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve productivity by mounting a shielding plate and a straightening plate in a lower molding die to strengthen the cooling of a periphery part in a pressure-molding step to produce a glass panel for a cathode ray tube. <P>SOLUTION: The lower molding die for the glass panel for the cathode ray tube has a hollow part shaped by a nearly rectangular bottom 3 and side walls 4 at four sides of the bottom, wherein the glass panel 1 for a cathode ray tube in the hollow part is cooled by a coolant supplied from the lower part of the bottom 3 to the central part of the bottom 3. The supercooling at the central part is prevented and the cooling of the peripheral part is strengthened by providing the shielding plate and the straightening plate on the bottom part 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is a lower mold for forming a cathode ray tube glass panel, and in particular, by providing a shielding plate and a rectifying plate below the bottom, when cooling from below the bottom, the center of the bottom is supercooled The present invention also relates to a lower mold for molding a glass panel for a cathode ray tube capable of strongly cooling the peripheral portion at the bottom, and a method for producing a glass panel for a cathode ray tube using the lower mold for molding.

  Conventionally, when a glass panel for a cathode ray tube (hereinafter simply referred to as a panel) is molded, a predetermined amount of molten glass lump (hereinafter referred to as a gob) is supplied to a lower mold for molding (hereinafter simply referred to as a lower mold). Next, after lowering the upper mold for molding (hereinafter simply referred to as the upper mold) and pressurizing the gob to mold it, the upper mold is raised, and after the molded panel is cooled in the lower mold, the panel is taken out. The method is common. Hereinafter, this method will be specifically described with reference to the drawings.

FIG. 5 is an explanatory plan view showing a molding flow in a molding apparatus for a cathode ray tube glass panel.
A series of molding of the panel described above is usually obtained by a molding apparatus in which a plurality of lower molds 2 are arranged at equal intervals on a rotating disk 16 as shown in FIG. First, at a position, a predetermined amount of gob is supplied to the lower mold 2 on which an intermediate mold for molding the end of the panel is placed. The lower mold loaded with the gob is subsequently moved to the pressure molding position b, and the upper mold is lowered at the pressure molding position, and the gob is pressure molded into a glass panel molded product for a cathode ray tube of a hollow box type. The

  At this time, since the upper mold is relatively low in temperature as compared with the gob, the temperature of the gob in the lower mold rapidly decreases. And while the upper mold | type raises and the turntable 16 rotates intermittently further, the panel in a lower mold | type is cooled, and even after the intermediate mold | type is removed from the lower mold | type in e position, each cooling position f? Sequentially transferred to i and cooled sufficiently to the extent that deformation does not occur in subsequent handling. Thereafter, the cooled panel is taken out from the lower mold at the j position and sent to the next process. And the lower mold | type after taking out a panel is sent to the first gob supply position a in preparation for the next shaping | molding.

  In each cooling position, the outer surface of the panel in contact with the lower mold is cooled through the contact surface with the lower mold. Further, the inner surface of the panel is cooled by a coolant such as cooling air (hereinafter referred to as cooling air) blown out from a duct provided above each cooling position. At this time, a circular nozzle is installed at the bottom of each cooling position of the molding apparatus toward the bottom of the lower mold, and the lower mold is cooled by cooling air blown upward from the nozzle.

  FIG. 6 is a cross-sectional explanatory view of a conventional lower mold for forming a glass panel for a cathode ray tube, which cools the bottom of the lower mold. As shown, the lower mold 2 on which the panel 1 is placed is fixed to the turntable 16 via a mounting flange 8 by a plurality of legs 7 provided on the bottom 3 thereof. The bottom of the lower mold is cooled by the cooling air blown out from the nozzle 12 arranged below. The cooling air from the nozzle 12 first collides with the center of the bottom through the space surrounded by the legs 7 and then flows to the periphery.

  Since this cooling air is a substantially circular collision jet directed toward the center of the bottom 3 of the lower mold 2, the cooling air has a mountain-shaped heat transfer coefficient distribution with the central stagnation point as a peak. Due to such a heat transfer coefficient distribution, the temperature of the bottom of the lower mold is low in the central part and high in the peripheral part, so that the cooling of the peripheral part of the panel 1 is relatively weak. Therefore, if the supply amount of the cooling air is increased in order to lower the temperature of the peripheral part of the lower mold 2, the temperature of the central part is lowered more than necessary to cause overcooling, which causes remarkable deterioration of moldability.

  In order to solve such a problem, Japanese Patent Application Laid-Open No. 2000-351638 discloses that the shape of the outlet for supplying cooling air toward the bottom of the lower die is made substantially rectangular, so that the lower die can be made uniform efficiently. A cooling method has been proposed.

  However, the cooling air supplied from the outlet of the cooling device described in Japanese Patent Application Laid-Open No. 2000-351638 is a slit-like impinging jet directed toward the center of the bottom of the lower mold, so that the stagnation at the center It is still a mountain-shaped heat transfer coefficient distribution with a peak point, and it is difficult to eliminate the lack of cooling around the lower mold.

  Japanese Patent Application Laid-Open No. 2004-277278 proposes a method for improving productivity by enhancing the cooling of the peripheral part by insulating the center part of the lower mold.

  However, the method described in Japanese Patent Application Laid-Open No. 2004-277278 is superior to the conventional method but is still insufficient.

JP 2000-351638 A (see FIGS. 1 to 4) JP 2004-277278 A

  In recent years, flattening of the image display surface of a cathode ray tube has been progressing rapidly. In the cathode ray tube of the type having a shadow mask, the inner surface of the panel needs to have a spherical shape having a relatively large curvature because of its structure. Therefore, as shown in FIG. The part 13 may be designed so that the thickness of the peripheral part is more than twice the thickness of the central part.

  That is, the cross section of the face portion 13 has a slight thickness distribution difference depending on the orientation such as the minor axis, the major axis, and the diagonal axis, but the thickness from the central portion 14 toward the peripheral portion 15 in any orientation. It becomes the uneven thickness shape which increases. Such a face panel is called an uneven thickness panel.

  This uneven thickness makes it difficult for the peripheral portion of the thick panel to be cooled, so that when the panel is cooled in the manufacturing process, the central portion 14 is overcooled and the peripheral portion 15 is insufficiently cooled. The temperature distribution of the lower mold at that time tends to be relatively insufficiently cooled at the peripheral portion even if the central portion of the bottom surface is sufficiently cooled as described above.

  In addition, due to the recent drop in the price of cathode ray tubes, an increase in production tact for the purpose of cost reduction is required.

However, if the cooling time is shortened with conventional equipment, the periphery of the lower mold becomes insufficiently cooled. For example, in the process of removing the panel at the position j as shown in FIG. 5 from the lower mold, the panel sticks to the lower mold and cannot be removed. The production tact was difficult because it was a fatal problem in production.
For this reason, the invention of the lower mold | type which can accelerate | stimulate cooling of a peripheral part more is desired, preventing the supercooling of the center part of a lower mold | type.

  The present invention has been made in view of the above circumstances, and cools a lower mold in a manufacturing process of a glass panel for a cathode ray tube, particularly an uneven panel in which the peripheral part thickness of the face part is larger than the central part thickness. In this case, an object of the present invention is to provide a lower mold capable of reducing the temperature distribution at the bottom of the lower mold, and a method of manufacturing a glass panel for a cathode ray tube using the lower mold.

  In order to achieve the above object, the invention according to claim 1 has a glass filling portion for forming a cathode ray tube glass panel formed by a substantially rectangular bottom portion and side wall portions provided on four sides of the bottom portion, A cathode ray tube glass panel molding lower mold that cools a cathode ray tube glass panel molding in a glass filling portion with a refrigerant supplied from below the bottom portion to a central portion of the bottom portion, and is below the bottom portion, and the refrigerant A shielding plate in the horizontal direction in accordance with the horizontal center of the lower mold, and below the bottom, at the upper end of the refrigerant blowing hole, and outside the shielding plate The lower die for forming a cathode ray tube glass panel is provided with a current plate in the vertical direction.

  The invention according to claim 2 is characterized in that the lower shielding plate for molding a cathode ray tube glass panel according to claim 1 has a central hole.

  According to a third aspect of the present invention, the hole in the lower shielding plate for molding a cathode ray tube glass panel according to the first or second aspect is substantially circular, and the diameter of the hole is 10 mm or more and 30 mm or less. It is a feature.

  Invention of Claim 4 is 1 mm or more of the gaps between the bottom part of the lower mold | die for cathode-ray tube glass panel shaping | molding of any one of Claims 1-3, and the surface facing the said bottom part of the said baffle plate, It is characterized by being 20 mm or less.

  The invention according to claim 5 is a cathode ray tube glass panel molded article by supplying molten glass to a lower mold for forming a cathode ray tube glass panel formed by a substantially rectangular bottom and side walls provided on four sides of the bottom. In the method of manufacturing a glass panel for a cathode ray tube, the coolant is supplied toward the center of the bottom of the lower mold, and the glass molded product filled in the lower mold is cooled. 4. A cathode ray tube glass panel, wherein the lower mold for forming a cathode ray tube glass panel according to any one of 4 is used.

  According to the present invention, when cooling the lower die for cooling the molded product of the cathode ray tube glass panel in the manufacturing process of the cathode ray tube glass panel, the peripheral portion thereof is not supercooled without overcooling the central portion of the lower die bottom. It is possible to provide a lower glass panel mold for a cathode ray tube and a manufacturing method capable of relatively strongly cooling the glass. The present invention is particularly suitable for lower cooling of a large-sized cathode ray tube panel having a size of 29 or more, for example, having a thickness distribution that is significantly larger in the peripheral part of the face part than in the central part, Among them, it is particularly suitable for varieties having an aspect ratio of 16: 9.

  In addition, even if the cooling time is shortened, the periphery of the lower mold becomes insufficiently cooled, and in the process of taking out the panel at position j as shown in FIG. 5 from the lower mold, the panel sticks to the lower mold and cannot be taken out. It does not occur and productivity can be improved.

  Next, the structure of the lower mold | type of the glass panel for cathode-ray tubes of this invention is demonstrated in detail based on an Example.

  Generally, when cooling air is blown onto the lower surface of the bottom center of the lower mold and the lower mold is cooled by the impinging jet, the heat transfer coefficient distribution at the bottom has a peak shape that peaks at the stagnation point at the bottom center as described above. become. Therefore, it is effective to install a shielding plate below the lower mold in order to avoid overcooling at the center of the bottom, and it is also effective to install a rectifying plate to promote cooling of the periphery. Is. That is, in the present invention, as a means for adjusting the temperature distribution at the bottom of the lower mold, a shielding plate and a current plate are provided below the bottom of the lower mold.

  In the present invention, the shielding plate is provided in a central portion below the bottom of the lower mold so as to obtain a predetermined effect. Since the bottom of the lower mold is a rectangular shape that is substantially similar to the shape of the face of the panel, the central portion of the bottom of the lower mold is the rectangular central portion, specifically, the rectangular bottom portion. This is a region within a predetermined range from the center of the bottom where the major axis and the minor axis intersect. The present invention is characterized in that a shielding plate having a predetermined thickness is provided in this region in parallel with the bottom portion with a predetermined distance from the bottom portion. In addition, the shielding plate is provided with a hole through which a part of the cooling air passes, and prevents excessive heat retention in the lower mold central portion. As the position of the hole, the central portion of the shielding plate is preferable from the viewpoint of objectivity.

  In the present invention, the shape when the shielding plate is vertically projected is not limited. In the present invention, the planar shape of the shielding plate refers to this vertical projection shape. The planar shape may be a rectangular shape, a polygonal shape, or the like in addition to a circular or elliptical substantially circular shape. However, since the legs for mounting and fixing to the molding apparatus are generally arranged in a circular shape around the center of the bottom part on the bottom surface of the bottom part of the lower mold, the substantially circular shielding is usually in the area surrounded by the legs. It is preferable to provide a plate. When the shielding plate is provided at the center of the bottom surrounded by the legs in this way, it is easy to attach the shielding plate to the legs. Moreover, the shielding plate should just be installed between the lower mold | type bottom part and the blowing hole of the air which cools a lower mold | type, and it is more preferable that the distance of a lower mold | type bottom part and a shielding plate is about 20 mm.

  As for the diameter of the hole drilled in the shielding board in this invention, 0-30 mm is preferable. This is because if the thickness is less than 10 mm, the heat retention at the center of the lower mold becomes excessive, and if it is greater than 30 mm, the cooling at the center of the lower mold becomes too strong.

  On the other hand, for example, the current plate is formed by processing a metal plate having a thickness of 2 to 5 mm into a ring shape, and the lower mold bottom and the surface facing the lower mold bottom of the current plate are outside the shielding plate. Install to form a 20 mm gap.

  In the present invention, the gap between the bottom of the lower mold and the surface facing the bottom of the rectifying plate is preferably 1 to 20 mm. However, if the gap between the lower mold bottom and the rectifying plate exceeds 20 mm, the cooling air speed is sufficient. This is because the cooling effect is reduced, and if it is less than 1 mm, the pressure loss is too large and the cooling air does not sufficiently flow, and the desired cooling effect cannot be obtained. Further, the rectifying plate only needs to be installed between the bottom of the lower die and the air blowing hole for cooling the lower die, so that air does not escape below the rectifying plate, for example, as shown in FIG. It is preferable that the mounting flange 8 with holes is abutted or embedded.

  Further, the gap between the bottom of the lower mold and the current plate need not be the same value over the entire circumference, and the long side portion and the short side portion may have different values.

  As described above, a part of the cooling air from the blowout hole passes through the center of the hole formed in the shielding plate and collides with the central portion of the bottom, and then flows to the peripheral portion, and the rest of the cooling air is applied to the shielding plate. Along the current plate, then collides with the peripheral part of the bottom of the panel along the current plate, and finally flows outside the gap between the current plate and the panel.

  Next, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is a plan view of a lower mold that is a preferred embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line AA of FIG. The lower mold 2 has a substantially rectangular glass filling portion formed by a substantially rectangular bottom portion 3 and a side wall portion 4 extending in a direction perpendicular to the periphery of the bottom portion 3. When the panel is actually molded, an intermediate mold (not shown) is placed on the side wall portion 4 and used on the side wall portion 4.

  In order to facilitate the flow of the cooling air in the major axis direction among the major axis and minor axis directions and 45 directions intermediate between the major axis and minor axis direction, the bottom portion 3 has six directions excluding the major axis two directions. Six legs 7 are arranged at fixed positions from the center of the bottom 3, that is, are arranged in a circle around the center of the bottom 3, and the lower ends of these legs 7 are attached to the mounting flanges 8. It is fixed. By attaching the mounting flange 8 to the turntable 16, the lower mold 2 is fixed to the molding apparatus. In this embodiment, the number of the legs 7 is six as described above. However, when measures are taken to facilitate the flow of cooling air in the long axis direction, such as narrowing the legs in two long axis directions, There may be eight legs 7.

  In the panel molding process, after gob pressure molding, the cathode ray tube glass panel molded product 1 placed on the glass filling portion of the lower mold 2 passes through an air blowing hole 9 provided at the center of the mounting flange 8. The bottom 3 of the lower mold 2 is first cooled by the cooling air blown from the outlet 12 to the bottom 3 of the lower mold 2, and then the outer surface of the panel 1 is cooled through the contact surface of the bottom 3.

  As shown in FIGS. 1 and 2, a shielding plate 5 is provided at the center portion surrounded by the lower legs 7 from the bottom 3 of the lower mold 2. An air blowing hole 10 having a diameter of 10 mm to 30 mm is formed in the center of the shielding plate. In this case, the shielding plate 5 has an arm 11 for fixing to the leg 7 and is fixed to the leg 7. The material of the shielding plate 5 may be metal, but stainless steel is particularly preferable.

  On the other hand, the rectifying plate 6 is installed so that the gap between the bottom 3 of the lower mold 2 and the surface of the rectifying plate 6 facing the bottom 3 is 1 mm to 20 mm so as to surround the outside of the leg 7. In addition, although the thickness of a baffle plate is 2-5 mm and a material should just be a metal, stainless steel is especially preferable.

  The molded body of the panel for 32 type cathode ray tube (see FIG. 7) was cooled using the lower mold 2 having the shielding plate 5 and the current plate 6 illustrated in FIGS. This panel is a horizontally long product with an aspect ratio of 16: 9, the outer surface of the face part is substantially flat (the radius of curvature is 50000 mm), the thickness of the center part of the face part is about 12 mm, and it corresponds to the peripheral part of the face part. The wall thickness at the end of the major axis is approximately 20 mm, and the thickness at the end of the diagonal axis is approximately 24 mm.

  The shielding plate 5 was a circular plate having a diameter of 200 mm and a thickness of 5 mm with a hole 10 having a diameter of 20 mm in the center, and was installed in the center surrounded by the legs 7 20 mm below the bottom 3 of the lower mold 2. Further, the thickness of the rectifying plate is 2 mm, and the gap between the bottom 3 of the lower mold 2 and the surface of the rectifying plate 6 facing the bottom 3 of the lower mold 2 preferentially cools the long axis direction. Was 2 mm and the major axis direction was 7 mm. FIG. 3 is a gap distribution diagram between the bottom of the lower die and the surface of the rectifying plate facing the bottom of the lower die in the embodiment in which the circumferential direction of the rectifying plate 6 is the horizontal axis.

  On the other hand, the lower mold is cooled by using a conventional cooling device (not shown), the inside diameter of the cooling air blowing hole 9 is 60 mm, the flow velocity of the cooling air is about 50 m / s, and from the start of blowing air per position. The time to stop blowing was set to 18 seconds.

  Further, as a comparative example, a conventional lower mold as shown in FIG. 6 is prepared, and the lower mold of this comparative example is installed at another position of the molding apparatus to which the lower mold of the embodiment is attached, and the panel is the same Molded under conditions.

  Next, the internal temperature of the lower mold was actually measured along the major axis at the timing immediately after the panel was taken out. FIG. 4 is a temperature distribution diagram of the long axis cross section of the lower mold in the example. As shown in FIG. 4, in the example, the temperature at the center of the inner surface of the lower mold was 495 ° C. and the maximum temperature at the end of the long axis was 600 ° C., whereas in the comparative example, the temperature at the center of the bottom surface was 500 ° C. The maximum temperature at the end of the long axis was 540 ° C.

  From this result, it was confirmed that the present invention can sufficiently obtain the effect of lowering the temperature of the peripheral part without lowering the temperature of the lower mold central part.

  As described above, according to the present invention, in a manufacturing process of a glass panel for a cathode ray tube, in particular, in the manufacturing process of the glass panel for a cathode ray tube, the thickness of the peripheral portion of the face portion is significantly larger than the thickness of the central portion. When cooling the mold, it is possible to provide a lower mold for a glass panel for a cathode ray tube and a manufacturing method capable of relatively strongly cooling the peripheral portion without overcooling the central portion of the bottom portion of the lower mold.

The top view of the lower mold | type which is preferable embodiment of this invention. Sectional drawing in the AA part of FIG. FIG. 6 is a gap distribution diagram between the bottom of the lower mold and the surface of the rectifying plate facing the bottom of the lower mold in the embodiment. The major axis cross-section temperature distribution figure of the lower mold | type in an Example. Plane explanatory drawing which shows the shaping | molding flow in the shaping | molding apparatus of the glass panel for cathode ray tubes. Cross-sectional explanatory drawing of the lower mold | type for glass panel shaping | molding for cathode ray tubes of a prior art. Sectional drawing of the glass panel molding for cathode ray tubes.

Explanation of symbols

1: Glass panel molded article for cathode ray tube 2: Lower mold 3: Bottom part 4: Side wall part 5: Shielding plate 6: Rectifying plate 7: Leg 8: Mounting flange 9: Air blowing hole 10: Hole 11 in the central part of the shielding plate: Shielding Arm 12 for fixing the plate: Outlet 13: Face 14: Center 15: Peripheral 16: Turntable

Claims (5)

It has a glass filling portion for forming a cathode ray tube glass panel formed by a substantially rectangular bottom portion and side wall portions provided on the four sides of the bottom portion, and the cathode ray tube glass panel molding in the glass filling portion is disposed below the bottom portion. A lower mold for forming a cathode ray tube glass panel that is cooled by a refrigerant supplied to the center of the bottom from
A shielding plate disposed below the bottom, above the coolant blowing hole, and disposed horizontally in accordance with the horizontal center of the lower mold;
A rectifying plate that is below the bottom, is an upper end of the coolant blowing hole, and is arranged in a vertical direction outside the shielding plate;
A lower mold for forming a cathode ray tube glass panel.   2. The lower mold for molding a cathode ray tube glass panel according to claim 1, wherein the shielding plate has a hole in a central portion of the shielding plate.   The lower mold for molding a cathode ray tube glass panel according to claim 1 or 2, wherein the hole of the shielding plate is substantially circular, and the diameter of the hole is 10 mm or more and 30 mm or less.   The gap between the surface facing the bottom of the rectifying plate and the bottom of the lower mold for forming the cathode ray tube glass panel is 1 mm or more and 20 mm or less, according to any one of claims 1 to 3. The lower mold for molding a cathode ray tube glass panel as described. A molten glass is supplied to a lower mold for forming a cathode ray tube glass panel formed by a substantially rectangular bottom and side walls provided on the four sides of the bottom to mold a cathode ray tube glass panel molding, and then the lower mold In the method for manufacturing a glass panel for a cathode ray tube, the refrigerant is supplied toward the center of the bottom of the glass mold and the glass molded product filled in the lower mold is cooled.
A method for producing a glass panel for a cathode ray tube, wherein the lower mold for molding a cathode ray tube glass panel according to any one of claims 1 to 4 is used.

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