JP2000351638A - Apparatus for cooling bottom mold for forming glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple and inexpensive apparatus for cooling a bottom mold to improve the non-uniform temperature distribution of a bottom mold to be used for the press-forming of a glass article. SOLUTION: This cooling apparatus cools the bottom mold 2 for the press- forming of a glass article 1 by blowing cooling air 6 from under. It is provided with a cooling air straightening pipe 4 formed under the bottom mold fixed on a table of a press-forming apparatus and the pipe has a blowing port having nearly rectangular cross-section on the top of the pipe. The temperature distribution of the bottom mold is uniformized by converging the cooling air flow on the hot part of the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device for a bottom die used for press-forming glass articles, and more particularly to a cooling device for a bottom die for press-forming a glass panel for a cathode ray tube or the like, which requires high dimensional accuracy. Things.

[0002]

2. Description of the Related Art When manufacturing a glass article by press-molding a high-temperature molten glass ingot, the glass article is cooled in a short time as much as possible and can be taken out from a press forming apparatus. The glass article is cooled by contacting it with a mold having a relatively low temperature, mainly a bottom mold, and cooling it, and by blowing cooling air directly onto the glass surface.

[0003] As shown in FIG. 3, a glass article 1 such as a glass panel for a cathode ray tube is generally supplied with a high-temperature molten glass lump to a bottom mold 2, press-formed, cooled, solidified, and then cooled. Take out and manufacture. Usually, a plurality of the bottom dies 2 are mounted and fixed at predetermined intervals on a table 3 of a press molding apparatus. In order to cool the bottom dies, conventionally, a cooling air rectification having a circular outlet is conventionally used. A cylinder 4 is provided on the table 3 below the bottom mold so as to face each bottom mold. Cooling air 5 is supplied to the cooling air rectification cylinder 4 by a blower or the like (not shown), and is substantially uniformly distributed in each direction from the upper outlet of the cooling air rectification cylinder 4 along the lower surface of the bottom mold 2. The cooling air 6 flows and cools the bottom mold.

[0004] The bottom mold receives heat from hot glass, while
Since it is cooled by the cooling air 6, it has a temperature history of the bottom mold according to a series of cycles in which a high-temperature glass block is supplied onto the bottom mold, and after cooling, the cooled glass article is taken out from the bottom mold. Also, when the glass article has a substantially uniform thickness and a substantially rectangular box shape like a glass panel for a cathode ray tube over the temperature hysteresis cycle, the bottom mold lower surface has a temperature distribution as shown in FIG. Is generated. That is, the temperature is low as indicated by L in the central portion where the cooling air is directly hit and the cooling air amount is maximum, and the peripheral portion where the heat radiation area is large, and the intermediate portion is relatively as indicated by H. Temperature rises. Further, the temperature of the intermediate portion in the major axis X direction, which has a large heat receiving area from the glass article, is higher than that of the intermediate portion in the minor axis Y direction.

[0005] When the non-uniformity of the temperature distribution on the lower surface of the bottom die becomes large, the temperature distribution on the glass molding surface of the bottom die becomes substantially non-uniform as well, and a glass panel for a cathode ray tube or the like which requires precise dimensional accuracy. In the case of (1), since the cooling rate of the glass is non-uniform in a portion in contact with the bottom mold of the glass panel, a curvature deviation of the glass panel occurs partially. That is, partial irregularities are generated with respect to a predetermined curvature of the glass panel image surface, and it is difficult to guarantee strict dimensional accuracy of the image area over the entire surface of the glass panel inner surface. In such a case, there is a quality problem such as partial unevenness distorting the surface reflected light. In the case of a so-called flat glass panel having a large curvature on the outer surface of the image area of the glass panel, the unevenness is further emphasized, which is more problematic.

As described above, the area where the image of the glass panel is projected requires particularly strict control of the molding dimension.
Since the non-uniform temperature distribution on the bottom glass molding surface makes it difficult to control the curvature dimension of the glass panel and causes a problem, a material having good thermal conductivity as proposed in Japanese Patent Application Laid-Open No. 8-165125 is used. Attempts have been made to make the temperature distribution as uniform as possible by embedding in the temperature area.

[0007]

However, performing such processing on each bottom mold is complicated, expensive, and requires complicated processing, so that the processing accuracy of each mold is not uniform. Easy to do. On the other hand, as described above, conventionally, as the bottom-type cooling air flow regulating cylinder, a cooling air flow regulating cylinder having an upper outlet having a circular horizontal sectional shape as shown in FIG. 4 has been used. For this reason, as shown in FIG. 6, the cooling air of the bottom die flows almost evenly in the entire horizontal direction on the bottom surface of the bottom die, and the long axis X which is a particularly high temperature portion in the temperature distribution shown in FIG. It was unsuitable for focusing cooling in the middle part of the direction.

In the case of a bottom type for a horizontally long type glass panel having an aspect ratio of 16: 9, the length of the bottom type in the major axis X direction is also increased in accordance with the shape of the glass panel. Since the amount of heat received from the glass panel also tends to be further deviated in the direction of the long axis X, as a result, the non-uniformity of the temperature distribution of the bottom die increases, and the conventional bottom-type cooling device having a cooling air rectifying cylinder having a circular outlet. In this case, it is increasingly difficult to correct the uneven temperature distribution of the bottom mold, and there is a disadvantage that the quality and the productivity of the glass panel are hindered.

Accordingly, an object of the present invention is to provide a simple and inexpensive bottom mold cooling device in order to improve a non-uniform temperature distribution generated in a bottom mold used for press molding of a glass article. An object of the present invention is to suppress the difficulty in controlling the molding dimension of a glass article, which is a problem due to the non-uniform temperature distribution, and to improve the quality and productivity of the glass article.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is a cooling apparatus for cooling a bottom mold for press-molding a glass article by blowing cooling air from below. The cooling device is provided with a cooling air straightening tube provided below a bottom die fixed and mounted on a table of the press forming device, and the cooling air straightening tube has an upwardly extending outlet having a substantially rectangular cross section. Provided is a cooling device for a bottom mold for glass molding, characterized by having

It is preferable that the length of the long-axis side of the outlet of the cooling air straightening cylinder is at least twice as long as the length of the short-axis side.

[0012] Furthermore, a bottom die for forming a substantially rectangular glass panel for a cathode ray tube, wherein a long axis direction of an outlet of the cooling air rectification tube is orthogonal to a long axis direction of the bottom die. Provided is a cooling device for a bottom mold for forming glass.

[0013]

According to the present invention, the use of a bottom-type cooling device having a cooling air rectifying cylinder in which the horizontal cross-sectional shape of the upper outlet is substantially rectangular makes it possible to increase the temperature in the horizontal direction of the bottom surface of the bottom die, especially in the axial direction where the temperature tends to increase. As a result, more cooling air can be supplied, and the uneven temperature distribution of the bottom mold can be easily improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cooling device according to the present invention will be described below with reference to FIGS. The cooling air rectification cylinder used in the cooling device of the present invention has a substantially rectangular upper outlet having a major axis side dimension of 110 mm and a minor axis side dimension of 10 mm in a horizontal cross section. The diagonal effective diameter is 59
A glass panel for a cathode ray tube having a cm (corresponding to 25 inches) and an aspect ratio of 4: 3 was press-formed. The temperature of the maximum temperature portion in the long axis direction on the lower surface of the bottom mold is about 15 times less than that of a cooling device conventionally used for forming the glass panel, which has a circular air outlet having a diameter of 40 mm. ° C and the maximum temperature difference across the bottom of the bottom mold is 30
° C. As a result, the partial curvature deviation of the glass panel image display surface generated on the glass forming surface corresponding to the vicinity of the highest temperature portion of the bottom surface of the bottom mold can be suppressed to about し て as compared with the related art, and the quality can be improved. Was.

In another embodiment, the cooling air straightening cylinder used in the cooling device of the present invention has a substantially rectangular upper outlet having a horizontal section having a major axis side dimension of 115 mm and a minor axis side dimension of 25 mm. Are arranged so that the long axis of the cooling air flow control cylinder and the long axis of the bottom mold are orthogonal to each other, and the diagonal effective diameter dimension is 86
A glass panel for a cathode ray tube having a cm (corresponding to 36 inches) and an aspect ratio of 16: 9 was press-formed. The cooling device conventionally used for forming the glass panel has a diameter of 60 mm.
As compared with the case of the cooling air rectifying cylinder having the circular air outlet dimensions, the temperature of the maximum temperature portion in the long axis direction on the bottom surface of the bottom mold is reduced by about 15 ° C., and the maximum temperature difference on the entire bottom surface of the bottom mold is reduced by 3 °
The temperature could be kept within 5 ° C. As a result, the partial curvature deviation of the glass panel image display surface generated on the glass forming surface corresponding to the vicinity of the highest temperature portion of the bottom surface of the bottom mold can be suppressed to about 比較 as compared with the related art, and the quality is improved. .

In the horizontal cross section of the upper outlet of the cooling air straightening cylinder, there is a bottom-type high-temperature portion in which the length of the substantially rectangular major axis side is at least twice the length of the minor axis side. This is preferable because more cooling air can be supplied to the major axis direction.

According to the present invention, in addition to the glass panel for a cathode ray tube shown in the above embodiment, depending on the shape and thickness distribution of the glass article, the lower surface of the press-forming bottom die may be oriented in either the X axis or the Y axis. It can be used to cool the bottom mold of any glass article that produces particularly hot parts. Further, in the above embodiment, the long axis of the cooling air rectifying cylinder and the long axis of the bottom mold are disposed so as to be orthogonal to each other. If this occurs, the cooling air straightening cylinder is disposed so that its short axis and the short axis of the bottom die are in the same direction.

In the above embodiment of the present invention, the shape of the outlet of the cooling air straightening cylinder is a substantially rectangular rectangle. However, in the present specification, a substantially rectangular shape is, for example, a substantially hexagonal shape or a substantially octagonal shape. The shape may include at least a major axis direction and a minor axis direction. Further, a structure may be adopted in which a partition plate or the like is provided inside the substantially rectangular outlet to further finely adjust the flow of the cooling air.

[0019]

As described above, according to the cooling apparatus for a bottom mold for glass forming of the present invention, the bottom mold, particularly the long axis, can be used for press forming of a glass panel for a cathode ray tube having a substantially rectangular shape. It has an excellent effect that the uneven temperature distribution generated in the direction can be greatly improved. As a result, since the dimensional accuracy of the glass article can be strictly controlled, the occurrence of dimensional defects or appearance defects is suppressed, and the productivity can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a cooling device of a bottom mold for molding glass articles according to an embodiment of the present invention.

FIG. 2 is a perspective view of a cooling air rectifying cylinder constituting the cooling device according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional cooling device for a glass article forming bottom mold.

FIG. 4 is a perspective view of a cooling air rectifying cylinder constituting a conventional cooling device.

FIG. 5 is an explanatory diagram showing a temperature distribution on a lower surface of a bottom mold by a conventional cooling device.

FIG. 6 is an explanatory view showing cooling air flowing along a bottom surface of a bottom mold by a conventional cooling device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass article (glass panel for cathode ray tubes) 2 Bottom type 3 Table 4 Cooling air rectification cylinder 5 Cooling air 6 Cooling air on the bottom surface of bottom type

Claims (3)

[Claims] 1. A cooling device for cooling a press-molding bottom die for glass articles by blowing cooling air from below, wherein the cooling device is provided below a bottom die placed and fixed on a table of the press-forming device. A cooling device for a bottom mold for glass forming, comprising: a cooling air straightening tube provided, wherein the cooling air straightening tube has an outlet having a substantially rectangular cross section at an upper portion thereof. 2. The cooling apparatus according to claim 1, wherein the length of the blow-out port of the cooling air flow straightening tube is at least twice as long as the length of the short-axis side. 3. A bottom mold for forming a substantially rectangular glass panel for a cathode ray tube, wherein a long axis direction of an outlet of the cooling air rectifying cylinder is orthogonal to a long axis direction of the bottom mold. The cooling device for a bottom mold for glass forming according to claim 2, wherein the cooling device is provided.