JP2001328830A - Method for producing glass panel for cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a glass panel for a cathode ray tube capable of making the thickness of side wall thin and lightening the cathode ray tube. SOLUTION: This method for producing a glass panel is characterized in that the method has a first process for supplying a molten glass gob to a molding mold, press molding the gob into a glass molding provided with a face part on which an image is projected and side wall parts extended approximately in the vertical direction around the face part and cooling and solidifying the glass molding in the molding mold, a second process for taking out the glass molding from the molding mold, quenching the glass molding and forming a compression stress layer on the surface to temper the glass molding, a third process for fusing a stud pin to the glass molding and a fourth process for annealing the glass molding and the side wall parts are heated to an annealing point or higher than it before the glass molding is quenched in the second process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a glass panel for a cathode ray tube used for a television or a monitor.

[0002]

2. Description of the Related Art In recent years, with the flattening of display screens of televisions and monitor devices, a glass panel for a cathode ray tube has been developed to prevent the breakdown of the cathode ray tube by forming a compressive stress layer on the surface and strengthening the layer. Used.

As shown in FIG. 3, a glass panel 1 for a cathode ray tube has a structure comprising a substantially rectangular face portion 2 on which an image is projected and a side wall portion 3 extending substantially vertically from the entire periphery thereof. When a funnel-shaped funnel (not shown) is frit-sealed to the seal edge 3a of the side wall portion 3 of the tube glass panel 1 to produce a cathode ray tube, the maximum tensile strength caused by the vacuum inside is produced. Stress is generated in the region of the peripheral portion 2 a of the face portion 2 and the outer surface of the side wall portion 3. Therefore, in order to maintain the required pressure resistance, the glass panel 1 for a cathode ray tube is formed with a compressive stress layer 1a so that the compressive stress value in the peripheral portion 2a region of the face portion 2 becomes large.

The glass panel 1 for a cathode ray tube reinforced as described above is formed by press-molding a gob of molten glass supplied into a molding die into a glass molded product having a face portion 2 and a side wall portion 3. After cooling and solidifying in the mold, and taking out the glass molded product from the molding die, the glass molded product having a temperature higher than the annealing point is rapidly cooled to a temperature lower than the strain point to form a compressive stress layer 1a on the surface. It is obtained by strengthening by forming and then slowly cooling the glass molded article to room temperature.

[0005]

However, in the glass panel 1 for a cathode ray tube reinforced by the conventional method, since the thin side wall portion 3 has a small heat capacity, the heat radiation speed is higher than that of the thick face portion 2. At the time of rapid cooling, the temperature has already been near the strain point or lower than the strain point, and the compressive stress value of the formed compressive stress layer 1 a becomes smaller than that of the face portion 2. Therefore, when a cathode ray tube is manufactured, it is necessary to increase the thickness of the side wall portion 3 with respect to the maximum tensile stress generated due to the inside being vacuum.
There is a problem that the weight of the glass panel 1 for a cathode ray tube cannot be reduced.

An object of the present invention is to provide a method of manufacturing a glass panel for a cathode ray tube, which solves the above-mentioned conventional problems.

[0007]

According to the method of manufacturing a glass panel for a cathode ray tube of the present invention, a gob of molten glass is supplied into a molding die, and the gob is substantially vertically extended around a face portion on which an image is projected and the periphery thereof. The first step of press-molding into a glass molded product having a side wall extending to the surface and cooling and solidifying in a molding die, and after taking out the glass molded product from the molding die, quenching the glass molded product and quenching the surface A second step of forming and strengthening a compressive stress layer on the glass, a third step of welding stud pins to the glass molded article, and a fourth step of gradually cooling the glass molded article; The method is characterized in that the side wall is heated to a temperature equal to or higher than the annealing point before the molded product is rapidly cooled.

According to the present invention, in order to make the compressive stress value of the compressive stress layer formed on the thin side wall portion where the heat radiation rate of the glass panel for a cathode ray tube is fast equal to that of the thick face portion, glass molding is performed in the second step. It is important to heat the side wall portion to a temperature equal to or higher than the annealing point of the glass before the article is rapidly cooled, and it is preferable to heat the side wall portion so as to be higher than the thick face portion.

As a method of heating the side wall portion of the glass panel for a cathode ray tube to a temperature not lower than the annealing point, a heating element heated by energization, a burner flame, a ceramic or heat-resistant metal having high radiation efficiency of far-infrared rays which glass absorbs well. This can be achieved by heating a plate or the like with a heating element or a burner flame or the like so as to approach them. In order to enhance the thermal efficiency, it is preferable to provide a cover for covering the heating portion such as the heating element and keeping the temperature.

[0010]

According to the method of manufacturing a glass panel for a cathode ray tube of the present invention, in the second step, the side wall is heated to a temperature equal to or higher than the annealing point before the glass molded article is rapidly cooled. The compressive stress value of the layer can be made substantially equal to that of the compressive stress layer formed on the thick face portion.

[0011]

FIG. 1 shows the transition of the temperature of the face 2 and the side wall 3 in the method of manufacturing a glass panel for a cathode ray tube according to the present invention. FIG. 2 is a cross-sectional view of a glass panel for a cathode ray tube manufactured according to the present invention, in which 1 is a glass panel for a cathode ray tube, 1a is a compressive stress layer, and 2 is a substantially rectangular face on which an image is projected. Portion, 3 is a side wall portion extending from the face portion 2 to form a side wall, 3a is a seal edge, t is an average thickness of the side wall portion 3, and R is a diagonal axis direction of the outer surface of the face portion 2. The average radius of curvature is shown, and the same parts as those in FIG. 3 are given the same reference numerals.

According to the manufacturing method of the present invention, the average thickness t of the side wall portion 3 as shown in FIG. 2 is as thin as 11.0 mm, and the average radius of curvature R of the outer surface of the face portion 2 in the diagonal axis direction is about 1000.
A case where the glass panel 1 for a cathode ray tube having a flat face portion of 00 mm will be described.

First, as shown in FIG. 1, in a first step, a gob of molten glass at about 1000 ° C. is supplied into a molding die.
The gob is press-molded into a glass molded product comprising a substantially rectangular face portion 2 on which an image is projected and a side wall portion 3 extending substantially vertically around the face portion, and is cooled and solidified in a molding die. Thereafter, in the second step, the glass molded product is taken out of the molding die and conveyed in about 30 seconds, and the side wall 3 is gradually cooled to 51 from the side of the seal edge 3a by a heating device (not shown).
Heat to 550 ° C. above 4 ° C. for 120 seconds. At this point, the temperature of the face portion 2 is 495 ° C., which is 55 ° C. lower than that of the side wall portion 3. By blowing cooling air at a pressure of 1.0 kg / cm ² onto the side wall portion 3 of the glass molded product at such a temperature for 30 seconds, it is rapidly cooled to a strain point of 473 ° C. or less and compressive stress is applied to the glass surface of the side wall portion 3. It is strengthened by forming the layer 1a. In the third step, the stud pins are fused to the glass molded product, and the glass molded product is finally cooled to around 430 ° C. In the fourth step, the glass molded product is raised and held at a maximum temperature of about 485 ° C. in an annealing furnace,
Thereafter, the glass panel 1 for a cathode ray tube in which the side wall portion 3 is strengthened is obtained by gradually cooling over time to cool to room temperature. After heating the stud pins and the like in the third step as they are without heating the side wall part 3 and transporting them, the fourth step is then performed in a slow cooling furnace controlled at a maximum temperature of 485 ° C. to be gradually cooled. .

The evaluation of the reinforced glass panel 1 for a cathode ray tube was performed by dropping an iron ball having a weight of 20 g on the seal edge portion 3a of the side wall portion 3 and measuring the height at which cracks were generated.

[0015]

[Table 1]

As is clear from Table 1, the glass panel 1 for a cathode ray tube manufactured according to the present invention has a side wall 3
When an iron ball weighing 20 g is dropped on the seal edge portion 3a, the height at which cracks occur is 70 mm on average, almost three times stronger than that of a conventional glass panel for a cathode ray tube.
By reducing the average thickness t of the side wall portion 3 to 11.0 mm, the weight is reduced to 19.7 kg, and the average radius of curvature R in the diagonal axis direction of the outer surface with little distortion in the projected image is 100,000 mm. Was achieved.

On the other hand, the glass panel for a cathode ray tube of the comparative example has a crack generation height of 2 when an iron ball is dropped.
6 mm, the average thickness t of the side wall 3 is 13.0 mm, and the weight is 20.3 kg.

[0018]

According to the present invention, the average thickness of the side wall of the glass panel for a cathode ray tube having a flat face can be reduced to about 85% of the conventional panel, and the weight can be reduced by about 3%. It has a practically excellent effect.

[Brief description of the drawings]

FIG. 1 is a diagram showing a temperature change of a face portion and a side wall portion in the present invention.

FIG. 2 is a cross-sectional view of a glass panel for a cathode ray tube manufactured according to the present invention.

FIG. 3 is a sectional view of a conventional glass panel for a cathode ray tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass panel for cathode ray tubes 1a Compressive stress layer 2 Face part 2a Peripheral part 3 Side wall part 3a Seal edge

Claims (1)

[Claims] 1. A gob of molten glass is supplied into a molding die, and the gob is press-molded into a glass molded article having a face on which an image is projected and a side wall extending substantially vertically around the face. A first step of cooling and solidifying in a molding die, a second step of taking out the glass molded product from the molding die, rapidly cooling the glass molded product to form a compressive stress layer on the surface, and strengthening the glass; A third step of welding a stud pin to the molded article, and a fourth step of gradually cooling the glass molded article, and before the glass molded article is rapidly cooled in the second step, the side wall portion is gradually cooled to a temperature equal to or higher than the annealing point. A method for producing a glass panel for a cathode ray tube, comprising heating.