JPH08111190A - Funnel for color cathode ray tube - Google Patents

Abstract

PURPOSE: To hardly cause cracking and stagnant coating liquid trouble even if a step exists near an opening end by forming the step resulting from mold matching with a gentle curved face. CONSTITUTION: A step 17 resulting from mold matching, formed all over the side periphery near a rectangular opening end, has a gentle curved face. A funnel 13 which has the smaller inner diameter at the lower end than the inner diameter at the upper end of a bottom mold is formed by using a ring mold whose inner periphery at the lower end is chamfered into a curved shape. The funnel 13 having such a step 17 with a curved face to reduce stress concentration thereon is hardly cracked even if heat treatment is given in the following process or shock is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a rectangular opening end and has a funnel-like shape as a whole, and a step caused by a mold match over a side circumference near the opening end. The present invention relates to a funnel for a color cathode ray tube in which a portion is formed.

[0002]

2. Description of the Related Art Conventionally, when molding a funnel used for a color cathode ray tube, a molten glass is loaded into a bottom mold 10 as shown in FIG.
A method of press forming molten glass by lowering 1 is adopted. The upper end of this bottom mold 10 is
A funnel 13 having a substantially rectangular shape and having a rectangular opening end by a ring mold 12 arranged thereon.
Is formed.

When the funnel 13 is molded with such a mold, the molten glass penetrates into the joint between the bottom mold 10 and the ring mold 12 over the side circumference in the vicinity of the open end of the funnel 13, and A protrusion will be formed over the side circumference. When such a protrusion is formed, stress concentrates there, and the heat resistance and impact resistance of the funnel 13 are reduced, cracks are more likely to occur, and the shape of the protrusion increases as the funnel 13 becomes larger. However, there is a problem in that the cracks are likely to occur.

Therefore, in recent years, when molding a funnel used for a large-sized color cathode ray tube of, for example, 29 inches or more, the inner diameter of the lower end portion of the ring mold 12 is larger than the inner diameter of the upper end portion of the bottom mold 10 as shown in FIG. Is designed to be small, and a step 14 is formed at the joint.

The reason for this is that when the molten glass is press-formed by lowering the plunger 11, the step 14 makes it easier for the molten glass to flow inward. As a result, the molten glass is less likely to enter the joint between the bottom mold 10 and the ring mold 12, and it is possible to prevent the formation of protrusions along the side circumference of the funnel 13.

[0006]

However, even if the bottom mold and the ring mold are designed to have a step at the seam, a so-called mold match is made at a position corresponding to the seam of the funnel 13 as shown in FIG. Therefore, the stepped portion 15 is formed. Although there is a bent portion 16 in such a stepped portion 15, stress is also applied to the bent portion 16 even if it is not as great as the above-mentioned protruding portion, and the heat resistance and impact resistance of the funnel 13 are also increased. May decrease.

In addition, when a panel serving as an image plane of the cathode ray tube is sealed at the opening end of the funnel 13 by using frit glass and then the panel surface is coated with an antistatic film or an antireflection film, When the coating solution reaches the step portion 15 formed on the funnel 13, the coating solution easily accumulates there. When the liquid pool is solidified, cracks are generated here, and due to this, the funnel 13 is also easily cracked.

The present invention has been made in view of the above problems, and is for a color cathode ray tube in which even if there is a step near the open end, cracks are less likely to occur from this step, and moreover, the coating liquid is less likely to pool. The purpose is to provide a funnel.

[0009]

A funnel for a color cathode ray tube according to the present invention is provided with a rectangular opening end portion and has a funnel shape as a whole, and is provided around a side circumference near the opening end portion. In a funnel for a color cathode ray tube in which a step due to a mold match is formed, the step has a gently curved surface.

[0010]

In the funnel for a color cathode ray tube of the present invention, a step portion due to the mold match is formed over the side circumference near the opening end, but this step portion has a gentle curved surface. Since there is no bent portion, concentration of stress on this portion is small, and it is possible to prevent deterioration of heat resistance and impact resistance of the funnel.

Moreover, even when the coating liquid is applied to the panel surface after sealing the open end of the funnel of the present invention with the panel, the coating liquid is less likely to accumulate on the stepped portion, so that the occurrence of cracks can be prevented. It will be possible.

[0012]

EXAMPLES The funnel for a color cathode ray tube of the present invention will be described in detail below with reference to examples.

FIG. 1 is an enlarged sectional view of an essential part showing a funnel 13 for a color cathode ray tube according to the present invention. In the figure, a step portion 17 caused by a mold match is formed over the side circumference near the rectangular opening end portion, and the step portion 17 has a gently curved surface.

The funnel 13 has an inner diameter at the lower end,
It can be obtained by using a ring mold whose inner diameter is smaller than the inner diameter of the upper end of the bottom mold and whose inner periphery is chamfered in a curved shape.

According to such a funnel 13, since the step portion 17 has the curved surface, the stress concentration on this portion is small, and even if a heat treatment is applied or an impact is applied in a later step, Hard to crack.

When the open end of the funnel 13 is sealed to the panel using frit glass and then the panel surface is coated with an antistatic film or an antireflection film,
Even if the coating solution reaches the step portion 17 of the funnel 13, the coating solution flows on the curved surface, so that the coating solution does not easily accumulate there.

[0017]

As described above, according to the funnel for a color cathode ray tube of the present invention, stress is less likely to be concentrated on the step portion due to the mold match, and moreover, after sealing this to the panel, the coating liquid is applied to the panel surface, Even if the coating solution reaches this step, it is difficult for the coating solution to accumulate, so that it is possible to prevent the occurrence of cracks.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing a funnel of the present invention.

FIG. 2 is a cross-sectional explanatory view showing a conventional funnel molding method.

FIG. 3 is a cross-sectional view of a main part showing the vicinity of an open end of a funnel during conventional press molding.

FIG. 4 is an enlarged sectional view of an essential part showing a conventional funnel.

[Explanation of symbols]

 10 Bottom Mold 11 Plunger 12 Ring Mold 13 Funnel 15, 17 Steps

Claims (1)

[Claims] 1. A rectangular opening end is provided, which has a funnel-like shape as a whole, and a step portion due to a mold match is formed over a side circumference near the opening end. A funnel for a color cathode ray tube, wherein the step portion has a gently curved surface.