JP2000030612A - Manufacturing method of explosion-proof cathode ray tube - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a method of manufacturing an explosion-proof cathode ray tube using a shrink fitting method, overheating that occurs near an electrode during energization heating of an explosion-proof band is prevented so that quality and reliability do not deteriorate. The purpose is to. SOLUTION: Electrodes 8 and 9 are pressed into contact with a plated ring-shaped explosion-proof band 7 and energized and heated, and the side wall of the panel is inserted inside the explosion-proof band expanded by this heating, and the explosion-proof band is cooled and shrunk. Thus, in the method of manufacturing an explosion-proof cathode ray tube in which the side wall of the panel is tightened, a gas is blown near the contact portion with the electrode when the explosion-proof band is heated to be cooled.

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 an explosion-proof cathode ray tube in which an explosion-proof band is mounted by an explosion-proof treatment of a shrink-fit type, and more particularly to a method for manufacturing an explosion-proof cathode-ray tube with an improved method for heating the explosion-proof band.

[0002]

2. Description of the Related Art Generally, a cathode ray tube is, as shown in FIG.
A vacuum envelope comprising a substantially rectangular glass panel 3 having a side wall 2 provided around the effective portion 1 and a funnel-shaped glass funnel 5 having a cylindrical neck 4 at one end. . In the color picture tube, the panel 3 and the funnel 4 are joined by a frit glass 6.

A vacuum envelope made of such a glass is
Due to the atmospheric pressure load, the central portion of the effective portion of the panel is pushed into the inside of the envelope, and a deformation stress is generated that is pushed outward from the side wall portion to the large diameter portion of the funnel. for that reason,
Due to an external impact or the like, an implosion may occur starting from a fine scratch on the surface of the envelope. In order to prevent this implosion, many cathode ray tubes are subjected to an explosion-proof treatment in which the outer periphery of the side wall 2 of the panel 3 is fastened by an explosion-proof band 7.

[0004] There are various types of explosion-proof treatment, one of which is a shrink fitting method. In this shrink fitting method, both ends of a band-shaped explosion-proof band made of a mild steel plate plated in advance are welded to form an inner periphery shorter than the outer peripheral length of a side wall portion of a panel constituting a vacuum envelope of a cathode ray tube. The explosion-proof band should be
After heating to about 0 ° C. to expand, the side wall of the panel of the cathode ray tube is inserted inside the expanded annular explosion-proof band, and the panel side wall is tightened by cooling and shrinking the annular explosion-proof band. It is carried out.

[0005] Generally, the explosion-proof band used in the shrink-fitting explosion-proof treatment is plated.
An explosion-proof band mainly subjected to galvanization and an explosion-proof band subjected to hot-dip plating of an alloy of aluminum and zinc are used.

On the other hand, the heating for expanding the annular explosion-proof band is as follows: (a) a method in which a heating burner is arranged inside the explosion-proof band to heat it; and (b) a high-frequency induction heating coil is arranged around the explosion-proof band. (C) There is a method in which the electrodes are pressed against the explosion-proof band and the electrodes are heated.

However, the heating method using the burner (a) has problems such as uniformity of heating and environmental pollution by exhaust gas. In addition, the high frequency induction heating method (b) has problems in that the heating cost is high and a relatively large installation space is required, in addition to the problems of uniformity of heating, accuracy of attaching the explosion-proof band to the cathode ray tube. .

[0008] On the other hand, (c) the energization heating method is as follows:
As shown in FIGS. 7 and 8, the center of the opposite side of the ring-shaped explosion-proof band 7 is gripped by a pair of electrodes 8 and 9, respectively, and the heating is performed by applying current through these electrodes 8 and 9. Therefore, in this method, since the heating is performed directly by the current flowing through the explosion-proof band 6, the heating efficiency can be improved in principle, the uniform heating can be performed, and the heating time can be shortened.
It can be said that the heating method is superior to the above (a) and (b).

However, in practice, the current density near the electrodes 8 and 9 indicated by the broken line 10 in FIG. 9 becomes higher than the other parts, and the vicinity of the electrodes 8 and 9 is overheated. Therefore, for example, in an explosion-proof band that has been subjected to galvanization, the diffusion of iron components into the zinc layer occurs in the overheated portion, and in an explosion-proof band that has been subjected to hot-dip plating of an alloy of aluminum and zinc, the molten deposition of aluminum occurs. In addition to the deterioration of the appearance of the explosion-proof band, there is a problem that the rust prevention effect is deteriorated and rust is generated, and quality and reliability are deteriorated, such as a short circuit of a display device circuit board due to the rust falling off. .

[0010]

As described above, in one type of explosion-proof treatment of a cathode ray tube, a ring-shaped explosion-proof band is heated and expanded, and a side wall portion of a panel is inserted inside the band. There is a method called shrink fitting in which the side wall of the panel is tightened by cooling shrinkage of the panel.

The explosion-proof band can be heated by disposing a heating burner inside the explosion-proof band, heating by disposing a high-frequency induction heating coil around the explosion-proof band, or by bringing an electrode into contact with the explosion-proof band. There are methods such as heating by energization, among these,
In principle, it is possible to improve the heating efficiency, uniform heating, and shorten the heating time, and it can be said that this is a superior heating method compared to other methods.

However, in practice, the current density near the electrode that is in pressure contact with the explosion-proof band becomes higher than in other parts, and the vicinity of the electrode is overheated. In the explosion-proof band where the iron component is diffused into the zinc layer and the hot-dip plating of the alloy of aluminum and zinc is performed, the molten deposition of aluminum occurs.
As a result, there is a problem that the appearance and the rust prevention effect of the explosion-proof band are deteriorated and rust is generated, and the rust is dropped, resulting in a shortage of the circuit board of the display device and a decrease in quality and reliability.

As a measure for preventing overheating in the vicinity of the electrodes, it is conceivable to set the temperature of the explosion-proof band to a lower temperature by controlling the heating power. However, when the temperature of the explosion-proof band is lowered, when the cathode ray tube is inserted inside the band, This makes it easy for flaws and plating to adhere to the side wall of the panel. Further, since the cathode ray tube is attached to the display device, the positional accuracy of the lug plate 11 (see FIG. 4) provided on the explosion-proof band tends to be inaccurate.

As another preventive measure, a method of enlarging the contact area of the electrode can be considered. However, the surface of the explosion-proof band has irregularities, and depending on the type, there is a step or a groove. Then, poor contact is likely to occur, and heating stability is impaired.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and in a method of manufacturing an explosion-proof cathode ray tube by shrink fitting, it is possible to prevent overheating occurring in the vicinity of an electrode when energizing and heating an explosion-proof band. Therefore, it is an object of the present invention to prevent deterioration in quality and reliability such as generation of rust due to deterioration of the appearance of the explosion-proof band and deterioration of the rust prevention effect.

[0016]

Means for Solving the Problems (1) An electrode is pressed into contact with a plated ring-shaped explosion-proof band and heated by energization, and the side wall of the panel is inserted inside the explosion-proof band expanded by this heating, thereby explosion-proofing. In a method of manufacturing an explosion-proof cathode ray tube in which a side wall of a panel is fastened by cooling and shrinking of a band, a gas is blown near a contact portion with an electrode when the explosion-proof band is heated to be cooled.

(2) In the method for manufacturing an explosion-proof cathode ray tube of (1), gas is blown to at least one of the inner and outer surfaces of the explosion-proof band.

(3) In the method for manufacturing an explosion-proof cathode ray tube of (2), gas is blown to both the inner and outer surfaces of the explosion-proof band.

(4) In the method for manufacturing an explosion-proof cathode ray tube according to any one of (1) to (3), the heating temperature of the entire explosion-proof band is made uniform by adjusting the flow rate of gas blown in the vicinity of the contact portion with the electrode. I tried to.

(5) In the method for manufacturing an explosion-proof cathode ray tube according to any one of (1) to (4), gas is blown from a nozzle provided separately and independently from the electrode.

(6) In the method for manufacturing an explosion-proof cathode ray tube according to any one of (1) to (4), gas is blown from a nozzle provided integrally with the electrode.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, one side of a strip-shaped mild steel plate 20 which has been subjected to galvanizing or hot-dip plating of an alloy of aluminum and zinc is folded by roll processing to form a folded portion 21. Next, as shown in FIG. 2, the belt-shaped mild steel plate 20 on which the folded portion 21 is formed is bent into an annular shape having an inner peripheral length shorter than the outer peripheral length of the side wall portion of the panel of the color picture tube by a predetermined amount. The two ends are butted and welded to form a rectangular annular explosion-proof band 7. Further, a lug plate 11 is welded to the corner of the explosion-proof band 7.

Next, the center of the opposite side of the explosion-proof band 7 is gripped by a pair of electrodes (see FIG. 7).
Electric current is heated through the electrodes pressed by the grip. At this time, in this embodiment, as shown in FIG. 3, a pair of nozzles 23 are arranged on both sides of each of the electrodes 8 and 9,
For example, air is blown from the nozzles 23 to the inner and outer surfaces of the explosion-proof band 7 in the vicinity of the electrodes 8 and 9 while cooling the air.
The explosion-proof band 7 is heated to about 500 ° C. to expand.

On the other hand, as shown in FIG. 4, an explosion-proof tape 24 is wound around the outer periphery of the side wall 2 of the panel 3 of the color picture tube.
Then, as shown in FIG. 5, the side wall portion 2 of the panel 3 around which the explosion-proof tape 24 is wound is inserted into the inside of the explosion-proof band 7 that has been heated and expanded, and the side wall portion of the panel 3 is cooled and contracted. Tighten 2.

As described above, when the electrodes 8 and 9 are pressed against the ring-shaped explosion-proof band 7 and energized and heated, air is blown on both surfaces in the vicinity of the electrodes 8 and 9 to cause the electrodes 8 and 9 to blow.
9 can be suppressed. As a result, in an explosion-proof band conventionally coated with zinc, the iron component diffuses into the zinc layer due to overheating, and in an explosion-proof band coated with an alloy of aluminum and zinc, aluminum is molten and deposited. Therefore, it is possible to prevent the appearance of the explosion-proof band from deteriorating, and prevent rust from being generated due to a reduction in rust-preventing effect.

Moreover, even if the air is blown, since the part to be cooled is localized, it does not affect the thermal expansion of the entire explosion-proof band 7 at all. In addition, by adjusting the flow rate of the blowing air, the entire explosion-proof band 7 can be uniformly heated.

In the above-described embodiment, air is blown to the explosion-proof band to suppress overheating, but a gas other than air, such as nitrogen, may be blown.

In the above-described embodiment, air is blown to both sides of the explosion-proof band. However, the same effect can be obtained by blowing air to only one of the inner and outer surfaces of the explosion-proof band. can get.

In the above embodiment, air is blown by providing a nozzle separately from the electrode. However, even if the nozzle is provided integrally with the electrode, overheating in the vicinity of the electrode can be suppressed.

In the above embodiment, the color picture tube has been described. However, the present invention can be applied to a cathode ray tube other than the color picture tube.

[0032]

As described above, when the electrode is pressed into contact with the plated ring-shaped explosion-proof band and heated by energization, the gas is blown into the vicinity of the contact portion with the electrode and cooled, thereby overheating near the electrode. Thus, it is possible to manufacture a stable explosion-proof cathode ray tube which does not impair the quality and reliability of the explosion-proof band, preventing deterioration of the plating of the explosion-proof band caused by overheating.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the folding of a belt-shaped mild steel plate in a manufacturing process of an explosion-proof color picture tube according to an embodiment of the present invention.

FIG. 2 is a view for explaining formation of an annular metal band in a process of manufacturing the explosion-proof color picture tube.

FIG. 3 is a view for explaining electric heating of an annular metal band in a process of manufacturing the explosion-proof color picture tube.

FIG. 4 is a diagram for explaining winding of an explosion-proof tape in a process of manufacturing the explosion-proof color picture tube.

FIG. 5 is a view for explaining attachment of an annular metal band in a process of manufacturing the explosion-proof color picture tube.

FIG. 6 is a diagram showing a configuration of an explosion-proof color picture tube.

FIG. 7 is a view for explaining electric heating of an annular metal band in a process of manufacturing a conventional explosion-proof color picture tube.

FIG. 8 is a view for explaining electric heating of an annular metal band in a process of manufacturing a conventional explosion-proof color picture tube.

FIG. 9 is a view for explaining a problem of current heating of an annular metal band in a process of manufacturing a conventional explosion-proof color picture tube.

[Explanation of symbols]

 2 ... side wall 3 ... panel 7 ... explosion-proof band 8 ... electrode 9 ... electrode 23 ... nozzle

Claims (6)

[Claims] An electrode is pressed into contact with a plated ring-shaped explosion-proof band, and the electrode is heated by current application. A side wall portion of a panel is inserted inside the explosion-proof band expanded by the heating, and the explosion-proof band is cooled and shrunk by cooling. A method for manufacturing an explosion-proof cathode ray tube for fastening an explosion-proof cathode ray tube, wherein a gas is blown near a contact portion with the electrode when the explosion-proof band is heated to cool the explosion-proof cathode ray tube. 2. The method for manufacturing an explosion-proof cathode ray tube according to claim 1, wherein gas is blown onto at least one of the inner and outer surfaces of the explosion-proof band. 3. The method for manufacturing an explosion-proof cathode ray tube according to claim 2, wherein gas is blown onto both the inner and outer surfaces of the explosion-proof band. 4. The explosion-proof cathode wire according to claim 1, wherein the heating temperature of the entire explosion-proof band is made uniform by adjusting the flow rate of gas blown in the vicinity of the contact portion with the electrode. Pipe manufacturing method. 5. The method for producing an explosion-proof cathode ray tube according to claim 1, wherein a gas is blown from a nozzle provided separately and independently from the electrode. 6. The method for producing an explosion-proof cathode ray tube according to claim 1, wherein a gas is blown from a nozzle provided integrally with the electrode.