JPH06349409A - Manufacture of cathode-ray tube and metal band for implosion prevention - Google Patents

Abstract

PURPOSE:To recover a good panel from a failed, cathode-ray tube. CONSTITUTION:In the implosion prevention process before heat evacuation, a metal tape 20 is attached to eliminate or reduce a step of protrusion (D) occurring on a mold match line (L) in each corner portion of a panel portion 1. A heat-resistant, heat insulating tape 7 is then attached on the metal tape 20 to cover it, and then a metal band 8 is tightened over it, in explosion prevention. Subsequently, the tube 3 in this state is heated in a heating furnace, and evacuating is made. A special microcracks can be prevented from occurring in the vicinity of the mold match line L of the panel and thus a regenerated panel is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a cathode ray tube used in a television picture tube, a terminal display device, etc., for explosion-proof treatment, and an implosion-prevention metal band used for the explosion-proof treatment (hereinafter simply referred to as "metal band" Abbreviated as “”).

[0002]

2. Description of the Related Art Generally, a cathode ray tube is subjected to explosion-proof treatment by assembling a tube body of the cathode ray tube, exhausting the gas in the tube body, and after a certain period of time, heating and expanding metal around the panel portion. Although it is performed by fitting a band, the evacuation treatment of the pipe body is actually performed under high temperature heating in a heating furnace at about 400 ° C., for example, and the pipe body is exhausted after this exhaust treatment. Is taken out from the heating furnace, and the pipe is air-cooled to 25 ° C. in the taken out state.

For this reason, if the tubes are damaged after the exhaust and before the explosion-proof treatment, natural implosion may occur, and even a slight mechanical shock may be applied from the outside. , The tube may implode. In particular, such implosion increases as the cathode ray tube becomes larger and becomes flat panel.

Therefore, the applicant of the present invention, June 28, 1985
The above-mentioned implosion accident was solved by the invention technology disclosed in Japanese Patent Laid-Open No. 62-5533, which was filed on the date of application and published on January 12, 1987.

A method of manufacturing a cathode ray tube according to the invention is shown in FIG.
It will be briefly described with reference to FIGS. 4 is a view published in the above-mentioned publication, FIG. 4A is a front view of the cathode ray tube, FIG. 4B is a side view thereof, and FIG. 4C is a partial cross-sectional view of the main part thereof. 5 to 7 are views for reference only and show a metal band according to the related art.
5A is a partial side view of the annular metal band, FIG. 5B is a plan view seen from the inner peripheral surface thereof, and FIG. 6 is an enlarged side view of the portion indicated by the arrow Ma in FIG. 5A, FIG. 7 is FIG.
8 is an enlarged side view of a welded portion of one spot indicated by arrows Ma and Mb of A, FIG. A showing one state, FIG. B showing another state, and FIG. FIG. 4 is an enlarged side view of a main part of a cathode ray tube for explaining a mold match line and a protruding portion of the mold match line.

According to the invention technique disclosed in the above-mentioned prior application, a heat-resistant heat insulating tape 7 such as a glass cloth tape is provided on the outer periphery of the panel portion 1 of the tubular body 3 before the heating and exhausting step.
Is bonded, and a metal band 8 having both ends welded in a ring shape is fitted on the metal band in a preheated and expanded state, which is air-cooled and tightened, and then while heating the tube body 3 in this state. It is a method of manufacturing a cathode ray tube for exhausting.

Further, as will be described later, since the metal band 8 is generally poorly finished, when such a metal band 8 is used, the vicinity of the corner portion of the panel portion 1 and both end portions 11A of the metal band 8, 11B weld Ma
A thin piece 9 such as a steel tape having a small frictional resistance with the metal band 8 is adhered to the portion hit by the above-mentioned heat-resistant heat-insulating tape 7 by adhering the thin piece 9 so as to project further forward than this. Above, the technique of tightening the metal band 8 on the heat resistant heat insulating tape 7 so that the metal band 8 may be slid in from the front of the panel part 1 is disclosed.

Next, the above-mentioned "metal band 8 having a poor finish" will be supplementarily described. Poor finish is 1. Processing accuracy when the metal band 8 is cut into a band shape from a thin plate. It depends on the processing accuracy when the spot welding described below is performed on the metal band 8.

As shown in FIG. 5, the metal band 8 is formed in the shape of a quadrangle ring whose corners are rounded so as to fit the outer shape of the panel 1 as described above. Both ends 11A and 11B are spot-welded at, for example, 9 points to form a welded portion Ma. In addition, at each corner of the metal band 8, the pipe body 3 is
For example, a holder 12 for mounting on a cabinet of a television receiver is spot-welded at, for example, 8 places to form a welded portion Mb.

When the cutting accuracy is poor, the end portion 11 of the band is cut as shown by the arrow X in FIG.
The burrs 13 are generated on A and 11B, and the burrs 13 particularly generated on the end portion 11A on the tube body 3 side poses a problem. Also,
When the spot welding described above is performed, the arrow X in FIG.
As shown in a, it rises around the nugget 14 1
5 is formed, which is generated on the side of the tube 3 and becomes a problem. In particular,
When spot welding is performed while producing a splash, as shown in FIG. 7B, the protrusion 15 has a sharp shape, which is a serious problem.

The problem is that when such a "metal band 8 having a poor finish" is fitted into the panel 1, the burr 13 and the bulge 15 are heat-resistant insulating tape 7.
To directly contact the glass surface of the panel unit 1,
It will cause scratches. Alternatively, when the metal band 8 is fitted into the panel portion 1 without interposing the heat-resistant heat insulating tape 7, the metal band 8 directly contacts with the glass surface to cause scratches, and further,
When the glass is thermally distorted due to the heating of the metal band 8, and such scratches and distortions are generated, the tube body 3 becomes mechanically weak and easily damaged, and the heating and exhaust treatment is performed. At times, the tube body 3 is likely to be thermally damaged.

For these reasons, the thin piece 9 is useful for use, and the invention technology described in the above-mentioned publication discloses that the thin piece 9 is mounted near each corner of the panel portion 1 and the metal band 8 is fitted therein. I can do it smoothly.

[0013]

However, even if a metal band 8 having a good finishing process is used so that it is not necessary to take such measures against scratches, the following problems occur. That is, since the pipe body 3 undergoes the heating and exhausting process while the metal band 8 is attached, the pipe body 3 and the metal band 8 are heated to the high temperature close to 400 ° C. as described above, and the temperature of 25 ° C. Since the temperature is lowered to, the glass constituting the tubular body 3 and the metal band 8 have different coefficients of thermal expansion. Therefore, the outer peripheral surface of the panel portion 1 is subjected to the pressure of the metal band 8 and both are heated. Cause a relative shift.

As shown in FIG. 8, normally, the panel portion 1 is composed of a front surface portion 1A having an outer surface blend radius and a skirt portion 1B, which are molded by two different molds. Therefore, the height (out) is 0.2 between the two, depending on the size of the tube, on the mold match line L.
A protrusion D of about 0.3 mm is formed. The metal band 8 is mounted so as to cover the protruding portion D. Therefore, in particular, in the vicinity of the mold match line L at the four corners where the pressing force of the metal band 8 is most strongly received, the relative displacement is caused. It was found that a large number of microcracks based on the above were generated. It was found that the microcracks were generated when the protrusion D broke the heat resistant heat insulating tape 7 and rubbed against the metal band 8 under a pressure. It was also found that the glass fibers contained in the heat-resistant heat-insulating tape 7 were rubbed against the glass fiber contained in the heat-resistant heat-insulating tape 7 even when the protrusion D did not break.

When the tube body 3 becomes defective in another manufacturing process, the tube body 3 may be recycled for reuse. In particular, expensive large tubes are often reused. However, since the tube body in which this microcrack has occurred is subject to heating and external force in the manufacturing process of the cathode ray tube, damage and implosion are likely to occur based on the microcrack, and therefore such a panel part can be reused. You cannot do it. An object of the present invention is to prevent the occurrence of such microcracks.

[0016]

Therefore, according to the method of manufacturing a cathode ray tube of the present invention, the protruding portion generated on the mold match line L at the corner portion of the panel portion 1 of the tubular body 3 is subjected to the heating and exhausting step. The metal tape 20 (FIG. 1) is attached so as to cover D or to alleviate the step of the protrusion D, and then the heat-resistant heat-insulating tape with adhesive 7 is attached so as to cover the metal tape 20. Further, a metal band 8 was mounted thereon, and then the gas in the tube body was exhausted while heating the tube body 3 to obtain a cathode ray tube.

The means for alleviating the stepped portion of the projecting portion D has been solved by increasing the thickness of the metal tapes 20 and 30 (FIG. 2) that abut on the skirt portion 1B side of the mold match line L. The thickening method has a structure in which metal tapes are laminated in multiple layers.

Further, in order to prevent the generation of the microcracks, since the projecting portion D is not subjected to the pressing force by the metal band, the metal band having the above-mentioned shape is formed on at least the inner surface of each corner portion. After forming a groove or a rib protruding to the outside along the annular peripheral surface (FIG. 3), using a metal band having such a structure, after mounting a heat resistant heat insulating tape so as to cover the protrusion, The groove or rib was installed so as to cover at least the protruding portion of the corner of the panel portion, and then the gas inside the tube was exhausted while heating the tube to obtain a cathode ray tube.
The present invention was able to solve the above-mentioned problems by using such means.

[0019]

Therefore, according to the method of manufacturing a cathode ray tube and the metal band for implosion prevention of the present invention, it is possible to prevent the generation of microcracks in the vicinity of the mold match line of the panel portion.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method of manufacturing a cathode ray tube and a metal band for implosion prevention of the present invention will be described with reference to FIGS. FIG. 1 is a partially enlarged view of a panel portion of a cathode ray tube for explaining a first embodiment of a method for manufacturing a cathode ray tube according to the present invention. FIG. 1A is a perspective view thereof, and FIG. 2 is a cross-sectional view taken along the line AA of FIG. 2, and FIG. 2 is a partially enlarged view of the panel portion of the cathode ray tube for explaining the second embodiment of the method of manufacturing the cathode ray tube of the present invention. The perspective view and FIG.
FIG. 3 is a cross-sectional view taken along line AA of FIG. 3, and FIG. 3 shows a panel portion of a cathode ray tube for explaining a third embodiment of the method of manufacturing a cathode ray tube of the present invention and a metal band for preventing implosion used therein. A partially enlarged view, FIG. A is a perspective view thereof, and FIG. B is a cross-sectional view of a corner portion of the panel portion of FIG. In the following description, the same components as those of the cathode ray tube and the explosion-proof treatment structure of the related art will be designated by the same reference numerals and the description thereof will be omitted.

First, a method of manufacturing a cathode ray tube according to a first embodiment of the present invention and a structure of a metal tape used therefor will be described with reference to FIG. In FIG. 1, only the panel portion 1 of the tube body 3 which is a cathode ray tube is shown. As shown in FIG. A, the metal tape 20 according to one embodiment of the present invention is formed by stacking metal tapes having the same thickness so as to alleviate the step difference of the protrusion D generated in the mold match line L. Bonding was performed to form the laminated portion 20A. The metal tape 20 as described above is adhered to the entire corner portions of the panel portion 1 where the stress is most concentrated so as to cover the protruding portion D of the mold match line L.

In this case, as shown in cross section in FIG. 1B,
The metal tape 20 is adhered to each corner portion so that the laminated portion 20A can be located on the skirt portion 1B side of the protrusion D so that the step difference of the protrusion D on the skirt portion 1B side can be reduced as much as possible. Then, at least the outermost metal layer 20B of the metal tape 20 covers the protrusion D.

After that, although not shown, a heat-resistant heat-insulating tape 7 such as a glass cloth tape whose both surfaces are coated with an adhesive is coated on the entire panel portion 1 so as to cover the metal tapes 20. Adhere and attach to the circumference. And, on this, each corner part is made of cold rolled steel plate and the panel part 1
The metal band 8 formed in the shape of a quadrangle ring having a rounded shape along each of the corners is preheated and fitted in an expanded state. After that, the metal band 8 can be air-cooled and tightened to pressurize the panel portion 1.

Then, after that, the tube body 3 in this state is put into a heating furnace and, for example, at a high temperature of 400 ° C., the tube body 3 is placed.
The desired cathode ray tube can be obtained by exhausting the gas inside and taking out from the heating furnace after the exhaustion is completed. Aluminum was used as the material of the metal tape 20 in this embodiment.

Next, a method of manufacturing a cathode ray tube according to a second embodiment of the present invention will be described with reference to FIG. As the metal tape in this example, a metal tape 30 having a structure in which metal tapes having substantially the same width and thickness were bonded together was used.
Although this figure shows the metal tape 30 having a laminated structure of two layers, it may have three or more layers.

As shown in the figure, such a metal tape 30 is adhered to the corners of the panel portion 1 near the protrusion D on the mold match line L on the side of the skirt portion 1B to apparently protrude. The steps D of the portion D are made substantially flat, and then the heat-resistant heat insulating tape 7 is wound so as to cover these and cover the protruding portion D so as to cover the front portion 1A. Then, thereafter, as in the first embodiment, the panel unit 1
If the metal band 8 is tightened and the tube body 3 in that state is heated and exhausted, a desired cathode ray tube can be obtained.

Stainless steel was used as the material of the metal tape 30 in this embodiment, and the metal tape 30 was constructed by stacking two stainless steel sheets. A heat resistant heat insulating tape 7 was wound on this.

According to the first and second embodiments, the protrusion is based on the difference in the coefficient of thermal expansion between the glass of the panel portion 1 and the metal band 8 which expand during the heating and exhausting process of the tube body 3. Even if the portion D and the metal band 8 are relatively deviated from each other, or even if stress is attempted to concentrate on the projecting portion D due to the pressing force of the metal band 8, the metal tapes 20 and 30 cause the metal band 8 to intervene. Since the protruding portion D was not directly subjected to the pressing force, the above-mentioned generation of microcracks was not found.

The metal tapes 20 and 30 are
It is considered that the metal band 8 disperses the pressing force applied to the mold match line L at the corner portion of the panel portion 1 to reduce the degree of stress concentration. Particularly, in the case of the first embodiment, since the aluminum metal tape 20 covers the protruding portion D, the linear protruding portion D is changed to a planar shape, and the stress concentration due to the pressing force is alleviated accordingly. You can Moreover, since aluminum has low rigidity, it easily fits into the protrusion D and the like, and also functions as a cushion.

In view of this latter characteristic, the stainless steel metal tape 30 used in the second embodiment, which has a slightly high rigidity, is slightly inferior to the role of aluminum, but this metal tape 30 is as described above. The step difference can be alleviated, and the stress concentration due to the pressing force can be alleviated accordingly. Moreover, in both of the embodiments, the heat-resistant heat-insulating tape 7 is wound around the entire circumference of the panel 1 so as to cover the metal tapes 20 and 30, so that the stress concentration applied to the protrusion D is alleviated. be able to.

Next, a method of manufacturing a cathode ray tube and a metal band for preventing implosion according to a third embodiment of the present invention will be described with reference to FIG. The method of preventing the generation of microcracks according to the third embodiment is different from that of the second embodiment.
The metal tapes 20 and 30 described above are not used.

In this embodiment, a metal band 40 having a structure different from that of the metal band 8 is used. This metal band 8
Has a rounded corner along each corner of the panel portion 1 and is formed in a quadrilateral ring shape. At least the inner surface of each corner is provided with a strip along the annular peripheral surface. That is, the groove 41 is formed.
These line grooves 41 are ribs when viewed from the outer periphery of the metal band 8.

The grooves 41 are formed by the metal band 4
It can be formed by stamping 0 with a sheet metal or the like before it is formed into a ring shape by the spot welding.
Further, the groove 41 may be formed around the entire inner surface of the metal band 40.

In the method of manufacturing a cathode ray tube according to the third embodiment of the present invention, the heat resistant heat insulating tape 7 is attached so as to cover the protruding portion D formed on the mold match line L of the panel portion 1, and thereafter, The metal band 40 having the above-described structure and having the holder 12 is attached to the panel portion 1 in the vicinity of each corner so that each groove 41 of the metal band 40 covers at least the projecting portion D of the corner portion of the panel portion 1. Then, after heating the tube body 3 in such a mounted state and exhausting the gas in the tube body 3, a desired cathode ray tube can be obtained.

In this embodiment, since the protrusion D on the mold match line L at the corner of the panel portion 1 is not subjected to the pressure applied by the metal band 40, the above-mentioned microcracks are present in the vicinity of the mold match line L. It never happens.

[0036]

As is clear from the above description, when the method of manufacturing a cathode ray tube and the implosion preventing metal band of the present invention are used, microcracks are not generated in the vicinity of the mold match line of the panel portion, and therefore, There are many excellent effects such as the ability to collect a good panel portion free from microcracks from a defective cathode ray tube caused by another trouble in the manufacturing process, and to reuse it.

[Brief description of drawings]

FIG. 1 is a partially enlarged view of a panel portion of a cathode ray tube for explaining a first embodiment of a method of manufacturing a cathode ray tube according to the present invention, FIG. 1A is a perspective view thereof, and FIG. It is sectional drawing on the AA of A.

FIG. 2 is a partially enlarged view of the panel portion of the cathode ray tube for explaining the second embodiment of the method of manufacturing a cathode ray tube according to the present invention, where FIG. A is a perspective view thereof and FIG. It is sectional drawing on the AA of A.

FIG. 3 is a partially enlarged view of a panel portion of a cathode ray tube for explaining a third embodiment of the method of manufacturing a cathode ray tube according to the present invention and an implosion preventing metal band used therein, FIG. FIG. 3 is a perspective view and FIG. 3B is a sectional view of a corner portion of the panel portion of FIG.

4A and 4B are views for explaining a conventional method for manufacturing a cathode ray tube, wherein FIG. 4A is a front view of the cathode ray tube, FIG. 4B is a side view thereof, and FIG. It is a figure.

5 shows a conventional implosion prevention metal band, FIG. 5A is a partial side view of the implosion prevention metal band formed in an annular shape, and FIG. 5B is a plan view seen from the inner peripheral surface thereof. Is.

FIG. 6 is an enlarged side view of a portion indicated by an arrow Ma in FIG. 5A.

FIG. 7 is an enlarged side view of a welded portion of one spot indicated by arrows Ma and Mb in FIG. 5A, in which FIG. A shows one state and FIG. B shows another one state. is there.

FIG. 8 is an enlarged side view of a main part of a cathode ray tube for explaining a mold match line and a protruding part of the mold match line.

[Explanation of symbols]

 1 Panel Part 1A Front Part of Panel Part 1B Skirt Part of Panel Part 1 2 Funnel Part 3 Tubular Body 7 Heat Resistant Insulation Tape 8 Metal Band 11A End of Metal Band 11B End of Metal Band 12 Holder 13 Burr 14 Nugget 15 Rise 20 Metal tape according to the first embodiment of the present invention 30 Metal tape according to the second embodiment of the present invention 40 Metal band for implosion prevention 41 of the present invention 41 Groove or rib D Protrusion L on mold match line L Mold match line

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[Procedure amendment]

[Submission date] July 8, 1993

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

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[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 3

[Correction method] Change

[Correction content]

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0001

[Correction method] Change

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[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Machine, terminal display device a cathode ray tube used for such performing <br/> explosion process preparation and explosion process used to implosion preventive metal band (hereinafter, simply referred to as "metal strap") relates to .

[Procedure amendment]

[Submission date] July 28, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 3

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

A method of manufacturing a cathode ray tube according to the invention is shown in FIG.
It will be briefly described with reference to FIGS. 4 is a view published in the above-mentioned publication, FIG. 4A is a front view of the cathode ray tube, FIG. 4B is a side view thereof, and FIG. 4C is a partial cross-sectional view of the main part thereof. 5 to 7 are views for reference only and show a metal band according to the related art.
Figure 5A some positive elevational view of a metal band formed in a ring, FIG. B is a side view as seen from the outer circumferential surface, FIG. 6 is an enlarged side view of a portion indicated by an arrow Ma in FIG. 5A Yes, FIG. 7 is FIG.
FIG. 8 is an enlarged side view of a welded portion of one spot indicated by arrows Ma and Mb of A, FIG. A showing one state, FIG. B showing another state, and FIG. FIG. 4 is an enlarged side view of a main part of a cathode ray tube for explaining a mold match line and a protruding portion of the mold match line.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

When the cutting accuracy is poor, the end portion 11 of the band is cut as shown by the arrow X in FIG.
The burrs 13 are generated on A and 11B, and the burrs 13 particularly generated on the end portion 11A on the tube body 3 side poses a problem. Also,
When the spot welding is performed, as shown in FIG. 7A , a bulge 15 is formed around the nugget 14,
This occurs on the tube body 3 side and becomes a problem. In particular, when spot welding is performed while producing a splash, as shown in FIG. 7B, the protrusion 15 has a sharp shape,
It matters a lot.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

The problem is that when such a "metal band 8 having a poor finish" is fitted into the panel 1, the burr 13 and the bulge 15 are heat-resistant insulating tape 7.
To directly contact the glass surface of the panel unit 1,
It will cause scratches. Alternatively, when the metal band 8 is fitted into the panel portion 1 without interposing the heat-resistant heat insulating tape 7, the metal band 8 directly contacts with the glass surface to cause scratches, and further,
When the glass is thermally distorted due to the heating of the metal band 8, and such scratches and distortions occur, the tube body 3 is mechanically weakened, and the tube body 3 is thermally damaged during the heating and exhausting process. Is likely to occur.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method of manufacturing a cathode ray tube and a metal band for implosion prevention of the present invention will be described with reference to FIGS. FIG. 1 is a partially enlarged view of a panel portion of a cathode ray tube for explaining a first embodiment of a method for manufacturing a cathode ray tube according to the present invention. FIG. 1A is a perspective view thereof, and FIG. 2 is a cross-sectional view taken along the line AA of FIG. 2, and FIG. 2 is a partially enlarged view of the panel portion of the cathode ray tube for explaining the second embodiment of the method of manufacturing the cathode ray tube of the present invention. The perspective view and FIG.
FIG. 3 is a cross-sectional view taken along line AA of FIG. 3, and FIG. 3 shows a panel portion of a cathode ray tube for explaining a third embodiment of the method of manufacturing a cathode ray tube of the present invention and a metal band for preventing implosion used therein. A partially enlarged view, FIG. A is a side view thereof, and FIG. B is a cross-sectional view of a corner portion of the panel portion of FIG. In the following description, the same components as those of the cathode ray tube and the explosion-proof treatment structure of the related art will be designated by the same reference numerals and the description thereof will be omitted.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 3

[Correction method] Change

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FIG. 3 is a partially enlarged view of a panel portion of a cathode ray tube for explaining a third embodiment of the method of manufacturing a cathode ray tube according to the present invention and an implosion preventing metal band used therein, FIG. A side view and FIG. 6B are cross-sectional views of the corner portion of the panel portion of FIG.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

Figure 5 shows the implosion preventive metal band of the prior art, FIG 5A some positive elevational view of the implosion preventive metal band formed in a ring, the side figure B is viewed from the outer peripheral surface It is a side view.

Claims (4)

[Claims] 1. A method of manufacturing a cathode ray tube having a heating / evacuating step, in which, before the heating / evacuating step, a linear protrusion is apparently formed on a mold match line at a corner portion of a panel portion of the tubular body, and the surface is apparent. The heat-resistant heat-insulating tape is mounted on the protruding part, and a metal band for implosion prevention is further mounted on the protruding part, and then the gas inside the tube is heated while heating such a tube. A method of manufacturing a cathode ray tube, which comprises exhausting. 2. A method of manufacturing a cathode ray tube, comprising bonding a tape-shaped metal along a mold match line of a panel portion of the cathode ray tube. 3. An implosion prevention metal band formed in the shape of a quadrilateral ring, each corner portion having a rounded shape. At least on the inner surface of each corner portion, a groove is formed along the annular peripheral surface. A metal band for implosion prevention, which is characterized by being formed. 4. A method of manufacturing a cathode ray tube having a heating / evacuating step, wherein a heat-resistant tape is attached so as to cover a protruding portion formed on a mold match line of a panel portion of the tubular body before the heating / evacuating step, After that, the implosion prevention metal band according to claim 3 is attached to the pipe body such that each of the grooves of the metal band covers at least the projecting portion of the corner portion of the panel portion of the pipe body, and then such a pipe body. A method for manufacturing a cathode ray tube, characterized in that the gas inside the tube is exhausted while heating the tube.