JPH04179025A - Manufacturing method of electrode for electron gun - Google Patents

Abstract

PURPOSE:To process a pass-through hole for an electron beam into a shape of an electrode hole to have no shift between the hole and a taper part and a superior coaxial degree by shaping the hole in the same process and by means of a pair of punching tools. CONSTITUTION:A taper coining processing is applied to the edge part of an electron beam pass-through hole 11 by means of a punching dies 21 having a taper part 212, and at the same time, the electron beam pass-through hole 11 is punched by means of a punch equipped with a cutting edge part 201. Thus, in the process of punching an electrode 10 a taper forming and a punching forming are performed in the same process and by means of a pair of punching tools (punch, dies) 20, 21 so that it can be processed with the same core without causing any shift between its edge part and the taper part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an electron gun electrode for a cathode ray tube, and more particularly to a method for manufacturing an electrode that improves the withstand voltage characteristics of an electron gun.

[Conventional technology]

Conventionally, the aperture of the electron gun main lens of color cathode ray tubes is enlarged. In other words, as a method that can improve focusing performance by increasing the aperture, for example, Japanese Patent Application Laid-Open No. 58-13
As shown in Japanese Patent No. 3743, an electron gun is known in which the diameter of the beam passage aperture of the cup-shaped electrode constituting the main lens is expanded to the maximum limit for press processing.

FIG. 2 shows (a) a plan view of the cup-shaped electrode described above during press working, and (b) a sectional view taken along the line xx' in (a). In the figure, main lens electrode 1
0 consists of a cup-shaped part, and three openings 11 lined up on a straight line in the X-X' force direction are formed by punching in a press process. These apertures 11 are formed by removing the cylindrical portion of the previous main lens electrode, thereby forming the aperture spacing 12.
The width of the opening 11 is narrowed to 0.5 to 1.5 times the thickness t of the material, which is the limit in terms of press working, and the diameter of the opening 11 is enlarged.

For example, in the case of the main lens electrode 10 to be housed in the neck of a color cathode ray tube with an outer diameter of 29 mm, the diameter d of the aperture 11 can be set to about 6.41 with a pitch between the apertures of 6.6 mm. This is approximately 20% larger than the cylindrical inner diameter of the previous main lens electrode, that is, the beam passage aperture.
By using this main lens electrode, it is possible to improve the focus characteristics of the color cathode ray tube.

When the aperture of the main lens electrode as described above is formed by simple punching in a press process, as shown in FIG.
have. This edge portion 15 easily causes discharge between the electrodes due to the high voltage applied to the main lens electrode 10.
Due to the high voltage characteristics of cathode ray tubes, this will lead to disadvantageous results. Furthermore, among the electrodes constituting the main lens, near the electron beam passage hole of the grid electrode on the low potential side that opposes the grid electrode on the high potential side, the electric field concentration is large and stray emission is likely to occur. It has been experimentally found that in order to alleviate the electric field concentration near the electron beam passage hole, it is sufficient to form a tapered or rounded chamfer on the edge of the electron beam passage hole.

For this reason, conventionally, after press punching, as shown in FIG. 4, machining was added to add a chamfered taper portion 16 to the hole edge on the electrode facing surface side 14 of the punched hole 11. Alternatively, as shown in FIG. 5, the edges of the punched holes 11 are subjected to barrel polishing, chemical polishing, etc. to make the edge portions 15 rounded.

Furthermore, as shown in FIG. 6, the punching is composed of two steps, (a) first, in the first step, the beam passage opening is half punched out using a half punch 20 having a cutting edge part 201 and a tapered part 202; At the same time as the processing, the taper portion 202 performs coining on the hole edge, and (b) next, in the second step, the beam passage opening is punched out using the punch 30.

[Problem to be solved by the invention]

The electrode manufacturing method using mechanical processing as described above is not only inefficient and increases costs, but also has the problem that the tapered part cannot be machined concentrically with respect to the beam passage hole, leading to variations in focus characteristics. was holding. In addition, barrel polishing, chemical polishing, etc. leave particles on the edge of the hole, resulting in deterioration of withstand voltage characteristics. Therefore, it has been desired to develop a processing method for main lens electrodes that eliminates these problems.

An object of the present invention is to provide a method for manufacturing an electron gun electrode that consistently processes the tapered part and punches the hole through highly efficient press working, and also enables the taper process to be performed completely concentrically with respect to the beam passage hole. Our goal is to provide the following.

[Means to solve the problem]

In order to achieve such an object, the method for manufacturing an electron gun electrode according to the present invention involves performing a tapered coining process on the hole edge of the electron beam passage hole using a punching die provided with a tapered portion, and at the same time forming a tapered coining process on the hole edge of the electron beam passage port. The electron beam passage hole is punched out using a hole punch equipped with a hole punch.

[Effect]

In the present invention, when punching a hole in an electrode, taper forming and punching are performed in the same process and using a set of hole punching tools (punch, die), so the misalignment between the taper part of the hole edge and the hole part is reduced. It is completely removed and processed concentrically.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. FIGS. 1(a), (b), and (Q) are cross-sectional views showing the processing state of the process of the present invention. In the same figure.

20 is a hole punch, and this punch 20 is equipped with a cutting edge portion 201 at the tip. Reference numeral 21 denotes a hole punching die, and this hole punching die 21 has a die hole 211 having a dimension D' slightly larger than the dimension of the tip cutting edge 201 of the hole punch 20, and a tapered portion outwardly thereof. It is equipped with 212.

First, as shown in Figure Ca), an electrode semi-finished product 10', which has been formed into a cup shape in advance, is held on the upper surface of a mounting table with the electrode facing surface side 14 facing upward by a transfer device (not shown). Next, as shown in FIG. 6(b), as the press descends, the punching die 21 also descends, and a tapered coining process is performed on the hole edge of the electrode semi-finished product 10' at the bottom dead center position. It can be done. In addition, at this time, hole punch 20
rises and presses the semi-finished electrode 10'.

At the same time as this tapered coining process, the hole punch 20 further rises and punches a hole corresponding to the edge of the hole, and the scrap part 18 is processed to the point of breaking at once in this process and separated from the semi-finished product 10'. and is ejected from the mold.

According to this embodiment, the beam passing hole 11 is formed in the electrode 10 by simultaneously performing the punching process of the beam passing hole and the tapered coining process on the edge of the hole, as shown in FIG. 1(c). A tapered chamfer 16 can be formed on the side edge 14 of the electrode facing surface completely concentrically with the beam passage hole 11.

〔Effect of the invention〕

As explained above, in the present invention, the electron beam passing hole of the electron gun electrode is formed in the same process with high precision using a set of punches and dies, so there is no misalignment between the hole and the tapered part. It can be processed into an electrode hole shape with excellent coaxiality, improving the focus characteristics and withstand voltage characteristics of the cathode ray tube. Furthermore, since it can be processed with high efficiency by press-through processing, the electrode processing cost can be significantly reduced.

[Brief explanation of drawings]

1(a), 1(b), and 1(c) are cross-sectional views of steps illustrating one embodiment of the method for manufacturing an electron gun electrode according to the present invention;
The figure is a plan view of the cup-shaped electron gun electrode. 3 is a sectional view of the main part of the beam passage hole formed by the conventional punching process, and FIG. 4 is a chamfering process at one end of the beam passage hole formed by the punching process shown in FIG. 3. Figure 5 is a sectional view of the main part to explain the state in which
FIGS. 6(a) and 6(b) are cross-sectional views of main parts for explaining the state in which the beam passage hole shown in the figure has been polished, and FIGS. 6(a) and 6(b) are cross-sectional views of steps for explaining another conventional punching method. 10... Electrode, 10'... Electrode semi-finished product, 11.
...Electron beam passage hole, 16...Tapered chamfered part,
18...Scrap part, 20...(b)

Claims (1)

[Claims] 1. A method for manufacturing an electron gun electrode, which comprises simultaneously performing taper processing and punching of the electron beam passing hole of an electrode component in the electron gun electrode having an electron beam passing hole.