JPS6028102B2 - Shadow mask molding method and molding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding method and a molding apparatus for obtaining a shadow mask for a color picture tube with few local irregularities.

Since the shadow mask used in a color picture tube must perform a color selection function, the distance from the panel and the curved surface of the shadow mask must be accurately maintained at predetermined values and shapes. However, with conventional molding methods or devices, it is not always possible to obtain a shadow mask with an accurate curved surface, and local unevenness may occur during welding to a mask frame. The present invention has been made to eliminate the above-mentioned deformation of the shadow mask, and the present invention will be described below based on embodiments along with drawings while comparing with the following methods.

FIG. 1A is a diagram showing the main parts of a conventional molding apparatus for molding a shadow mask and its manufacturing process.

As shown in FIG. 1A, the device is a die (supporting body) that supports a perforated flat plate 1 to become a shadow mask and has a recessed part 2.
3, and a punch (pressing body) 5 having a curved convex portion 4 at its lower part. 6 is an ejector for taking out the molded shadow mask from the die 3.

First, the perforated flat plate 1 is installed in the die 3, and the outer peripheral portion 7 of the flat plate 1 is supported. Thereafter, as shown in the opening of FIG. 1, the punch 5 is pushed into the recess 2 of the die 3, and the perforated flat plate 1 is press-molded to form the skirt portion 7'. However, as mentioned above, deformation occurs in the shadow mask in conventional molding equipment of this type, and when the punch 5 and the die 3 are inserted, the gap between the side walls of the punch 5 and the die 3 is limited to the area around the shadow mask. A constant gap (thickness of flat plate 1 100.2~
0.4 side), so the punch 5 punches the recess 2 of the tar 3.
It is thought that the resistance state (sliding state) of the skirt portion 7' when the peripheral green skirt portion 7' of the perforated flat plate 1 is slid into the hole influences the warpage. That is, the second
As shown in Figure A, 4 is sandwiched between two sides of the shadow mask.
The corners of the shadow mask undergo plastic processing, and the skirt portion 7' can be molded without warping and properly aligned with the mask frame 8. However, as shown in the opening of Figure 2, the skirt portion 7' The central part of the side is subjected to relatively weak anti-friction processing, and the skirt part 7' is bent outward, causing the mask frame 8
There is a gap of about 1 to 2 sides at the tip. Also the second
As shown in FIG. 3C, the plastic working becomes even weaker at the center portion on the side of the shadow mask, and the skirt portion 7' is further warped outward by about 2 to 4 ribs. As described above, in the conventional method, the skirt portion 7' of the shadow mask 1' is curved outward, so as shown in FIG. As a result, the shadow mask 1' is deformed, and due to this deformation, the shadow mask 1' is locally deformed by the heating of the electron beam during operation of the color picture tube, causing color misregistration.

Therefore, in the present invention, when molding a shadow mask, the perforated flat plate is molded so that the gap between the side walls of the punch and the die is larger at the corner of the shadow mask than at the side. Eliminated mask deformation. FIG. 4 is an enlarged view showing a plane when the punch 5 and die are combined, which is an embodiment of the present invention.

In the figure, the cross section of the punch 5 is shown by hatching, its outer diameter is shown by a solid line 9, the inner diameter of the conventional die 3 is shown by a dotted line 10, and the die according to the present invention is shown by a dashed line 11.
That is, in the conventional case, the distance between the side walls of the die 3 and the punch 5 was constant over the entire circumference of the shadow mask, but in the present invention, the distance between the side walls of the die 3 and the punch 5 is constant over the entire circumference of the shadow mask, but in the present invention, the distance between the side walls of the die 3 and the punch 5 is constant at the corner 12 of the shadow mask, It is made larger than 14. In one example of the present invention, the gap distance between the corner portions 12 is made larger by 0.3 to 0.6 sides than the thickness of the shadow mask, and the edge portion 1
The same distance between the center portions of the short sides 14 is approximately the same as the thickness of the shadow mask, and the same distance between the center portions of the short side portions 14 is approximately 0.2 to 0.4 times larger than the thickness of the shadow mask.

By molding the shadow mask by giving a difference in the gap distance between the die 3 and the punch 5 in this way, the obtained shadow mask can be warped even if there is warpage at the skirt part of the outermost side and the short side. This is a shape that allows proper iron fitting to the side wall of the mask frame without warping.

As explained above, in the present invention, a perforated flat plate is press-molded so that the side wall gap distance between the concave portion of the support body and the curved convex portion of the pressing body is larger at the corner of the shadow mask than at the same side. Therefore, the obtained shadow mask can be welded to the mask frame without warping, and color shift during operation of the picture tube can be eliminated.

[Brief explanation of drawings]

Figures 1A and 1C are diagrams showing the process of a general shadow mask molding method, Figures 2A, 2C, and 3 are cross-sectional views of main parts to explain the drawbacks of the conventional molding method. FIG. 4 is a plan view of essential parts showing an embodiment of the shadow mask molding method of the present invention. 1... Perforated flat plate, 1'... Shadow mask, 2... Concavity, 3... Tear, 4...
...Curved convex portion, 5...Punch, 6"""Ejector, 7'""" Force-Urakibe, 8...Mask frame. Figure 2 Figure 1 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. When molding a shadow mask by supporting a perforated flat plate with a support body having a concave portion and pressing the perforated flat plate with a pressing body having a curved convex portion that can be inserted into the concave portion, A method for molding a shadow mask, characterized in that pressing is carried out such that a side wall gap between a curved convex portion of a pressing body and a concave portion of the support body becomes larger at a corner of the shadow mask. 2. A pressing body having a curved convex portion and a support body having a concave portion through which the curved convex portion can be inserted and supporting a perforated flat plate, and molding a shadow mask by pressing the perforated flat plate with the pressing body. A molding apparatus for a shadow mask, characterized in that the pressing body and the support body are formed such that a side wall gap between the curved convex portion and the concave portion becomes larger at a corner of the shadow mask. .