JPH08264114A - Device for molding shadow mask for color picture tube - Google Patents

Abstract

PURPOSE: To provide a molding device for molding a mask body by press so that deformation may not occur. CONSTITUTION: This is a device for molding a shadow mask for a color picture tube, which is equipped with a punch having a molding face consisting of a convex corresponding to the effective face of a shadow mask, an upper mold 41 having a blank holder 40 provided around this punch, and a lower mold 43 having a knock out 21 having a molding face consisting of a concave corresponding to the effective face of the shadow mask and a die 42 provided around this knock out. Each opposite face of the blank holder 40 and the die 41 are provided with uneven parts 44a and 44b to engage with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask forming apparatus for a color picture tube.

[0002]

2. Description of the Related Art Generally, in a color picture tube, as shown in FIG. 4, a phosphor screen 3 made of a phosphor layer of three colors is formed on the inner surface of an effective portion 2 having a curved surface of a panel 1. A shadow mask 4 is disposed inside the shadow mask 4 so as to face the. On the other hand, the electron gun 7 is arranged in the neck 6 of the funnel 5. Then, the three electron beam 8 emitted from the electron gun 7 is deflected by the magnetic field generated by the deflecting device 9 mounted outside the funnel 5, and the phosphor screen 3 is horizontally moved through the shadow mask 4.
A structure for displaying a color image is formed by vertical scanning.

The shadow mask 4 is for selecting the three electron beams 8 emitted from the electron gun 7 so that they are correctly incident on the three-color phosphor layer, and the mask body 11 facing the phosphor screen 3 is selected. And a mask frame 12 attached to the periphery of the mask body 11.
The mask body 11 has no electron beam passage holes around the effective surface 13 in which a large number of electron beam passage holes are formed in a predetermined array on a curved surface corresponding to the inner surface shape of the effective portion 2 of the panel 1. Skirt part 15 through ineffective part 14
Is formed, and the bead portion 16 is provided on the ineffective portion 14.

Such a mask body 11 is conventionally manufactured by press-molding a flat plate-shaped flat mask in which a predetermined electron beam passage hole is formed. As shown in FIGS. 5 and 6, the molding apparatus includes an upper die 20 having a punch 18 and a blank holder 19 provided around the punch 18, a knockout 21 facing the punch 18 and a knockout 21. A die 22 that is provided around and faces the blank holder 19
And a lower mold 23 having. The punch 18 has an inner punch 25a having a molding surface formed of a convex curved surface corresponding to the effective surface of the mask main body, and an annular recess 24 for forming a bead portion on the periphery of this molding surface, and the mask main body. Outer punch 25b for molding a non-effective portion in the peripheral portion of the effective surface. On the other hand, the knockout 21
The shadow mask has a molding surface corresponding to the effective surface of the shadow mask, and an annular convex portion 2 for molding a bead portion together with the annular concave portion 24 of the punch 18 in the peripheral portion of the molding surface.
6 is provided.

In the molding of the mask main body by this molding apparatus, after the flat mask is positioned on the die 22, the blank holder 19 is lowered together with the inner punch 25a and the outer punch 25b, and the blank holder 19 and the die 22 are moved. As shown in FIG. 6,
The non-perforated portion around the flat mask 28 is bent into an L shape and held. Then, the punch 18 is lowered, and the inner punch 25a and the knockout 21 are used to overhang and form an effective surface having a curved surface in which a large number of electron beam passage holes are formed, and a bead portion is formed. Subsequently, the punch 18 is lowered to push down the knockout 21, and the non-hole portion held by the blank holder 19 and the die 22 is slid between the outer punch 25b and the die 22 to draw the skirt portion. At the bottom dead center, the outer punch 25b is used to form an ineffective portion.

Conventionally, the mask main body 11 is mainly made of a low carbon steel plate such as aluminum killed steel, and the bead portion 16 of the ineffective portion 14 is formed by the low carbon steel plate. At the time of molding, the effective surface forming portion is pulled in the radial direction to facilitate plastic deformation and enhance the shape retention strength of the mask body 11 after molding.

However, with such a bead portion 16 alone,
High tension is used for the mask body made of low thermal expansion material such as amber (iron / nickel alloy) which has been used in recent years with flattening, large size and high definition of color picture tubes. Therefore, there is a problem that a sufficient effect cannot be obtained. That is, when a mask main body made of a low thermal expansion material such as amber is molded by the above-mentioned molding apparatus, the spring back after the molding causes the mask main body to be compressed as shown in FIG.
As shown in (a), wavy irregularities 30 are formed on the effective surface 13, or local depressions 31 as shown by a broken line in (b) are formed, which makes it difficult to form a predetermined curved surface. Further, as shown by the angle θ in FIG. 8, the opening of the skirt portion 15 to the outside becomes large, which makes it difficult to insert the skirt portion inside the mask frame, and the effective surface 13 may be deformed.

[0008]

As described above, in the mask body of the shadow mask of the color picture tube, a large number of electron beam passage holes are formed on the effective surface which is a curved surface corresponding to the inner surface shape of the effective portion of the panel. The structure is such that a skirt portion is formed in the peripheral portion of this effective surface through an ineffective portion in which an electron beam passage hole is not formed, and a bead portion is provided in the ineffective portion. It is manufactured by press-molding a flat-plate-shaped flat mask on which is formed.

For the press forming, a forming apparatus including an upper die having a punch and a blank holder provided around the punch and a lower die having a knockout and a die provided around the knockout is used. ing. The punch has an inner punch having a molding surface consisting of a convex curved surface corresponding to the effective surface of the mask main body, and an annular recess for forming a bead portion in the peripheral portion of this molding surface, and the effective surface of the mask main body. And an outer punch that forms an ineffective portion in the peripheral portion of the. On the other hand, the knockout has a molding surface composed of a concave curved surface corresponding to the effective surface of the mask body, and an annular convex portion for molding the bead portion together with the annular concave portion of the punch is provided in the peripheral portion of this molding surface. Has become.

The bead portion of the mask body is made of a low carbon steel sheet such as aluminum-killed steel that has been mainly used in the past, and the effective surface forming portion is pulled in the radial direction during molding to facilitate plastic deformation of the mask body. In addition, the shape retention strength of the effective surface of the mask body after molding is increased.

However, with such a bead portion alone, a mask body made of a low thermal expansion material such as amber, which has recently been used in accordance with flattening, enlargement and high definition of a color picture tube, has a problem. Since the material has high tension, there is a problem that a sufficient effect cannot be obtained.

That is, when a mask body made of a low thermal expansion material such as amber is molded by the above-mentioned molding apparatus, wavy unevenness or local dents are generated on the effective surface due to springback after molding, and a predetermined curved surface is formed. Difficult to mold,
Further, the opening of the skirt portion to the outside becomes large, which makes it difficult to insert the skirt portion inside the mask frame, and there is a problem that the effective portion may be deformed.

The present invention has been made in order to solve the above problems, and does not deform the mask main body made of a low carbon steel plate, in particular, the mask main body made of a low thermal expansion material such as amber. It is an object of the present invention to configure a molding apparatus capable of press molding.

[0014]

In order to achieve the above object, in the present invention, a punch having a molding surface formed of a convex curved surface corresponding to the effective surface of the shadow mask and a blank holder provided around the punch are provided. For a color picture tube having an upper die having the same, a knockout having a molding surface formed of a concave curved surface facing the punch and corresponding to the effective surface of the shadow mask, and a lower die having a die provided around the knockout and facing the blank holder. In the shadow mask forming apparatus, the blank holder and the die are provided with concavo-convex portions that engage with each other on the respective facing surfaces.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 and FIG. 2 show one embodiment of the apparatus for forming a shadow mask for a color picture tube. This molding apparatus includes an upper die 41 having a punch 18 and a blank holder 40 provided around the punch 18, a knockout 21 facing the punch 18, and the blank holder 4 provided around the knockout 21.
0 and a lower die 43 having a die 42 facing each other. The punch 18 has a molding surface formed of a convex curved surface corresponding to the effective surface of the mask body of the shadow mask, and an annular recess 24 for molding a bead portion on the effective surface of the mask body is provided in the peripheral portion of this molding surface. The inner punch 25a,
And an outer punch 25b that forms an ineffective portion around the effective surface of the mask body. Meanwhile, knockout 21
Has a molding surface composed of a concave curved surface corresponding to the effective surface of the mask body of the shadow mask, and for molding the bead portion on the effective surface of the mask body together with the annular recess 24 of the inner punch 25a in the peripheral portion of this molding surface. The annular convex portion 26 is provided.

The punch 18 of the upper mold 41 and the lower mold 43
The structure of the knockout 21 and the knockout 21 are almost the same as those of the conventional molding apparatus for shadow masks for color picture tubes. Section 44a,
44b is provided.

The mask body is molded by this molding apparatus as follows.

First, a flat plate-shaped flat mask 28 having a large number of electron beam passage holes formed in a predetermined portion on the die 42.
After positioning, the blank holder 40 is lowered together with the inner punch 25a and the outer punch 25b, and the non-perforated portion 14 around the flat mask 28 is held by the blank holder 40 and the die 42.
At this time, the blank holder 4 is attached to the non-hole portion 14.
0 and the wavy bead 4 by the wavy concavo-convex portions 44a and 44b provided on the respective facing surfaces of the die 42 and engaging with each other.
6 is held in the molded state.

Next, the punch 18 is lowered, and the inner punch 25a and the knockout 21 are used to bulge and form the effective surface 13 having a curved surface on which a large number of electron beam passage holes are formed. 24 and annular protrusion 26 provided on the knockout 21
The bead portion 16 is molded by and.

Then, the punch 18 is lowered, the knockout 21 is pushed down, and the blank holder 40 and the die 4 are pressed.
At the bottom dead center, the outer punch 25 is slid while the non-hole portion 14 held by 2 is slid between the outer punch 25b and the die 42 to draw the skirt.
Form the ineffective part by b.

As described above, the corrugated concave and convex portions 44a are engaged with the respective opposing surfaces of the blank holder 40 and the die 42.
, 44b are provided, the blank holder 40 and the die 42 hold the non-hole portion around the flat mask 28 at the time of molding, and the corrugated beads 46 are formed by the uneven portions 44a, 44b. Thereby, the tensile force for pulling the effective surface forming portion of the flat mask 28 in the radial direction is increased, and the effective surface forming portion is easily plastically deformed sufficiently.

Therefore, when the mask main body is molded by the above-mentioned molding apparatus, it is possible to prevent the wavy unevenness and local dents on the effective surface which have conventionally been generated in the mask main body made of a low thermal expansion material such as amber. Also, as shown in FIG.
It is possible to reduce the outward opening of the skirt portion 15 of the mask body 11. As a result, it becomes stronger against the buckling load applied when the skirt is inserted inside the mask frame, the skirt of the mask body can be safely inserted inside the mask frame, and the effective surface is deformed by the buckling load. Can be prevented. As a result, when a shadow mask formed by molding the mask body by the above-mentioned molding device is incorporated into a color picture tube, howling caused by resonance of the shadow mask due to external vibration is less likely to occur, and the characteristics of the color picture tube are improved. You can

[0024]

EFFECT OF THE INVENTION An upper die having a punch having a molding surface composed of a convex curved surface corresponding to the effective surface of the shadow mask and a blank holder provided around the punch, and an effective surface of the shadow mask facing the punch. In a molding apparatus of a shadow mask for a color picture tube, which comprises a knockout having a molding surface made of a corresponding concave curved surface and a blank holder provided around the knockout and having a die facing the blank holder, the blank holder and the die are opposed to each other. If uneven surfaces that engage with each other are provided on the surface, when the blank holder and the die hold the non-hole portion of the peripheral portion of the flat mask at the time of molding, wavy beads are formed on the peripheral portion of the flat mask due to the concave and convex portions. The formation of this bead causes the portion where the effective surface of the flat mask is formed to be pulled in the radial direction. Increases, the effective surface forming portion can be easily sufficiently plastically deformed.

Therefore, when the mask main body is molded by the above-mentioned molding apparatus, it is possible to prevent the wavy unevenness and local dents on the effective surface which have conventionally been generated in the mask main body made of a low thermal expansion material such as amber. It also resists the buckling load applied when the skirt is inserted inside the mask frame, not only can the mask body be safely inserted inside the mask frame, but it also prevents deformation of the effective surface due to the buckling load. it can. As a result, when a shadow mask whose main body is molded by this molding device is incorporated in a color picture tube, howling caused by resonance of the shadow mask due to external vibration is less likely to occur, and the characteristics of the color picture tube are improved. You can

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a shadow mask forming apparatus for a color picture tube that is an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a main part thereof.

FIG. 3 is a view showing a shape of a skirt portion of a mask body formed by the forming apparatus.

FIG. 4 (a) is a diagram showing a configuration of a color picture tube, and FIG. 4 (b) is a diagram showing a configuration of a shadow mask thereof.

FIG. 5 is a diagram showing a configuration of a conventional shadow mask forming apparatus for a color picture tube.

FIG. 6 is a diagram showing a configuration of a main part thereof.

7A and 7B are views for explaining deformation of a mask body molded by a conventional molding apparatus.

FIG. 8 is a diagram showing a shape of a skirt portion of a mask body formed by a conventional forming apparatus.

[Explanation of symbols]

 11 ... Mask main body 13 ... Effective surface 18 ... Punch 21 ... Knockout 24 ... Annular recess 25a ... Inner punch 25b ... Outer punch 26 ... Annular convex 40 ... Blank holder 41 ... Upper mold 42 ... Die 43 ... Lower mold

Claims (1)

[Claims] 1. An upper die having a punch having a molding surface formed of a convex curved surface corresponding to the effective surface of the shadow mask and a blank holder provided around the punch, and an effective surface of the shadow mask facing the punch. In a molding apparatus for a shadow mask for a color picture tube, comprising: a knockout having a molding surface formed of a concave curved surface corresponding to, and a lower die having a die facing the blank holder provided around the knockout. An apparatus for forming a shadow mask for a color picture tube, characterized in that concave and convex portions that engage with each other are provided on the respective facing surfaces.