JPH1167079A - Device and method for molding shadow mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the molding of a mask skirt portion to eliminate distortion after the skirt portion is installed on a mask frame by locating the side wall of a punch inside the outer periphery of a projecting, spherical lower end face, and pressing the molded mask skirt portion with a pressing element toward the side wall, the punch pressing a rectangular, recessed spherical shedder via a planar shadow mask the periphery of which is clamped by a die and a pad. SOLUTION: The peripheral part of the projecting, spherical lower end face 5a of a punch 5 is made to have a smaller diameter than the side face 5b of the punch 5 by a projected step 5c, etc. Also, a pressing element 6 which can move back and forth in the direction of the side wall 5b is placed in a predetermined position of the inner peripheral surface of a die 3 except a corner part. With a shadow mask 1 clamped by the punch 5 and a shedder 2 and depressed, the part of a molded mask skirt portion except its corner is pressed in toward the side wall 5b by the pressing element 6. Therefore, the mask skirt portion is curved from the step 5c, so that the amount of springing-back is reduced and insertion into a mask frame is made easier.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for forming a shadow mask used in a color cathode ray tube.

[0002]

2. Description of the Related Art As shown in FIG. 2, a shadow mask 1 used in a shadow mask type color cathode ray tube is a thin metal plate having a large number of fine electron beam transmitting holes formed in an aligned state, and a central portion formed by a convex spherical surface. A panel in which a skirt portion 1b is further formed around the portion 1a and further inserted into a rectangular frame-shaped mask frame to be integrated, and the shadow mask structure is provided with a phosphor film of three primary colors on its inner surface. The cathode ray tube is accommodated in the cathode ray tube bulb so as to face each other to constitute a color cathode ray tube.

An example of a shadow mask forming apparatus will be described with reference to FIG.

[0004] In the drawing, reference numeral 2 denotes a shedder having a rectangular planar shape and an upper surface formed into a concave spherical shape, which is vertically movably supported.

A die 13 surrounding the shedder 2 supports a peripheral portion of the shadow mask 1 made of a thin metal plate formed with a large number of fine electron beam transmitting holes aligned.

Reference numeral 4 denotes a pad which is disposed above the die 13 and holds the peripheral portion of the shadow mask 1 together with the die 13.

Reference numeral 15 denotes a punch formed into a convex spherical surface 15a aligned with the upper surface of the shedder 2 and inserted into the pad 4 and the die 13 to press the shedder 2 via the shadow mask 1 and move up and down.

The above-mentioned shedder 2, die 13, pad 4 and punch 15 are not shown in the figure, but are heated by heating means.
It is heated to about 0 ° C.

In this apparatus, the periphery of the shadow mask 1 is first firmly sandwiched between the die 13 and the pad 4, and the punch 15 is lowered to form the central portion of the shadow mask 1 into a convex spherical surface. This state is maintained for a certain period of time while heating.

Thereafter, the pad 4 is released, and the punch 15 is further lowered to form a skirt portion 1b on the shadow mask 1.

Thereafter, the punch 15 is raised to release the pad 4 and the die 13, and the shedder is raised to take out the shadow mask 1 having the structure shown in FIG.

[0012]

The above-mentioned shadow mask 3 is fixed to a mask frame and accommodated in a cathode ray tube bulb. An electron beam for emitting a fluorescent film formed on the inner surface of the panel is irradiated with the shadow mask. When hit
Since the shadow mask generates heat and thermally expands, and the light passing through the electron beam shifts in position to cause color shift, recently, a material having a small thermal expansion coefficient, for example, a Fe.Ni-based alloy (trade name: Amber) is used.

However, such a material is inferior in moldability, the mask skirt portion 1b tends to open, and it is difficult to insert the mask skirt portion 1b into the mask frame. However, there is a problem that the workability is extremely poor because the image quality is deteriorated and the image quality is deteriorated.

In order to solve such a problem, Japanese Patent Application Laid-Open No. Sho 62-270225 discloses that a shadow mask is annealed to reduce the yield point strength during warm forming and to provide a high-precision shadow mask without deformation. Is disclosed.

However, it has been desired to further improve the molding state of the mask skirt.

[0016]

SUMMARY OF THE INVENTION The present invention has been proposed for the purpose of solving the above problems, and has a die which surrounds a shedder having a rectangular concave spherical shape and supports a planar mask, and a die above the die. And a pad that sandwiches the peripheral portion of the shadow mask together with the die, and a punch that is inserted into the pad and the die and that presses the shedder through the shadow mask and moves up and down so that the lower end surface has a convex spherical shape. In a shadow mask forming apparatus for forming a skirt on the periphery of a planar shadow mask, the side wall of the punch is positioned inward from the outer periphery of the lower end face, and the mask skirt formed by the punch faces the side wall of the punch. Provided is a shadow mask forming apparatus in which a pressing body that presses and presses is arranged.

Further, the present invention provides a method of forming a shadow mask in which a mask skirt portion is pressed inward while holding the convex spherical portion of a shadow mask having a skirt portion formed around a rectangular convex spherical portion. I do.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A shadow mask forming apparatus according to the present invention is characterized in that a pressing body for pressing a mask skirt portion toward a side wall of a punch is arranged. What is necessary is just to press the part except a corner part.

Further, it is effective to press a position at least 3 mm away from the portion of the mask skirt portion adjacent to the convex spherical surface forming portion.

Further, it is preferable to press the mask skirt so that the difference between the opening diameters at both ends in the axial direction on the outer periphery is within 4 mm.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A shadow mask forming apparatus according to one embodiment of the present invention will be described below with reference to FIG. In the drawing, the same components as those in FIG. 3 are denoted by the same reference numerals, and duplicate description will be omitted.

The device of FIG. 1 differs from the device of FIG. 3 in that the side wall 5 of the punch 5
The diameter of the b portion is set small, and the skirt portion of the shadow mask 1 formed by the punch 5 by projecting and retracting toward the side wall 5b of the punch 5 at the inner peripheral surface position excluding the corner portion of the die 3 The only difference is that the pressing body 6 that presses 1b is arranged.

This apparatus operates in substantially the same manner as the apparatus shown in FIG. 3, except that the shadow mask 1 is sandwiched and pushed down by the punch 5 and the shedder 2 after the convex spherical shape of the shadow mask 1, and held as it is.

At this time, the pressing body 6 includes the side wall 5 b, which is a small diameter portion of the punch 5, and the mask skirt portion 1 of the shadow mask 1.
When the pressing body 6 is protruded, the skirt portion 1b is pushed toward the side wall 5b of the punch 5.

As a result, the skirt portion 1b is bent from the step 5c adjacent to the side wall 5b, which is a small-diameter portion of the punch, and bent from the end of the convex spherical portion 5a of the punch 5 as shown in FIG. As compared with the case, the springback amount can be greatly reduced.

As a result, the shadow mask 1 can be easily inserted into the mask frame, the distortion of the convex spherical surface forming portion 1a can be prevented, and a color cathode ray tube with good image quality can be realized.

The pressing body 6 presses a position 3 mm or more away from the portion of the mask skirt portion 1b adjacent to the convex spherical surface forming portion 1a, so that the influence of the processing in the mask skirt portion 1b affects the shadow mask 1. It is possible not to reach the convex spherical molded portion 1a.

The diameter of the side wall 5b, which is the small diameter portion of the punch 5, and the projecting position and the projecting amount of the pressing body 6 are set so that the springback amount is within 4 mm in consideration of the pushability into the mask frame. do it.

Further, the present invention has been described as a shadow mask forming apparatus. As a forming method, the formed shadow mask 1 is pressed inward on the mask skirt portion 1b while the convex spherical forming portion 1a is protected. Thus, the effect of the present invention can be obtained.

[0030]

As described above, according to the present invention, even when a shadow mask using a material having a large springback amount such as an amber material, the mask is formed while holding the convex spherical molded portion of the shadow mask during molding. Since the skirt portion is pressed inward by the pressing body, the skirt portion can be formed well, there is no distortion after being mounted on the mask frame, and a color cathode ray tube with good image quality can be realized. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a shadow mask forming apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a conventional shadow mask forming apparatus.

FIG. 3 is a perspective view of a general shadow mask.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shadow mask 1a Convex spherical molded part 1b Mask skirt part 2 Shedder 3 Die 4 Pad 5 Punch 5a Convex spherical lower end face 5b Side wall 5c Stepped part 6 Press body

Claims (6)

[Claims] 1. A die that surrounds a rectangular concave spherical spherical shed and supports a planar mask, a pad that is disposed above the die and sandwiches a peripheral portion of the shadow mask together with the die, A shadow mask forming apparatus comprising a punch having a convex spherical surface at a lower end surface which is inserted inside and presses a shedder through a shadow mask to move up and down, and which forms a skirt portion around a flat shadow mask. An apparatus for forming a shadow mask, wherein a pressing body for pressing a mask skirt portion formed by a punch toward a punch side wall is disposed with a side wall of the punch positioned inside an outer periphery of a lower end surface. 2. The shadow mask forming apparatus according to claim 1, wherein a step portion is provided by projecting a peripheral portion of a convex spherical lower end surface portion of said punch. 3. The shadow mask forming apparatus according to claim 1, wherein said pressing member presses a portion of the mask skirt portion other than a corner portion. 4. The shadow mask forming apparatus according to claim 3, wherein a position at least 3 mm away from a portion of the mask skirt portion adjacent to the convex spherical surface forming portion is pressed by a pressing body. 5. The shadow mask according to claim 1, wherein, after the pressing body is released, the mask skirt is pressed by the pressing body so that the difference between the opening diameters at both ends in the axial direction of the outer periphery of the mask skirt is within 4 mm. Molding equipment. 6. A method of forming a shadow mask, comprising: pressing a mask skirt portion inward while holding the convex sphere forming portion of a shadow mask having a skirt portion formed around a rectangular convex spherical portion. .