JPH10291035A - Forming device for shadow mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize a spring back quantity as well as deformation by effectively utilizing mechanical properties of a metallic material. SOLUTION: A punch 1 and a shadder 3 arranged to a shadow mask forming device are respectively divided into three parts of a center part 1c (3a), a peripheral parts 1d (3b) by a heat insulation material 20, each heating temp is individually set. By setting a heating temp. of each center part 1c (3a) of the punch 1 and the shedder 3 at 10-30 deg.C lower than a heating temp. of each peripheral part 1d(3b), a spring back quantity is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for forming a shadow mask, and more particularly to an apparatus for forming a shadow mask in which a central portion and a peripheral portion of a punch and a shedder have different heating temperatures.

[0002]

2. Description of the Related Art In general, a shadow mask for a color cathode ray tube is formed by forming a thin flat plate of a shadow mask material plate in which slit-shaped or round electron beam passage holes having a size of a micron unit are perforated in a predetermined arrangement. Is fixed to a glass panel and has an important function of correctly irradiating the phosphor with an electron beam emitted from an electron gun.

[0003] On the inner surface of the glass panel, red, green and blue phosphors are exposed and arranged at positions corresponding to the electron beam passage holes. If the relative position between the phosphor and the electron beam shifts, the electron beam emitted from the electron gun and passing through the electron beam passage hole of the shadow mask cannot reach a predetermined phosphor, causing color shift and color bleeding. Or

[0004] One of the factors causing the displacement between the electron beam passage hole and the phosphor is a thermal expansion deformation of the shadow mask called doming. As a countermeasure to reduce this doming, iron /
Nickel-based Invar alloy materials have been used as shadow mask materials.

A description will be given of a conventional shadow mask forming apparatus and a forming order using the Invar alloy material.
FIG. 3 is a sectional view of a main part of a conventional shadow mask forming apparatus. As shown in the figure, a state in which a shadow mask material plate is placed on a shadow mask forming apparatus is shown. In order to form the curved surface of the shadow mask as an upper mold, this molding apparatus aims at the curved surface of the shadow mask blank 8 in consideration of the springback of the shadow mask material plate 8 and the outer peripheral shape and the final shape. A punch 1 having a side wall 1b for forming a skirt portion, and a punch 1
And a pad 2 having a clamp surface 2a and a clamp groove 2b. Further, the lower die is disposed so as to face the punch 1, and the upper surface has a curved surface portion 1 a of the punch 1.
And a die 4 having a clamp surface 4c and a bead 4b which are arranged on the outer periphery of the shedder 3 so as to face the pad 2 and which hold the periphery of the shadow mask blank 8 together with the pad 2. It is composed of

The punch 1 and the pad 2 are respectively fixed to an inner rod 5 and an outer rod 6 of the molding apparatus, and the shedder 3 is lifted upward by a die cushion rod 7 of the molding apparatus. Further, the die 4 partially rides around the shedder 3 and moves up and down as the shedder 3 goes up and down. When molding a shadow mask of an Invar alloy material using a molding device having such a structure, since the amount of springback is large in molding at room temperature,
Although not shown, the punch 1, the pad 2, the shedder 3, and the die 4, which are portions that come into contact with the shadow mask material plate 8, are generally heated to about 200 ° C. by a heating device to be formed. As shown in FIG. 4, the mechanical properties of the metal material are such that the 0.2% proof stress decreases as the temperature increases. In order to reduce the amount of springback by utilizing this property, molding is performed after maintaining the specified temperature by the heating device as described above.

Referring to FIG. 3, a process of forming the shadow mask 18 from the shadow mask blank 8 will be schematically described. The shadow mask material plate 8 placed at a predetermined position on the die 4, which is the lower mold of the shadow mask forming apparatus,
In the pressing step of forming the planned skirt portion 8a, the pad 2 descends, and the clamp surface 2a, the clamp groove 2b of the pad 2, the clamp surface 4c of the die 4, and the bead 4b form the planned skirt portion of the shadow mask material plate 8. 8a is fixed.

In the curved surface forming step, the punch 1 descends and comes into contact with the previously placed shadow mask material plate 8 to start the curved surface forming, and the punch is placed on the upper surface of the shedder 3 via the shadow mask material plate 8. The overhang is carried out until 1 comes into contact, and a curved surface portion of the shadow mask and an annular curved bead are formed.

When the punch 1 comes into contact with the shedder 3 and starts descending in the scheduled skirt isolation step, the die 4 also descends accordingly, but the pad 2 stops descending by a stopper (not shown). A gap is formed between the shadow mask blank 2 and the peripheral portion of the shadow mask blank 8 to be released.

In the skirt forming step, the punch 1 continues to descend even after the die 4 reaches the lowest point, and is bent between the inner wall 4a of the die 4 and the side wall 1b of the punch 1 to form a skirt 18a (not shown). ) Is formed. That is, in this step, the skirt portion 1 is removed from the shadow mask blank 8.
The prototype of the shadow mask 18 having 8a is completed.

Further, the punch 1 reaches the lowest point, and the state is maintained for several seconds. Next, the punch 1 starts to rise.
At this time, the shadow mask 18 rises with the rise of the punch 1, and the end surface of the skirt portion 18 a contacts the clamp surface 2 a of the pad 2. The shadow mask 18 stops in this state, but the punch 1 keeps rising further, so that the shadow mask 18 and the punch 1 are completely separated. This operation is called knockout. The subsequent steps are omitted.

As shown in FIG. 5, even when the above-described molding apparatus is used, the folded skirt portion 18a of the shadow mask 18 made of an Invar alloy material can be used.
Springback effect works due to the properties of metal materials.
May occur. As a countermeasure for suppressing the springback amount, the shadow mask material plate 8 is annealed and then transferred to a forming process. In the shadow mask forming process, the punch 1 and the pad 2 which are portions that come into contact with the shadow mask material plate 8 are used. , The shedder 3 and the die 4 are maintained at about 200 ° C. by a heating device and then subjected to warm molding.

[0013]

However, in the shadow mask forming apparatus as described above, each of the portions that come into contact with the shadow mask material plate 8, for example, the punch 1, the pad 2, the shedder 3, and the die 4 are all of a predetermined shape. About 20 of temperature
Molding is performed under substantially uniform temperature conditions at 0 ° C.
As described above, in the shadow mask formed under the uniform temperature condition, springback may remain, and due to the effect of the springback, the skirt portion expands, and a thick film is formed even in the effective area of the shadow mask. There is a problem that the curved surface of the shadow mask cannot be obtained, and a dense dot (stripe) arrangement cannot be obtained at the time of exposure. In view of the above, the present invention has been proposed in view of the above problems, and has as its object to effectively utilize the mechanical properties of a metal material and minimize the amount of springback to minimize deformation. It is an object of the present invention to provide a shadow mask forming apparatus which enables the above.

[0014]

SUMMARY OF THE INVENTION The present invention has been proposed for the purpose of solving the above-mentioned problems, and has a die for holding a shadow mask material plate, a pad for pressing a peripheral portion of the material plate, and a pad. A shadow mask including a punch that slides on an inner wall of a die to form a predetermined curved surface portion and a skirt portion on a material plate, a shedder disposed opposite to the punch, and a pad, a die, a punch, and heating means for the shedder. The heating means provides a shadow mask forming apparatus in which the faces facing the punch and the shedder are paired and the heating temperatures of the central portion and the peripheral portion are different.

Further, the present invention provides a shadow mask forming apparatus in which the heating temperature of the periphery of the punch and the shedder is the same as the heating temperature of the pad and the die.

The different heating temperatures of the central part and the peripheral part of the punch and the shedder can be set differently by the thermal separation between the central part and the peripheral part of the punch and the shedder. A molding device is provided.

Further, the present invention provides a shadow mask forming apparatus in which the heating temperature of each central portion of the punch and the shedder is lower by 10 to 30 ° C. than the heating temperature of each peripheral portion.

Further, the present invention provides a shadow mask forming apparatus in which a heating means for a punch, a pad, a shedder and a die uses both a heating medium oil circulation system and a heater heating system.

Further, the thermal separation provides an apparatus for forming a shadow mask in which a heat insulating material sandwiching the punch and the shedder is interposed between the central part and the peripheral part.

Further, the present invention provides an apparatus for forming a shadow mask in which the shadow mask material plate is an iron / nickel-based Invar alloy material.

[0021]

Embodiments of the present invention will be described with reference to the drawings. 1 to 2, reference numeral 1 denotes a punch, 1c denotes a central portion of the punch, 1d denotes a peripheral portion of the punch, 2 denotes a pad, 3 denotes a shedder, 3a denotes a central portion of the shedder, 3b denotes a peripheral portion of the shedder, and 4 denotes a die. , 8 is a shadow mask material plate, 8a is a planned skirt, 9 is wrinkles, 18
Is a shadow mask, 18a is a skirt portion, and 20 is a heat insulating material. The basic operation of the shadow mask forming apparatus is the same as that of the prior art, so that the description is omitted, and the heating means for the central portion and the peripheral portion will be described with the opposing surfaces of the punch and the shedder being the main subject of the present invention. .

FIG. 1 is a sectional view of a main part of a shadow mask forming apparatus according to the present invention. The difference from the prior art is that the heating temperature of each part can be set individually by thermal separation between the central part and the peripheral part of the punch 1 and the shedder 3 which are arranged to face each other. For example, as a thermal separating means, a heat insulating material 20 is interposed between the central portion and the peripheral portion of the punch 1 and the shedder 3 so as to be sandwiched, and the central portion and the peripheral portion are divided into three. That is, the punch 1 is located at the center 1
c, a heat insulating material 20 arranged on both sides of the central portion 1c, and a peripheral portion 1d arranged on both sides so as to sandwich the heat insulating material 20. Similarly, shedder 3
a, a heat insulating material 20 disposed on both sides of the central portion 3a, and a peripheral portion 3b disposed on both sides so as to sandwich the heat insulating material 20.

With the above-described structure, the punch 1 and the shedder 3 can be respectively
The central portion 1c (3a) and the peripheral portion 1d (3b) are separated from each other and thermally separated. Therefore, the punch 1 and the shedder 3 are composed of the central portion 1c (3a) and the peripheral portion 1d (3d).
It becomes possible to set the desired temperature individually by setting the heating temperature to be different from that in b).

The reason for the above-mentioned structure is to make effective use of the 0.2% proof stress, which is the mechanical property of the metal material. In particular, it is effective in the step of forming the shadow mask 18 using an iron / nickel-based Invar alloy material. It is more advantageous in terms of the amount of springback that the shadow mask material plate 18a is formed with different mold temperatures in contact with the central part and the peripheral part of the shadow mask material plate 18a. Specifically, in the shadow mask forming apparatus, the punch 1 contacting the shadow mask material plate 18a.
Central part 1c, peripheral part 1d and central part 3 of shedder 3
By setting the heating temperature separately for the edge portion a and the peripheral portion 3b, a temperature difference between the central portion and the peripheral portion of the shadow mask material plate 18a is obtained. Here, the heating temperature of the central portion of the shadow mask material plate 18a is set to be lower than the heating temperature of the peripheral portion. The heating temperature of the central portion 1c (3a) and the peripheral portion 1d (3b) of the punch 1 and the shedder 3 are the same.

Each peripheral portion 1 of the punch 1 and the shedder 3
The heating temperature of d (3b) is the same as the heating temperature of the pad 2 and the die 4 because the skirt portion 18a is formed by bending the expected skirt portion 8a. The setting of the heating temperature differs depending on various conditions, but the pad 2, the die 4, the punch 1 and the peripheral edge 1d (3b) of the shedder 3
Heating temperature is the same temperature, generally 180-230 ° C
Is set to

As described above, the punches 1 arranged opposite to each other
And the shedder 3 with the heat insulating material 20 interposed therebetween so that each central portion 1c (3a) and each peripheral portion 1d (3
b) As a means for effectively using the inclined portion having a 0.2% proof stress, which is a mechanical property of the metal material, by dividing into 3), each central portion 1c (3a) of the punch 1 and the shedder 3
Heating temperature of each peripheral part 1d (3b) by 10
It is characterized in that it is set to be lower by 30 ° C.

As means for controlling the heating of the punch 1, the pad 2, the shedder 3 and the die 4, either a heating medium oil circulation system or a heater heating system is employed.
The present invention employs both of them in combination. In general, the heat medium oil circulation system is excellent in heat retention, and the heater heating system is excellent in rapid temperature control and temperature controllability. By using both of them together, the characteristics of both are maximized. This makes it possible to control the heating temperature with high precision.

[0028]

As described above, according to the shadow mask forming apparatus of the present invention, by forming a heating temperature difference between the central portion and the peripheral portion of the shadow mask material plate at the time of forming the shadow mask, the metal characteristic can be reduced. It is possible to form a curved surface and a skirt under conditions that maximize the characteristics of a certain 0.2% proof stress (yield point). That is, in the shadow mask processed by this molding apparatus, the amount of springback at the central portion, the peripheral portion, and the skirt portion of the formed shadow mask is suppressed, and a predetermined shadow mask curved surface is obtained. Dot (stripe) arrangement can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a shadow mask forming apparatus according to the present invention.

FIG. 2 is a sectional view of a main part showing a pressed state in FIG. 1;

FIG. 3 is a sectional view of a main part of a conventional shadow mask forming apparatus.

FIG. 4 is an explanatory view showing mechanical properties of a metal material.

FIG. 5 is a perspective view of a shadow mask.

[Explanation of symbols]

 Reference Signs List 1 punch 1c central part of punch 1d peripheral part of punch 2 pad 3 shedder 3a central part of shedder 3b peripheral part of shedder 4 die 8 shadow mask material plate 8a scheduled skirt part 18 shadow mask 18a skirt part 20 heat insulating material

Claims (7)

[Claims] A die for holding a shadow mask material plate;
A pad that presses a peripheral portion of the material plate, a punch that slides on an inner wall of the die and the pad to form a predetermined curved surface portion and a skirt portion on the material plate, and a shedder arranged to face the punch. In a shadow mask forming apparatus including a heating means for the pad, the die, the punch and the shedder, the heating means comprises a pair of surfaces facing the punch and the shedder, and a heating temperature for each central part and a peripheral part. A shadow mask forming apparatus characterized in that 2. The shadow mask forming apparatus according to claim 1, wherein the heating temperature of the periphery of the punch and the shedder is the same as the heating temperature of the pad and the die. 3. The heating temperature at the central portion and the peripheral portion of the punch and the shedder which are different from each other can be set individually by the thermal separation between the central portion and the peripheral portion of the punch and the shedder. The shadow mask forming apparatus according to claim 1, wherein: 4. The shadow mask forming apparatus according to claim 1, wherein the heating temperature of each central part of the punch and the shedder is lower by 10 to 30 ° C. than the heating temperature of each peripheral part. 5. A shadow mask forming apparatus according to claim 1, wherein the heating means for the punch, pad, shedder and die employs both a heating oil circulation system and a heater heating system. 6. A shadow mask forming apparatus according to claim 3, wherein said thermal separation is provided with a heat insulating material sandwiching said punch and said shedder between said central portion and said peripheral portion. 7. The shadow mask forming apparatus according to claim 1, wherein said shadow mask material plate is an iron / nickel-based Invar alloy material.