JPH043054B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a shadow mask forming apparatus for a color cathode ray tube that presses and molds a shadow mask to be fitted inside a panel of a color cathode ray tube.

[Technical background of the invention]

As shown in FIG. 1, a conventional color cathode ray tube shadow mask forming apparatus includes a die 1, a blank holder 3 having a wrinkle presser bead 2, a punch 4, and a knockout 5.
As shown in Figure a, a portion 7 of the shadow mask material 6 that will become the mask skirt is clamped by the die 1 and the blank holder 3, and then a punch 4 is inserted between this and the knockout 5 as shown in Figure 1b. extrude it into the die 1 until it squeezes the shadow mask material 6,
The spherical portion 8 is stretched out, and at this time the movement of the mask skirt portion 7 is restricted by the wrinkle holding bead 2, and then the die 1 and the blank holder 3 are bonded together as shown in FIG. 1c. The clamping pressure is released, the punch 4 is further pushed out onto the drawing surface 9 of the die 1, and the portion 7 that will become the mask skirt is drawn.

[Problems with background technology]

Although various materials are used for such a shadow mask material 6, hard materials such as amber materials are particularly difficult to mold, and therefore problems tend to occur in molded products using the conventional apparatus described above. For example, as shown in FIG. 2, the skirt edge 12 of the mask skirt 11 curves outward due to spring back, which causes a part of the effective spherical surface 13 to become depressed, resulting in a dropped edge 14. be. The reason why the spring back occurs outward is that the portion of the mask skirt 11 that will become the skirt edge 12 is bent outward in advance with respect to the spherical surface 13 by the wrinkle presser bead 2. .

[Purpose of the invention]

The present invention, in such a color cathode ray tube shadow mask forming apparatus, eliminates the crease presser bead that was conventionally provided in the die and blank holder that clamps the portion of the shadow mask material that becomes the mask skirt, and replaces this with the crease presser bead that was conventionally provided in the blank holder. It is an object of the present invention to provide an effective means for directing the spring back of the skirt edge inward.

[Summary of the invention]

The configuration of the color cathode ray tube shadow mask forming apparatus of the present invention includes a die, a blank holder that clamps the mask skirt of the shadow mask material together with the die, and a blank holder that is moved from the inner surface of the blank holder to the aperture surface of the die. A punch that stretches the spherical part of the shadow mask material with a convex surface and draws the part that will become the mask skirt, and the convex surface of this punch and the spherical part of the shadow mask material are squeezed with a concave surface, and after the forming is completed. and a knock-out for extruding the shadow mask from the die, the apparatus further comprising: a protrusion provided on the lower end edge of the inner surface of the blank holder and fitting into the recess; The convex part is formed by pressing the part that will become the mask skirt between vertically opposing surfaces and vertically opposing surfaces to form two clamps that bend the part that will become the skirt edge inward before drawing with the punch. A shadow mask forming device for color cathode ray tubes, each having a pressure surface,
Then, before drawing the part that will become the mask skirt, the part that will become the skirt edge is bent inward by the concave and convex parts, thereby reducing the spring back of the skirt edge after forming. It is meant to face inward.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail with reference to the embodiments shown in FIGS. 3 to 5.

As shown in FIGS. 3 and 4, the lower mold substrate 2
A plurality of guide pins 23 are integrally provided to protrude from a support 22 fixed to the upper surface of the die 24, and a die 24 is movable up and down via a guide bush 25 integrally fitted to the die 24. A plurality of lower die dictation pins 26 are fitted into the lower die substrate 21 so as to be movable up and down, and are elastically projected upward by elastic urging means such as a spring or air pressure. A push-up plate 27 is integrally provided at the upper end, and the push-up plate 27 pushes up the die 24 and the knockout 29 fitted to the drawing surface 28 of the die 24 so as to be movable up and down. A plurality of stepped bolts 30 screwed onto the support base 22 lock the die 24 from being pushed up at the position shown in FIG.

In addition, a plurality of guide pins 3 are provided on the lower surface of the upper mold board 31.
A blank holder 33 and a plate 34 integral with this blank holder 33 are attached to this guide pin 32, and a plate 34 is attached to this blank holder 3.
3 and the plate 34 through a guide bushing 35 integrally fitted thereto, and is fitted to the upper mold base plate 31 so as to be vertically movable, and is supported by resilient biasing means such as a spring or air pressure. A plurality of upper die duction pins 36 elastically protrude downward.
, the blank holder 33 is pushed down through the plate 34, and the upper die substrate 3 is pressed down.
1, the blank holder 33 is held in place via the plate 34 at the position shown in FIG. Further, a punch 38 is fixed to the lower surface of the upper die substrate 31, and the punch 38 is moved from the blank holder 33 to the die 24.
It is inserted over the entire length.

Further, a plurality of stopper fitting holes 39 are formed from the upper surface to the lower surface of the die 24, and a lower stopper 40 that projects upward from the support base 22 is fitted into the stopper fitting holes 39 so as to be vertically movable. At the same time, the upper stopper 41 protruding downward from the blank holder 33 is fitted so as to be vertically movable.

Further, as shown in FIG. 5, a concave portion 44 is provided by cutting out the upper edge of the aperture surface 28 of the die 24, and a convex portion 45 that fits into the concave portion 44 is provided on the lower edge of the inner surface of the blank holder 33. Provided in one piece.

Next, to explain the operation of this embodiment, by pulling up the upper mold substrate 31, the blank holder 33 and the punch 38 located on the upper side are separated from the die 24 and the knockout 29 located on the lower side, and during this time A shadow mask material 51 is inserted into. By further pushing down the upper mold board 31,
As shown in FIG. 5a, when the portion 52 of the shadow mask material 51 that will become the mask skirt is clamped by the die 24 and the blank holder 33 with the die cutting pressure of the die cutting pins 26 and 36, this mask skirt is formed. The part 53 which becomes the skirt edge of the part 52 that becomes
4 and the convex portion 45 of the blank holder 33 to form an inward edge. The concave portion 44 of this die 24 and the convex portion 4 of the blank holder 33
5, the portion 52 that will become the mask skirt is clamped by two clamping surfaces, one that faces vertically and the other that faces vertically, so that the portion 53 that will become the skirt edge is curved. . At this time, the dimension l ₁ of this bent portion 53 should not be larger than the dimension l ₂ of the remaining sandwiched portion of the mask skirt 52.

By further pushing down the upper die board 31, the punch 38 is lowered while contracting the upper die dictation pin 36 with respect to the blank holder 33 which is locked in place by the stoppers 40 and 41.
As shown in FIG. b, the punch 38 is pressed from the inside of the blank holder 33 by the convex surface of the punch 38 and the concave surface of the knockout 29 until the spherical portion 54 of the shadow mask material 51 is pressed against the drawing surface of the die 24. 28, and the portion 54 that becomes the spherical surface is stretched out. Note that until the overhanging process shown in Fig. 5b, the dictation pin 2
Since the clamping pressure from 6 and 36 is effectively acting on the die 24 and the blank holder 33, the portion 52 which becomes the mask skirt is clamped by the die 24 and the blank holder 33.

By further pushing down the upper die substrate 31, the knockout 29 that clamps the spherical portion 54 together with the punch 38 is pushed down, and when the knockout 29 protrudes below the lower surface of the die 24, the push-up plate 27 is pushed down. away from the bottom surface of the die 24,
The die 24 descends to the upper surface of the support base 22, albeit slightly. At this time, since the blank holder 33 is locked in place by the stoppers 40 and 41, the die 24 and the blank holder 33 are separated from each other, as shown in FIG. The part 52 that becomes the skirt is completely released, and in this state of releasing the clamping pressure, the punch 38 is inserted into the die 2.
The portion 52 that is further extruded to the drawing surface 28 of No. 4 and becomes the mask skirt is drawn to the bottom of the recess 44 .

Finally, when the drawing process is completed as shown in FIG. The knockout 29 is raised to extrude the formed shadow mask 55 from the drawing surface 28 of the die 24.

〔Effect of the invention〕

According to the present invention, a recess is provided on the upper end edge of the aperture surface of the die, and a protrusion that fits into the recess is provided on the lower end edge of the inner surface of the blank holder, and the recess of the die and the protrusion of the blank holder are provided. The mask skirt part of the shadow mask material is squeezed between vertically opposing surfaces and vertically opposing surfaces to form two clamping surfaces that curve the skirt edge inward before drawing with a punch. Therefore, it is possible to add an edge in the opposite direction to the conventional wrinkle presser bead to the part that becomes the skirt edge, and direct the spring back of this skirt edge inward, thereby eliminating the conventional spring back that occurs when facing outward. It is possible to effectively prevent edge drop (indentation) on the effective spherical surface due to the influence of.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the molding process using a conventional shadow mask mold, Figure 2 is a cross-sectional view of a shadow mask molded using the conventional mold, and Figure 3 is a cross-sectional view of a shadow mask molded using the conventional mold.
The figure is a cross-sectional view showing one embodiment of the color cathode ray tube shadow mask molding apparatus of the present invention during molding, FIG. 4 is a cross-sectional view when the molding is completed, and FIG. 5 is a cross-sectional view of the main parts showing the molding process. be. 24...Die, 28...Aperture surface, 29...Knockout, 33...Blank holder, 38...Punch, 44...Concave portion, 45...Convex portion, 51...Shadow mask material, 52...Mask skirt and Part that becomes the skirt edge, 53... Part that becomes the skirt edge, 54...
... Spherical part, 55... Molded shadow mask.

Claims (1)

[Claims] 1. A die, a blank holder that clamps together with the die a portion of the shadow mask material that will become the mask skirt, and a blank holder that moves from the inner surface of the blank holder to the aperture surface of the die to engage the spherical surface of the shadow mask material. A punch that uses a convex surface to overhang the part that will become the mask skirt and draws the part that will become the mask skirt, and a punch that presses the spherical part of the shadow mask material with a concave surface together with the convex surface of this punch, and then presses the shadow mask after completion of molding into the die. A device equipped with a knock-out for extruding the blank, comprising: a recess provided on the upper edge of the aperture surface of the die; and a convex portion provided on the lower edge of the inner surface of the blank holder and fitting into the recess; The concave portion of the die and the convex portion of the blank holder are formed by pressing the portion that will become the mask skirt between vertically opposing surfaces and vertically opposing surfaces to form the portion that will become the skirt edge before drawing with the punch. A shadow mask molding device for a color cathode ray tube, characterized in that each of the two clamping pressure surfaces curves inward.