JPH06131972A - Molding method for shadow mask - Google Patents

Abstract

PURPOSE:To improve the molding precision of an opening section by reducing the curl of the skirt section of a shadow mask. CONSTITUTION:The blank 1a of a shadow mask 1 made of a low-expansion material is inserted between the punch 2 of an upper die and the pad 5 of a lower die, and its outer periphery section is step-molded by step sections 4a, 3a of a wrinkle presser 4 and a die 3. Traction is applied during the machining to arrange an opening section along the punch 2. The traction at the yield point or above of the edge rise section of the outer periphery section of the shadow mask 1 is applied for drawing, then the stepped molding of the outer periphery section is formed into an edge rise section, and the outer periphery section is squeezed to reduce the outward curl.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art CRTs used in recent color televisions are strongly required to be thin and flat and have high brightness. In response to this request, the shadow mask used for the cathode ray tube also has a planar shape and the aperture area is large. Therefore, when the shadow mask is flattened and the aperture area becomes large, local deformation easily occurs due to thermal deformation during image reception. Therefore,
To solve this problem, nickel (N
Low expansion materials containing i) have come into use.

Since this material has a high yield point and poor moldability, it has a drawback in that it is not possible to obtain a satisfactory shape for molding the aperture of the shadow mask and the skirt shape of the peripheral portion. . FIG. 5 shows an example of a conventional molding method.

FIG. 5 is a process diagram showing an example of a shadow mask forming process. In FIG. 5, 1a is a blank of a shadow mask, 2 is a punch as a tool for forming the blank 1a, 3 is an outer tool for forming the blank 1a with a die, 4 is a wrinkle holder for holding the blank, and is attached to the outer periphery of the punch 2. Has been.

Reference numeral 5 is a pad attached to face the punch 2, 6 is a pressure source for applying pressure to the wrinkle retainer 4,
It consists of a spring or a fluid cylinder. Reference numeral 7 is a fluid cylinder that applies pressure to the pad 5.

The molding process of this conventional example is as follows.
As shown in FIG. 5 (a), the blank 1a is placed on the die 3 and then the blank 1a is pressed by the wrinkle retainer 4 and then the blank 1a is formed by the punch 2 as shown in FIG. 5 (b). As shown in FIG. 5 (c), while the blank 1a is sandwiched between the punch 2 and the pad 5, the processing of the blank 1a is completed and the blank 1a is stopped at the bottom dead center.

Next, as shown in FIG. 5 (d), the punch 2 and the wrinkle retainer 4 are raised, and when the wrinkle retainer 4 is raised to a height higher than that of the shadow mask 1, the shadow mask 1 is moved by the pad 5 in the die 3. Complete one cycle by following up. As a result, the shadow mask 1 is created.

[0008]

However, in the conventional molding method described above, as shown in FIG. 5 (d), the low-expansion material shadow mask causes the skirt portion 1c at the outer peripheral portion to curl outward at the same time. There is a problem that the molding accuracy of the opening is poor.

It is an object of the present invention to reduce the curl of the skirt portion of the shadow mask and improve the molding accuracy of the opening portion.

[0010]

SUMMARY OF THE INVENTION According to the present invention, a shadow mask made of a low-expansion material is processed by step forming on an outer peripheral portion thereof, and a tension is applied in the middle of the processing so that an opening portion is formed along a punch. The edge of the outer edge of the outer edge should be stretched over the yield point, and then the stepped molding part of the outer edge should be edged, and at the same time the outer edge should be squeezed to reduce the outward curl. It is characterized by.

[0011]

According to the present invention, when the shadow mask is formed, the outer peripheral portion of the shadow mask is formed, and when the shadow mask is pressed and a gap is provided, the outer peripheral portion of the shadow mask is pressed or a gap is formed, thereby forming an opening. It is possible to form by applying tension to the part. Further, during the edging of the outer peripheral portion of the shadow mask, it is possible to reduce the deformation of the curl shape by pressing the edge again with the wrinkle retainer and pulling the edge. Also, by forming a gap between the wrinkle retainer and the shadow mask, the outer peripheral portion of the shadow mask can be formed as a molded product with less outward curl. Then, the curled shape facing outward can be changed to the deformation facing inward at the stepped molding portion of the wrinkle retainer.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a perspective view of a molded product of the shadow mask 1, FIGS. 2 to 4 are views showing a processing process of a molding method according to an embodiment of the present invention, and FIG. 2 is a molding die showing each process of the first half. 3 and 4 are cross-sectional views of the molding die showing the latter half steps. Here, the respective reference numerals shown in FIGS. 2 to 4 correspond to those in FIG. In this embodiment, the punch 2 is attached to the upper die and the die 3 is attached to the lower die, but the processing timing is the same even in the opposite direction.

As shown in FIG. 2 (a), with the upper and lower molds open, the blank 1a is first placed on the die 3,
As described above, the blank 1a on the die 3 is pressed by the wrinkle retainer 4, and the outer periphery is bent by the stepped portion 4a of the wrinkle retainer 4 and the stepped portion 3a of the die 3.

Next, as shown in FIG. 2 (c), the punch 2 is drawn to a range (1 mm or less) in which the holes of the shadow mask are not deformed, and then wrinkled as shown in FIG. 2 (d). Raise the presser foot 4 up to the height of the stepped portion 3a of the die 3 (gap of 50 to 60% of the edge drawing height of the blank of the shadow mask), and draw-form.
As shown in FIG. 3 (e), when the blank is pressed again by the wrinkle presser 4, the blank is bent to a length H so that the bent portion 1b remains upward by about 2 mm to 10 mm.

Next, as shown in FIG. 3 (f), the wrinkle retainer 4 is used to process the shadow mask while holding it down to H plus α (α is a pulling length such that the shadow mask skirt 1c is almost straight). Then, the opening portion of the shadow mask is pulled, and the molding accuracy easily follows the punch 2.

Next, as shown in FIG. 3 (g), the wrinkle retainer 4 is raised beyond the length of the skirt 1c, and then, as shown in FIG. 3 (h), the drawing process is performed again to reach the bottom dead center. Then, the bent portion 1b of the blank is crushed (the edge height is 2 to 5%), and the skirt 1c is likely to be straight.

Next, as shown in FIG. 4 (i), when the wrinkle retainer 4 and the punch 2 are lifted above the height of the skirt 1c, the mask 1 formed by the pad 5 is lifted to complete one cycle.

[0018]

As described above, according to the shadow mask forming method of the present invention, during the formation of the shadow mask of the low expansion material, the crease retainer is provided and the step forming portion is provided on the outer peripheral portion of the shadow mask of the die to open and close. By doing so, it is possible to apply a tensile force to the shadow mask to improve the molding accuracy of the shadow mask opening portion and reduce the outward curl shape of the outer peripheral portion.

[Brief description of drawings]

FIG. 1 is a perspective view of a shadow mask molded product molded according to the present invention.

FIG. 2 is a diagram showing a processing process of a molding method in an example of the present invention.

FIG. 3 is a diagram showing a processing process of a molding method in an example of the present invention.

FIG. 4 is a diagram showing a processing process of a molding method in an example of the present invention.

FIG. 5 is a diagram showing a processing process showing an example of a conventional shadow mask molding process.

[Explanation of symbols]

1 ... Molded shadow mask, 1a ... Blank, 1b
... Blank bent portion, 1c ... Shadow mask skirt, 2 ... Punch, 3 ... Die, 3a ... Die step portion, 4 ... Wrinkle retainer, 4a ... Wrinkle retainer step portion,
5 ... Pad, 6 ... Spring or fluid cylinder, 7 ... Fluid cylinder.

Claims (1)

[Claims] 1. A shadow mask blank having a step on the outer peripheral portion of the blank of the shadow mask, the step having an upward direction opposite to the forming direction, a wrinkle retainer facing the die, and the blank of the shadow mask by the wrinkle retainer. In the molding method of pressing the outer peripheral portion of the shadow mask and sandwiching it with a punch and a pad to mold it into a desired shape, and drawing the outer peripheral shape of the shadow mask with the punch and the die. The blank of the shadow mask is formed by forming a gap between the wrinkle retainer and the die by making a gap required for the reduction with respect to the edge drawing height of the blank of the shadow mask, and lowering the wrinkle retainer again. When pressing, the outer peripheral portion of the blank of the shadow mask is shaped so that a bent portion of a required length remains on the side surface of the step of the die, and then the wrinkle pressing and the Pressing the outer peripheral portion of the blank of the shadow mask in Lee,
The aperture of the shadow mask is clamped by the punch and the pad, and the aperture / outer peripheral portion is squeezed again to apply tension above the yield point to squeeze the edge height of the shadow mask. Squeezing is performed at a sufficient height, the wrinkle retainer is opened upward again, and the punch and the pad are sandwiched between the punch and the pad at the same time with a gap that does not press the outer peripheral portion of the blank of the shadow mask. A method for forming a shadow mask, wherein the shadow mask is formed while squeezing the inwardly bent shape left on the outer peripheral portion of the blank.