JPH01289515A - Forming apparatus for shadow mask - Google Patents

Abstract

PURPOSE:To enable forming the shadow mask having high strength and generat ing no local deformation of hole shapes by constituting pad level differences to be different in each part according to sorts of transmission holes bored on the blank shadow mask plate. CONSTITUTION:An outer peripheral edge 31 of the pad is positioned at least under the equal level to inner peripheral edge 41 of the die. As for the distance H in the height direction between the inner peripheral edge 41 of the die and the outer peripheral edge 31 of the pad 3, when the blank shadow mask plate having round transmission hole is formed, the value H is minimized at the corner part or in its vicinity. Further, when forming the blank shadow mask having a slot shaped transmission hole, the value H is maximized at the center part of the side directing the same transversal direction of the slot or at its vicinity. By this method, the deformation and break of the transmission hole are prevented, an uniform state of spherical surface is maintained and the high strength is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shadow mask forming apparatus for forming a shadow mask for a color cathode ray tube.

[Conventional technology]

The color cathode ray tube's shadow mask is fixed within the glass panel and has the function of determining the correspondence between the electron beam emitted from the electron gun and the phosphor.

A large number of slot-shaped holes shown in FIG. 10(a) and round-shaped holes shown in FIG. This shadow mask material plate is given a predetermined spherical shape by press molding.

As shown in FIG. 11, a shadow mask forming apparatus generally includes a bunch 1 having a spherical part on the upper part that takes into account springback of the material and a side wall part that determines the outer circumferential shape for forming a shadow mask spherical surface, and a bunch 1. A blank holder 2 is disposed on the outside of the pad 3, and a pad 3 located on the outside of the pad 3 whose part or peripheral part of the surface facing the bunch 1 is the same as the spherical part of the bunch 1 is disposed at the bottom. It consists of four main points: a die 4 which is placed opposite the blank holder 2 and which fixes the shadow mask material plate together with the blank holder 2.

Further, the blank holder 2 and the die 4 are provided with a bead portion or a stepped portion in order to increase the clamping force to the glossy mask material plate.

The shape of the spherical part of the bunch 1 is generally expressed by a mathematical formula, and a part of the surface of the blank holder 2 facing the die 4 has a spherical part expressed by the same mathematical formula as the bunch 1 or a function formula continuous with the spherical part of the bunch 1. Or lay down in the whole area. 7 are provided.

Furthermore, a spherical surface similar to the blanker holder 2 is provided on the surface of the die 4 facing the blank holder 2 .

Therefore, the outer peripheries of the bunch 1 and the band 3 and the inner peripheries of the blank holder 2 and die 4 have substantially the same shape.

Next, the operation will be explained. As shown in FIG.

As soon as the peripheral portion of the shadow mask material plate 5 which has been formed on the lower mold is first fixed by the blank holder 2 and the die 4, the bunch 1 is lowered and the shadow mask material plate 5 is fixed as shown in FIG. 13. At this time, spherical extension is started, and extension processing is performed until the bunch 1 comes into contact with the upper surface of the pad 3, and a spherical part is formed on the shadow mask material plate 5.

The pad 3 is positioned in advance with a difference in level from the die 4, in order to improve the processing efficiency.

Next, as shown in Fig. 14, when the pliers 1 and the pliers 1 come into contact with the pad 3 and start crushing, the die 4 is also aligned, but the blank holder 2 is attached to the hide gauge (not shown). Since the die 4 and the blank holder 2 are fixed, a gap is created between the die 4 and the blank holder 2, and the fixation of the peripheral portion of the shadow mask material plate 5 is released.

Next, as shown in FIG. 15, even after die 4 reaches its lowest point, bunch L and pad 3 continue to descend, and at that time, a shadow mask is formed between the side walls of die 4 and bunch 1. The skirt portion is molded.

After each of the four points reaches the lowest point, this state is maintained for several seconds, and then the bunch 1, blank holder 2, band 3, and die 4 move upward to obtain a molded shadow mask.

The outline of the shadow mask is G, as shown in Part 16.
It has a rectangular shape. When the shadow mask material plate 5, which is a flat plate, is spherically extended with this rectangular shape, the degree of machining of the diagonal axes L D and h, which are longer distances among the axes passing through the center of the shadow mask material plate 5, is large, and the distance short Y axis LY
The degree of machining on the top becomes smaller.

As mentioned above, the pad 3 is positioned below the die 4 with a step to improve the processing efficiency of the spherical surface of the shadow mask. Since the edges have almost the same shape 2, the machining rate is uniform around the entire circumference.In order to increase the machining rate, increasing the step between the pad 3 and the die 4 increases the machining rate on the diagonal axis. The tensile strength of the shadow mask material plate 5 is exceeded, and the first
As shown in Fig. 7fa), a break 5b occurs in the mask hole 5a, and even within a stress that is less than the tensile strength, local deformation 5c of the mask hole 5a occurs as shown in Fig. 17 fa). Resulting in.

Such deformation of the mask hole 5a is also reflected when applying the phosphor, and as shown in FIG. 18, the 8M holes 5d may be connected, or phosphors of different colors may overlap, resulting in white stains on the screen. Furthermore, when the CRT is operated, it emits an unspecified color, leading to a decrease in purity.

In order to prevent such deformation of the mask hole 5a, the height difference between the die 4 and the pad 3 can be reduced, but this will reduce the degree of processing in other parts and cause some plastic deformation on the spherical surface of the shadow mask. If the processing does not proceed until the point where the material is elastically deformed and is removed from the forming equipment, the spherical surface may have poor tension as shown by the solid line in Figure 19, or if the yield point material is processed near the yield point, As a result, stretcher strain occurs.

Problems to be Solved by the Invention] Since the conventional shadow mask forming apparatus is configured as described above, the degree of processing when extending the spherical surface of the shadow mask remains uneven at various parts on the spherical surface of the shadow mask, resulting in a compromise. It is necessary to sufficiently adjust the mold to meet these conditions.

Further, even after molding, there were problems such as the tension being weak in areas where the degree of processing was insufficient on the spherical surface of the shadow mask, resulting in deformation and vibration.

This invention was made to solve the above-mentioned problems, and it is possible to adjust the degree of processing on the spherical surface of the shadow mask, and to form a shadow mask that is strong and does not cause local hole shape deformation. The purpose of this invention is to obtain a shadow mask forming device that can be used.

(Means for Solving the Problems) The shadow mask forming apparatus according to the present invention differs from the shape of the outer periphery of the punch and pad and the shape of the inner periphery of the blank holder and die, and the step between the pad and the die is made into a round shape. When molding on a spherical surface of a shadow mask having transmission holes, the minimum value should be set in the vicinity of the cope, and when molding a shadow mask material plate with slot-shaped transmission holes, the shortness of the slot should be minimized. The maximum value is obtained near the center of the side parallel to the hand direction.

[For production]

In the case where the outer circumferential shape of the punch and band and the inner circumferential shape of the blank holder and die in this invention are different, and the step between the pad and the die is a round transparent hole, it is minimized in the vicinity including the corner, and the slot-shaped For +3 round holes, the maximum value occurs near the center of the side parallel to the transverse direction of the slot, so in the spherical expansion process of gloss mask molding, the X axis.

The difference in strain in the Y-axis and Z-axis directions is reduced, giving equal or close to the same strain at all locations.
This reduces the difference in the degree of processing in some parts, and sufficiently plasticizes the entire shadow mask.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
In the figure, 4 is a die of the shadow mask molding device, which is indicated by a solid line. 3 is a pad, which is indicated by a dotted line. Reference numeral 41 indicates the shape of the inner peripheral edge of the die 4, which is indicated by a solid line. 31 forms the outer peripheral edge shape of the pad and is shown by a dotted line.

The outer circumferential edge shape 31 of the pad 3 and the inner circumferential edge shape 41 of the die 4 have different shapes, and their cross-sectional shapes are taken along the X-axis, Y-axis, diagonal axis, and Z-axis as shown in FIG. 2. Shown below.

FIG. 2(a) is an X-axis sectional view, FIG. 2(b) is a Y-axis sectional view, and FIG. 2(C) is a part of a diagonal-axis sectional view. The outer periphery 31 of the band 3 and the inner periphery of the die 4 in the figure! ! The height H in the Z-axis direction of 41 is called a band step.

In the shadow mask forming apparatus of the prior art, this band height difference H is almost the same all around the circumference, but in the present invention, the band height difference H is configured to be different in each part depending on the type of transparent hole formed in the shadow mask material. ing.

This example relates to a method of forming a shadow mask material plate having round transparent holes, and the bad step H is the upper step on the X axis as H, the upper step on the Y axis as HV, and the step on the diagonal axis (corner part). The structure is such that when Ho is HX, Hy > H.

The circumferential shapes of the punch facing the pad 3 and the blank holder facing the die are also processed to have the same shape as the respective opposing parts.

Next, the procedure of molding using this shadow mask molding apparatus will be explained step by step. Below, Figure 3 (a) - Figure 6 (a)
) is a cross section on the X axis, and Figures 3(b) to 6(b) are 'l
4',, liJ top cross section Figures 3 (C) to 6 (C) show cross sections on the diagonal axis.

As shown in FIGS. 3(a) to 3(C), the shadow mask material plate 5 placed on the die 4 is clamped at its periphery by pressure applied by the descending blank holder 2.

Next, as shown in FIG. 4(a) to FIG. 4(C), the punch 1 is
descends and comes into contact with the shadow mask material plate 5 from the center, and the spherical surface begins to protrude.

Next, as shown in FIG. 5(a) to FIG. 5(C), the punch 1 further descends, the spherical surface protrudes, and the outer periphery 11 of the punch 1 becomes larger than the inner periphery 41 of the die 4. Figure 5 (a
In the X-axis cross-sectional view of ) and the Y-axis cross-sectional view of FIG. 5(b), it is located at the lower side, and in the diagonal-axis cross-sectional view of FIG. 5(C), it is located at the upper side.

Further, as shown in FIGS. 6(a) to 6(C), the punch 1 descends and comes into contact with the pad 3 at the outer circumferential portion of the spherical surface, thereby completing the spherical projecting process.

Below, a gap occurs between the die 4 and the blank holder 2,
The peripheral part of the shadow mask material plate 5 can be moved within the apparatus, and even after the die 4 reaches the lowest point, the punch 1 and the pad 3 descend to form the side wall part of the shadow mask (Fig. (not shown).

Considering the process of extending the spherical surface of the shadow mask using a model as shown in FIG. If the length of the material after being formed is Ll,
The strain ε generated at that time is expressed by the following formula.

Using a 20-inch CRT as a model, calculate the above formula.
R=800. Lx (Y axis) -400,L.

(Y axis)=300. L, (diagonal axis) = 480 m,
The strain in each axis is ε, (X-axis') −1,07(χ)
.

ε, (Y axis) = 0.60 (χ), εD (diagonal axis) −
1.56(χ), which results in a difference in the magnitude of strain in each axis.

In an actual press, the pad step H is provided, so the length after molding is L1+2H. FIG. 8 shows the calculated amount of distortion when changing the pad step L1 in this case.

If the pad height difference H is set to about 3 or 5 degrees as shown in FIG. 8, the amount of distortion between each axis will be approximated, and the difference in distortion will be reduced. However, in the case of the shadow mask material plate 5 having transmission holes, if a strain of 2% or more is applied, the transmission holes will be deformed or broken.Therefore, in practice, the band step difference that reduces the difference in strain on each axis will occur. It is impossible to get H.

However, by changing the band level difference H depending on each location as in the present invention, it is possible to provide equal or nearly equal distortion at all locations.

In the case of a 20 inch CRT, as shown in Figure 8,
In order to generate a strain of 1.8%, the pad height difference H on each axis must be 1.4 mm on the Y axis, 1.8 tm on the Y axis, and 0 on the diagonal axis.
．． It is better to take 6M.

However, in reality, when the mask material plate 5 is placed on the die 4,
As shown in FIG. 9, the pad is bent along the shape of the die 4 and is not a flat surface. Therefore, the pad step H needs to be determined in consideration of this bent state.

The pad height differences H other than those on each axis may be calculated one by one using the formula (1) above, but the pad height differences H calculated on each axis may be connected using any formula. In the case of CRT, trigonometric functions were used.

In the above example, the shadow mask is of a round hole type, so there is no need to consider anisotropy regarding the material strength. Since the strength of the materials differs greatly, it is necessary to change the processing degree. However, by using the shadow mask molding device of this invention, the processing degree can be set arbitrarily, so that the required amount of processing can be applied to the necessary parts. I was able to do that.

Actually, the pad level difference H on the X axis, and the buffed level difference H on the Y axis.
1. Diagonal axis band step H, when closed, Hv > I
It is preferable to configure ll and HI so that the band step difference on the side parallel to the transverse direction of the slot becomes large.

(Effects of the Invention) As described above, according to the present invention, the shape of the outer periphery of the punch and the pad is different from the shape of the inner periphery of the blank holder and the die, and the step between the pad and the die is formed into a round transparent hole. When forming a shadow mask material plate with a slot-shaped transmission hole, the minimum value should be set at or near a corner, and when forming a shadow mask material plate with a slot-shaped transmission hole, the minimum value should be set parallel to the short direction of the slot. Since the maximum strength is achieved at or near the center of the side, the molded shadow mask does not cause deformation or breakage of the transparent holes, and a -like spherical state is ensured, resulting in high strength and easy processing. It also has the effect of suppressing the occurrence of trench fatigue due to shortage.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a pad and die portion in a shadow mask molding apparatus according to an embodiment of the present invention, and FIG.
[D (a) to 2(C) are cross-sectional views of the first pad and die along the X-axis, Y-axis, and Y-axis, respectively, and FIGS. 3(a) to 3(C) to 6 (a) to Figure 6 (C)
are cross-sectional views on the X, Y, and Z axes of FIG. 1 for explaining the shadow mask forming device of the present invention, and FIG. 7 is a diagram showing the amount of strain calculated in the overhang process in the shadow mask forming device of the present invention. FIG. 8 is an explanatory diagram showing the relationship between the pad level difference and distortion determined by the model, and FIG. 9 is a diagram showing the shadow mask material placed on the die to be molded by the shadow mask molding apparatus of the present invention. FIG. 10(a) is a perspective view showing the state of the plate, FIG. 10(a) is a plan view showing the shape of slot-shaped transparent holes drilled in the conventional shadow mask material plate, and FIG. 10(b) is the conventional shadow mask material plate. FIG. 11 is a sectional view showing a conventional shadow mask forming device, and FIGS. 12 to 15 are a partial view showing a forming procedure using a conventional shadow mask forming device. The cross-sectional view in Figure 16 is made using conventional shadow mask molding! FIG. 17(a) is a front view showing the outer shape of the shadow mask formed in the process, and FIG.
) is a plan view showing a shadow mask transmission hole that has been deformed due to excessive processing, Figure 18 is a diagram showing an 8M hole formed using a shadow mask with a broken or deformed transmission hole, and Figure 19 is a plan view of a spherical hole. FIG. 3 is a cross-sectional view of a shadow mask showing a state in which a part of the shadow mask is elastically deformed and its tension is deteriorated. DESCRIPTION OF SYMBOLS 1... Punch, 2... Blank holder, 3... Pad, 4... Die, 5... Shadow mask material strip, 31... Pad outer periphery, 41... Die inner periphery . Note that the same reference numerals in the figures indicate the same or equivalent parts. Agent Masuo Oiwa Figure 1 Figure 2 (0) (b) (c)) 4:I('
'do j2 difference Figure 3 (σ) (bl
(c) Figure 7 Figure 8 Pad r Saraiwa 艷 (H) (fnl'rQ Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 15 Figure 16

Claims (1)

[Claims] A blank holder that presses the peripheral part of the shadow mask material plate, a die that is provided opposite to this blank holder and holds the shadow mask material plate by the blank holder, and a die that slides inside the blank holder and the die and A punch for forming a predetermined spherical surface portion and a skirt portion in the shadow mask material, and a pad that holds the shadow mask material plate with part or all of the surface facing the punch and slides within the die. In the shadow mask forming apparatus, the outer circumferential edge of the pad is located at least equal to or lower than the inner circumferential edge of the die, and the distance in the height direction between the inner circumferential edge of the die and the outer circumferential edge of the pad is H. When molding a shadow mask material plate with round-shaped transmission holes, the value of H becomes minimum at or near the corner, and when molding a shadow mask material plate with slot-shaped transmission holes, The shadow mask forming apparatus is characterized in that the value of H is maximum at or near the center of a side facing in the same direction as the lateral direction of the slot.