JPH0534081B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a shadow mask which is intended to prevent adhesion seizure during annealing of a perforated flat mask.

[Conventional technology]

Conventionally, a shadow mask for a color television cathode ray tube is manufactured through various steps as shown in FIG. 1, for example. FIG. 1 shows a manufacturing method based on a post-annealing process that includes an annealing process after photoetching, and the process up to final cold rolling is the material manufacturing process at the material manufacturer. The thickness of this material is 0.3mm
The following steel strips are used, and the finishing cold rolling is done at a reduction rate of 40
% or more is normal. This material is usually dulled by direct dull rolling with dull processing rolls or by temper dull rolling. At this time, the round edges of the roll are created by subjecting the roll surface to grit blasting, liquid honing, electrical discharge machining, or the like. The shadow mask material produced in this manner is usually shipped in the form of a coil to an etching perforation manufacturer.

The etching perforation manufacturer uses a photo-etching process to make predetermined holes and then cuts them into flat masks. This flat mask is then normally shipped to a cathode ray tube manufacturer.

CRT manufacturers stack dozens to hundreds of flat masks as shown in Figure 2.
Annealing is performed at a high temperature of 650-800°C to improve press formability. The occurrence of stretcher strain after annealing is usually prevented by applying a roller leveler. Next, it is press-molded into the shape of a cathode ray tube, and finally subjected to a blackening treatment.

[Problem that the invention seeks to solve]

According to a method of manufacturing a shadow mask (post-annealing method) which includes a step of annealing the flat mask after the photo-etching perforation process (usually carried out by a cathode ray tube manufacturer), a problem of adhesion seizure occurs during the annealing. In other words, as described above, stack dozens to hundreds of flat masks.
When annealing is performed at a high temperature of 650 to 800℃, the flat masks may adhere to each other and become difficult to separate, which may adversely affect the shape of the precision-drilled hole.
Sometimes it can become a crease. This annealing process is a process that handles a flat mask that has been precisely photoetched and perforated, and is an established process in the post-annealing process, so the occurrence of defective products and decreased workability in this process have a large impact on manufacturability. This has a great influence on the quality and yield of the product shadow mask.

The present invention aims to provide a material for a shadow mask that can solve this problem.

[Means to solve problems]

According to the present invention, cold rolling or temper rolling is performed in the final process to produce a raw steel plate for a shadow mask, and this raw steel plate is used to perform photoetching and perforation treatment to produce a flat mask, and a large number of flat masks are produced. In the method for manufacturing shadow masks in which sheets are stacked and annealed, during the final cold rolling or temper rolling when manufacturing the materials for shadow masks, rolling is performed using rolls that have been dulled and then polished. A surface condition in which the roughness (Ra) is in the range of 0.2 to 2.0 μm and the skewness (Rsk), which is the deviation index in the height direction of the roughness curve defined below, is positive is imparted to the surface of the material for the shadow mask. A method for manufacturing a shadow mask is provided. Here, surface roughness (Ra) and skewness (Rsk) are defined as follows.

As shown in Figure 3, from the surface roughness curve (cross-sectional curve from which low-frequency components have been removed), a portion of length L is extracted in the direction of the center line, and the center line of this extracted portion is aligned with the When the roughness curve is expressed as y=y(x) with the direction as the Y axis, the following (1)
The value given by the formula expressed in μm is Ra
(center line average roughness).

Ra=1/L∫ ^L ₀ ｜y ² (x)｜dx……(1) Here, the center line of the roughness curve is the line between this straight line and the curve that is parallel to the average line of the roughness curve. An object whose enclosed area is equal on both sides.

On the other hand, as shown in Figure 4, skewness (Rsk) indicates the degree of deviation (skewness) in the height direction of the roughness curve, and is displayed by measuring the shape of the amplitude distribution curve. It is expressed by equation (2).

Rsk=1/Rq ³・N _N 〓 ⁱ (y _i −) ³ ...(2) However, Here, N: Number of ordinates on the curve y _i : Height of the ordinate: Average height Rq: Root mean square height According to this Rsk, the asymmetry of the shape is compared even on surfaces with the same values of Ra and Rq. If the profile has many peaks, the value of Rsk will be positive, and if the profile has many valleys, the value of Rsk will be positive.
The value of Rsk is negative.

If the material for a shadow mask has a surface with a surface roughness (Ra) of 0.2 to 2.0 μm and a positive skewness (Rsk), no adhesion will occur even when the flat masks are stacked and annealed, as will be described later. In order to manufacture a material for a shadow mask with such a surface, a roll that has been dulled and then polished is used as a roll in the final cold rolling (secondary cold rolling) or temper rolling after the second cold rolling. I found that it is better to use .

The surface of the material for shadow masks is usually dulled by secondary cold rolling or temper rolling after secondary cold rolling, but this is done by grit blasting, liquid honing or electrical discharge. This is done by using processed rolls. Since the cross-sectional profile of the surface of this dull rolling roll or dull temper rolling roll has a highly uneven shape, the cross-sectional profile transferred to the material side also has peaks and valleys of approximately 1:1. , or the profile tends to have many valleys. In the present invention, by polishing the surface of a roll for dull rolling or a roll for dull temper rolling, more specifically, by further polishing after grit blasting, liquid honing, or electric discharge machining. , the crests of the roll are shaved off to create a profile with many valleys. Then, using this roll, secondary cold rolling or skin pass rolling is performed after secondary cold rolling to form dull marks.
This results in surface roughness (Ra) on the material side surface.
The roughness profile can be made into a roughness profile with a positive skewness (Rsk) of 0.2 to 2.0 μm and many peaks. In addition, as an accompanying effect of polishing treatment,
Firstly, since the ridges on the roll side are reduced and smooth, there are fewer pinholes on the material side and the cross-sectional shape of the hole becomes better during the etching process.Secondly, the roll itself is rough. One of the advantages is that uniform products can be manufactured with less wear and tear and a long service life.

FIG. 5 shows the process of dull rolling in the final cold rolling in the shadow mask material process shown in FIG. 1.
This figure shows the surface roughness profile of a material product when the material for a shadow mask was manufactured using the same steel, manufacturing process, and conditions, except that the type of roll was changed.

Comparative Example (1) is an example in which a roll that has been dulled (without polishing treatment) is used, and this roll has a roughness profile with a long wavelength as shown in the figure. The material products obtained using this profile roll have a surface roughness (Ra) of 0.2~
Although it was in the range of 2.0 μm, the skewness (Rsk) was −0.3. When 50 of these flat masks were stacked and annealed at a temperature of 750°C for 10 minutes, they adhered to such an extent that they would not peel off unless they were subjected to considerable vibration.

Comparative example (2) used a roll that had been dulled (no polishing treatment) as in comparative example (1), but the dulling conditions were changed to create a roll with a precise roll roughness profile with a short wavelength. This is an example using . Material products using this roll have the same surface roughness (Ra) as Comparative Example (1), skewness (Rsk) of −0.1, and no adhesion when annealed under the same conditions as Comparative Example (1). occured. From this, it can be seen that the length of the wavelength in the roughness profile does not cause a large significant difference in contact baking.

Example (3) is an example in which a roll having a profile in which the peaks as shown in the figure are removed is used by performing the same dulling as in Comparative Example (2) and then polishing. The surface of the material product obtained using this polishing roll had a profile with many ridges as shown in the figure. In other words, the surface roughness is equivalent to comparative examples (1) and (2), but
Skewness (Rsk) was 0.2. In this case, no adhesion occurred during annealing under the same conditions as in the comparative example.

In this way, in order to prevent adhesion seizure during flat mask annealing, polishing is performed after dulling to create a dull mark with a roll with a roughness profile with many valleys, and if the Rsk of the product material is 0 or more. It has been found that it is important to have a positive value.

Regarding surface roughness (Ra), Ra is 0.2μ.
If it is less than m, the unevenness is small, so even if the cross-sectional shape of the roughness is improved, the contact area between the flat masks becomes large, and Rsk does not work effectively to prevent annealing adhesion. On the other hand, if Ra exceeds 2.0 .mu.m, the shape of the hole becomes poor during etching, so Ra needs to be in the range of 0.2 to 2.0 .mu.m.

[Brief explanation of drawings]

Fig. 1 is a process diagram to explain the normal manufacturing process of a shadow mask, Fig. 2 is a perspective view showing the stacked annealing state of flat masks, and Fig. 3 is a model profile diagram to explain the surface roughness (Ra). , FIG. 4 is a model profile diagram for explaining skewness (Rsk), and FIG. 5 is a diagram showing the relationship between the roll roughness profile and the raw product roughness profile, showing the results of an example of the present invention.

Claims (1)

[Claims] 1. In the final step, cold rolling or temper rolling is performed to produce a steel plate for a shadow mask, and this steel plate is photo-etched and perforated to produce a flat mask. Many of the obtained flat masks are stacked and annealed. In the method for producing a shadow mask to be processed, during the final cold rolling or temper rolling in the production of the material for the shadow mask, rolling is performed using rolls that have been dulled and then polished, thereby improving the surface roughness ( Ra) is 0.2
A shadow mask characterized in that the surface of the material for the shadow mask is given a surface condition in which the skewness (Rsk), which is the deviation index in the height direction of the roughness curve defined in the main text, is positive in the range of ~2.0 μm. Manufacturing method.