JPH0261029A - Inner shield material for TV cathode ray tube and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic shielding material for a color TV cathode ray tube (picture tube) (consisting of a mask frame, a shadow mask inner shield, an outer shield, etc.). The present invention relates to an inner shield material disposed so as to cover it from the side in the direction of electron beam passage, and a method for manufacturing the same.

[Prior Art] The basic structure of a color TV cathode ray tube consists of an electron gun and a fluorescent surface that turns the electron beam into an image, and the inside is covered with a magnetic shielding material that prevents the electron beam from being deflected by the earth's magnetism. .

The characteristics required for magnetic shielding materials are the geomagnetic field (approximately 0.3
It has a high magnetic permeability in a magnetic field of Oe (minimal magnetic field). Furthermore, in order to improve the demagnetizing characteristics, that is, to reduce the number of turns of the demagnetizing coil and the current, it is also required that the coercive force He be small.

In particular, the inner shield material placed inside the cathode ray tube so as to cover it from the side in the direction of passage of the electron beam,
It is important as a magnetic shielding material.

The thickness of the inner shield material is usually 0.10 to 0.25
This material (coil) is made of ultra-thin steel plate with a diameter of M11, and after being press-formed by an electrical manufacturer, it is subjected to a pre-blackening treatment at a temperature of around 600 degrees Celsius, and is often incorporated inside a cathode ray tube.

An examination of the inner shield materials of color TVs currently on the market before blackening treatment shows that the DC magnetic field is 0.3 Oe (μ0.3
) is about 300 emu.

In addition, the DC coercive force He at the maximum magnetizing force LOOe is also 1.8
There is only about 0e. The crystal grain size is determined by the ferrite grain size number (J
15-GO552) and is approximately 7 to 9.

However, JP-A-62-280328 and JP-A-6
Japanese Patent No. 2-280329 proposes a method for producing an inner shield material for cathode ray tubes having excellent moldability and electromagnetic shielding properties. The content of this proposal is to control the manufacturing process by using aluminum killed steel instead of conventional rimmed steel, and the holding force He-L, 8 after temper rolling (0.5%) is shown in the example. has been done.

As is well known, in an inner shield material, coercive force is an important property along with other properties. First of all, when the orientation of the TV is changed, it is necessary to demagnetize the magnetization (including vectors) of the shield material.

For this reason, a degaussing coil is generally provided, but from an economic standpoint it is required to reduce the number of turns and current of this coil. Therefore, the inner shield material must be as soft as possible, that is, the He content must be small.

Second, He has a strong correlation with μ0.3, and when He is small, μ shows a large value. In other words, a good μ0.30.3 (a characteristic that directly affects shielding properties) means that He
This is equivalent to a good He value, which is easily measured by electrical manufacturers. , 3 are often represented.

According to the investigation by the present inventors, as long as temper rolling is performed, He
It is difficult to reduce the value to 1.8 or less.

On the other hand, omitting skin pass rolling causes problems such as insufficient hardness and poor shape of the steel plate, resulting in poor handling properties at the customer's site.

[Problems to be Solved by the Invention] In view of the above points, the present invention provides μ. , 3 and a small He value, which has excellent magnetism, and at the same time provides an inner shield material with good shape and handleability.

[Means for Solving the Problems] The present invention provides C≦0.005%, Si≦0.3%, P:0.
1 ~ 0.4%, Mn 20, 1 ~
1.0%, S 60.01%.

AΩ: 0.01%, N≦0.01%, balance contains unavoidable components and iron, plate thickness 0.10-0.25mm, crystal grains are coarse grains with ferrite grain size number 7 or less, and hardness. A steel plate having an Hv (500 g) of 90 or more, a magnetic permeability of 750 efflu or more in a DC magnetic field of 0.3 Oe, and a coercive force of 1.20 c (maximum magnetizing force 1 one) or less for TV cathode ray tubes. It is an inner shield material, and furthermore, C≦0.05%, si≦OJ 96.
P: 0.1-0.4%, Mn: 0.1-1.
0%, S≦0.01%.

A hot-rolled steel plate is manufactured from a slab containing AΩ≦0.01%, N≦0.01%, and the remainder contains unavoidable components and iron, and is cold rolled to achieve a resistance of 0.01%. After making the plate thickness IO ~ 0.25 mm,
C≦0.00 by performing continuous annealing at a temperature of 750°C or higher
5%, and without temper rolling, the crystal grains are coarse grains with a ferrite grain size number of 7 or less, and have a hardness of Hv (500
g) is 90 or more, and the magnetic permeability in a DC magnetic field of 0.30 e is 7.
This is a method for producing an inner shield material for a TV cathode ray tube, characterized by obtaining a steel plate having a coercive force of 50 emu or more and a coercive force of 1.2 Oe (maximum magnetizing force 100 e) or less.

Hereinafter, the content of the present invention will be explained in detail.

The present inventors found that μ0.3≧750. We have developed an inner shield material that has excellent magnetism (He≦1.2) and is easy to handle.

The first point is to make the grain size≧ferrite grain size number 7, and the second is not to perform the final rolling, that is, not to apply strain to the steel sheet material.

Furthermore, the third point is that the basic composition of the steel sheet of the present invention is a soft steel, and as mentioned above, it is not subjected to temper rolling, so in order to compensate for the drawbacks, the hardness of the steel sheet is increased to Hv by solid solution strengthening. (500g) is 90 or more, which eliminates troubles such as squeezing, roll flaws, and breakage on the exit side of the continuous annealing line during the production of steel sheets according to the present invention, and at the same time improves the shape of the product material and furthermore improves the quality of the product at the customer's site. This improves handling properties during press working and blackening treatment.

First, we examined the component system of the material. Bozorth (Ferromanet 1st
n-D, Van No5trand Co., Pr.
1nccton, N, J,, P, 870°Tab
According to LE 2.1951), there are pure iron, electrical steel sheets, permalloy, etc. Therefore, it can be seen that in order to improve magnetic permeability, it is necessary to control the components or texture and select a special (expensive) material.

However, the present inventors have discovered that the magnetic permeability in the presence of a minute magnetic field on the order of geomagnetic field is determined only by the size of the crystal grain size and the amount of residual strain of the material rather than the component composition.

That is, steel containing the components shown in Table 1 is hot rolled, then cold rolled to a thickness of 15 mm and annealed at 700 to 1000°C.
When measuring the characteristics of a steel plate soaked with X3m1n, as shown in Figure 1, the influence of Si, Ajll, C, etc.
It was found that there was almost no effect within the range.

Rather, it depends only on the crystal grain size, which is changed depending on the heat treatment conditions, and the logarithm of magnetic permeability has a near relationship with the reciprocal of the crystal grain size.

Moreover, if a few percent of strain is applied to this steel plate, the magnetic permeability will deteriorate. This tendency was also true for coercive force. Therefore, the target μ0.3≧750. He≦1
．． In order to obtain 2, it is important to first make the crystal grain size of the inner shield material coarse grains of 7 or less, and then not to apply strain (rolling).

Table 1 (vt%) In addition, the steel plate softened by high temperature annealing to obtain coarse grains is
Because the handling properties are very poor, the hardness was reduced to 90 (yield point: approximately 17 kg/ml1) by solid solution strengthening (precipitation hardening elements are not preferred as they strongly suppress grain growth).
) or more.

The component system includes oxide inclusions (A) that suppress grain growth.
N203. MnO, Si02, etc.), precipitates (Mn
S, ANN, etc.) should be smaller.

In other words, 0. S, N, etc. should be reduced.

In addition, for the purpose of improving threadability, appropriate amounts of Mn, P, etc. are added to provide strength or rigidity as a steel sheet.

Hereinafter, the components will be explained first.

The C content of the product material must be 0.005% or less in terms of magnetic aging. C of this product material is subjected to decarburization annealing (for example, wet H2 + N2
(in an atmosphere), the C content after casting is within a range that does not impose a large load on the decarburization, that is, 0.05%.
It is allowed up to

Since Sl deteriorates the adhesion of the blackening film, it is set to 0.3% or less.

When Mn is 0.1% or less, fine precipitation of MnS occurs, which impairs crystal grain growth. Therefore, 0.1% or more is necessary, but if it increases too much, there will be a cost problem, so the upper limit is set to 1%.
．． Set to 0%. Note that Mn also has the effect of increasing hardness, although this is not the same as P, which will be described later.

P is very effective in increasing the hardness of steel sheets, with a minimum content of 0.1%
is necessary, but if it exceeds 0.4%, fine grains will be generated due to segregation, which is a problem. The purpose of adding P in the present invention is to effectively prevent troubles in the inner shield mill production line, such as squeezing, wrinkles, and scratches caused by pinch rolls during winding on the exit side of the continuous annealing furnace. In addition to improving the shape of the product material, it also improves handling at the customer's site. Hardness of steel plate Hv (500g
) is 90 or more, this objective is achieved.

Al is 0. If the content exceeds the old percentage, precipitation of A and QN will increase, so the content is preferably 0.01% or less. In addition, Al is 0.2%
There are methods such as adding the above to coarsen AΩN and improving grain growth, and using B to make AΩN harmless, but both are disadvantageous in terms of cost.

Also, the smaller the amount of S and N, the better in terms of grain growth.
Each content is preferably 0.01% or less.

Next, although there are no particular limitations regarding hot rolling,
The heating temperature of the slab is preferably a low temperature in order to suppress solid solution of precipitates, but if S and N are present in trace amounts, the influence will be small. Further, the hot rolling finishing temperature is preferably just below the A3 transformation point (910° C. for pure iron), but there is no problem even if the hot rolling is finished at a high temperature side, that is, in the γ phase, as long as the final continuous annealing is carried out at a slightly higher temperature. The hot-rolling winding temperature is high (650 to 85
0°C) is preferred.

It is easier to obtain coarse grains in the final product if the next hot-rolled sheet annealing is carried out, but it can also be omitted. In cold rolling, the stronger the reduction, the smaller the grain size after the next recrystallization annealing.
The rolling reduction ratio is preferably low, and the plate thickness after hot rolling is advantageously 31 or less.

The final annealing temperature has a strong influence on grain growth, and coarse grains with a grain size number of 7 or less cannot be obtained unless the temperature is at least 750°C or higher. Further, after soaking to a temperature higher than the A3 transformation point, the steel is hardened by rapid cooling (300° C./to in or higher), which is advantageous in terms of the rigidity of the steel plate.

The annealing atmosphere is a decarburizing atmosphere such as a humid H2+N2 atmosphere, and the annealing atmosphere is decarburized to C≦0.005% from C≦0.0596. Further, the final annealing must be performed in a continuous furnace. This is because, in the case of a batch furnace, if the temperature is raised to a high temperature of 750° C. or higher, the product becomes defective in shape, and temper rolling is unavoidable to correct the shape, making it impossible to obtain the high-performance shielding material that is the object of the present invention.

Note that when P is not included, coarse particles with a particle size number of 7 or less can be obtained even if the temperature is lower by about 30°C, but it is not possible to ensure a hardness of 90 or more.

[Example] Example 1 A continuously cast slab whose components were variously changed (Table 2) at the steelmaking stage was heated at 1200°C, finishing temperature was 860°C, and coiling temperature was 70°C.
A hot-rolled sheet of 3.0 mm was produced at 0°C. Then 0.1
Cold rolled to 5mm and wet annealed at 760°C for 3 minutes.
The decarburization was carried out in a 2+N2 atmosphere to reduce the carbon content to 0.005% or less.

The properties of this material were evaluated and Table 3 was obtained.

In addition, the characteristics of sample (2) were evaluated after 1% temper rolling was performed on the final annealed plate of sample (2). M1 constant of magnetic permeability was performed using an Epstein sample (JIS C2550).

弗2 table (νt%) Note) - is outside the scope of the present invention.

Materials with good magnetic permeability have large crystal grains. However, simply having large crystal grains will cause problems in continuous furnaces and special press forming operations (breakage, squeezing, stamping, etc.), so P should be set to 0.1.
It is necessary to add ~0.4%. Sample ■■ satisfying the range of the present invention had the target magnetic permeability≧750eIIlu, coercive force≦1.20, and hardness≧90.

Example 2 C: 0.0032. Sl: 0.001, Mn
:0.28. P:0.20. S: 0.0
03, Al! : 0.001, N: 0.
A slab of 0.015% Fe with the remainder heated at 1200°C, finishing temperature 870°C, winding temperature 700°C, 2.0mm
A hot-rolled sheet was manufactured.

Then 0. After cold rolling to 15 mm and annealing at various temperatures for 30 seconds in nitrogen gas, the properties were evaluated.

The results are shown in Table 4.

At an annealing temperature of 750° C. or higher, magnetic permeability ≧750 emu and coercive force ≦1.20 were obtained.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a high-performance inner shield material for a TV cathode ray tube.

[Brief explanation of the drawing]

FIG. 1 is a chart showing the influence of grain size on magnetic permeability of cold rolling. Agent: Patent attorney Tatsuo Chanoki, ? rl] 1 to 1 (spontaneous) January, 1986

Claims (1)

[Claims] 1. C≦0.005% Si≦0.3% P: 0.1 to 0.4% Mn: 0.1 to 1.0% S≦0.01% Al ≦0.01% N≦0.01% The balance contains unavoidable components and iron, the plate thickness is 0.10 to 0.25 mm, the crystal grains are coarse grains with a ferrite grain size number of 7 or less, and the hardness is Hv (500 g ) is 9
An inner shield material for a TV cathode ray tube, characterized in that it is a steel plate of 0 or more, has a magnetic permeability of 750 emu or more in a DC magnetic field of 0.3 Oe, and has a coercive force of 1.2 Oe or less (maximum magnetizing force of 10 Oe). 2. C≦0.05% Si≦0.3% P: 0.1-0.4% Mn: 0.1-1.0% S≦0.01% Al≦0.01% N ≦0.01% A hot-rolled steel plate is manufactured from a slab containing iron and the remainder is an unavoidable component, and cold rolled to a thickness of 0.10 to 0.25 mm.
After achieving a plate thickness of Moreover, the hardness Hv (500g) is 90 or more, and the DC magnetic field is 0.3O.
The magnetic permeability at e is 750 emu or more, and the coercive force is 1.
A method for producing an inner shield material for a TV cathode ray tube, characterized by obtaining a steel plate with a magnetization force of 2 Oe or less (maximum magnetizing force of 10 Oe).