JPH062905B2 - Method for manufacturing inner shield material for cathode ray tube having excellent moldability and electromagnetic wave shield characteristics - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method of manufacturing an inner shield material for a cathode ray tube.

[Conventional technology and its problems]

An inner shield material with a thickness of about 150 μm is attached to the inner wall of the cathode ray tube incorporated in the television receiver or the CPT device of various computers to shield the influence of the external electromagnetic field on the electron beam emitted from the electron gun. . Recently, in particular, a cathode ray tube having a higher definition has been required, and excellent characteristics are also required for this type of material. However, the inner shield material for cathode ray tubes not only has good electromagnetic wave shielding properties, but also needs to have a thin plate thickness for weight reduction. However, if the plate thickness is made thin, it is disadvantageous with respect to the shield property as shown in the following formula (1), and in order to compensate for this, it is necessary to enhance the soft magnetic property of the material, particularly the magnetic permeability μ.

However, f: frequency G: specific conductivity K _I : constant t: plate thickness μ: magnetic permeability In order to increase the magnetic permeability μ, it is effective to purify the steel components, secure the ferrite grain size, and perform strain relief annealing. Therefore, for this reason, conventionally, a large ferrite grain size is secured by annealing.

However, although high temperature annealing is effective for increasing the grain size, there is a risk of seizure when the shield material is subjected to such high temperature annealing. Therefore, rimmed steel with good grain growth can be obtained even at low temperature annealing. There is no choice but to use it, and there is a big problem that improvement of magnetic characteristics cannot be expected.

In addition, rimmed steel has the disadvantage that it is inferior in formability to killed steel, and because it does not have large magnetic properties and the magnetic properties of the shield material deteriorate due to processing, assembly by assembling or relatively light processing. Inevitably, it will become a shield material that requires, and the number of steps in assembly work will increase.

The present invention has been made in view of such conventional problems,
An object of the present invention is to provide a method capable of producing an inner shield material for a cathode ray tube which is excellent in electromagnetic wave shielding properties and is also excellent in moldability.

Therefore, in the present invention, C: 0.0030 wt% or less, Al: 0.005
~ 0.06wt%, N: 0.0030wt% or less containing slab,
Soaking temperature Ts and winding temperature Tc, which is a soaking temperature of 1000 ° C or more and satisfies Ts ≤ 1.65Tc + 121.25, 720 to 870 ° C
At the finishing temperature of up to 2.0 mm and hot rolled, then cold rolled to 650
Its basic feature is to carry out batch annealing or continuous annealing at a temperature of ℃ or higher.

The details of the present invention will be described below together with the reasons for the limitation.

In the present invention, Al killed steel is used in place of the conventionally used rimmed steel, and the manufacturing conditions are specified in order to improve the electromagnetic wave shielding characteristics of this Al killed steel. That is, as described above, in order to improve the electromagnetic wave shielding characteristics, purification of steel components, securing of grain size and strain relief annealing are effective. From such a viewpoint, the components and manufacturing conditions of the Al-killed steel are as follows. As prescribed.

In the present invention, the steel composition is C: 0.0030 wt% or less, Al: 0.005
-0.06wt%, N: 0.0030wt% or less.

When Al-killed steel is annealed after cold rolling, AlN precipitates and suppresses grain growth of ferrite. Therefore, when the annealing temperature is not sufficiently high, the grain structure becomes finer than that of rimmed steel. Therefore, in the present invention, N is 0.0030 wt% in order to suppress the precipitation amount of AlN as much as possible.
% Or less.

Further, Al has a lower limit of 0.005 wt% for the purpose of completely fixing N as AlN in order to prevent deterioration of the shield characteristics due to magnetic aging of N which is an interstitial element. However, if Al is added excessively, the economical efficiency is impaired and the shield characteristics are deteriorated, so 0.06 wt% is the upper limit.

The smaller the amount of C, the higher the magnetic permeability .mu., And as shown in FIG. Therefore, in the present invention, the C content in steel is set to 0.0030 wt% or less in the steelmaking degassing process. Table 5 shows some production examples and magnetic properties of each material obtained in the test in which the results of FIG. 2 were obtained. The test material N shown in Table 1
The slabs of O.3 to NO.5 and NO.9 were hot-rolled to a plate thickness of 1.2 mm under the conditions shown in Table 5, then cold-rolled to a plate thickness of 0.15 mm, and then batch-annealed. , Temper rolling rate 0.5%
Was subjected to temper rolling, and the magnetic properties of each of the obtained test materials were investigated.

In the present invention, the slab having the above composition is soaked at a temperature of 1000 ° C. or higher and Ts ≦ 1.65Tc + 121.25, where Ts: soaking temperature Tc: winding temperature and soaking temperature Ts Taking temperature Tc, 720-870 ℃
At the finishing temperature of 2.0 mm or less.

Although the present invention suppresses the amount of N as much as possible as described above, precipitation of N as AlN before cold rolling is an effective means for grain growth property for N existing in a small amount. The melting of AlN in the slab was suppressed as much as possible by the low temperature heating at the stage, and the AlN was precipitated as much as possible by the high temperature winding. The present inventors have found that by setting AlN to have a grain size of 700 Å or more, a sufficient grain size can be obtained without suppressing ferrite grain growth by AlN,
Therefore, the hot rolling temperature conditions were examined. That is, the slab of sample material No. 2 in Table 1 was hot-rolled to a plate thickness of 1.8 mm at a finishing temperature of 850 ° C while changing the soaking temperature Ts and the winding temperature Tc. The relationship between Tc and the AlN particle diameter after the winding treatment was investigated. FIG. 1 shows the results. By performing hot rolling so that the soaking temperature Ts and the winding temperature Tc satisfy Ts ≦ 1.65Tc + 121.25, A
It was found that the particle size of 1N could be 700 Å or more.

Further, in the present invention, the lower limit of the soaking temperature Ts of the slab is 1000 ° C.
And This is because hot rolling becomes difficult if the soaking temperature Ts is less than 1000 ° C.

In addition to the above conditions, a soaking temperature Ts of 1150 ° C. and a winding temperature of 650 ° C. are preferable in order to make the grain growth property more reliable.

In order to improve the soft magnetic properties, <100> in the plate surface direction.
It is desirable to increase the degree of integration of oriented crystals. However, as a result of investigations by the present inventors, in the inner shield material of Al-killed steel, when a sufficient ferrite grain size and component purification were achieved, no special component design and manufacturing process for texture control were performed. In addition, it was found that sufficient magnetic permeability can be obtained as the shield material, and further, that the inner shield material has little deterioration in soft magnetic characteristics due to processing, and that homogenization of the structure is an important factor in construction.

In the present invention, since C in steel that lowers the magnetic permeability is 0.0030 wt% or less in the steelmaking degassing step, the Ar ₃ point is close to 900 ° C., and it is necessary to secure the finishing temperature at the Ar ₃ point or more in the entire coil length. There are difficulties. Therefore, the present invention aims to make the structure uniform on the premise of finishing in the ferrite single phase region. Especially in the case of finishing in the ferrite region, in an ultra-low carbon steel targeted by the present invention, the magnetization direction is parallel to the plate surface after cold pressing / annealing {11
It was also clarified that the degree of integration of 0} <100> or {100} <001> could be easily increased. Therefore, in the present invention, the upper limit of the finishing temperature is set to 870 ° C., and the lower limit is set in consideration of the lower limit value of the winding temperature and the cooling on the runout table.
It was set to 720 ° C.

Further, in the present invention, hot rolling is performed to a plate thickness of 2.0 mm or less.
This is because when rolling with a large reduction rate in the cold rolling stage, the grain size becomes finer, so a large reduction rate is taken in the hot rolling stage to reduce the plate thickness and a reduction rate in the cold rolling is reduced. I tried to suppress it.

After hot rolling as described above, cold rolling is performed, and then 65
Batch or continuous annealing is performed at 0 ° C or higher.

The higher the annealing temperature, the better the grain growth property, which contributes to the improvement of the magnetic permeability μ. FIG. 3 shows the relationship between the annealing temperature and the grain growth properties and magnetic permeability. At the annealing temperature of 650 ° C. or higher, good grain growth properties and magnetic permeability improvement effects are obtained. Table 6 shows some production examples and the magnetic properties of each material obtained in the test in which the results of FIG. 3 were obtained. The slab of the test material No. 8 shown in Table 1 is shown in Table 1. Under the conditions shown in Table 6, hot rolling to a plate thickness of 1.2 mm, cold rolling to a plate thickness of 0.15 mm, batch annealing, and temper rolling with a temper rolling ratio of 0.5% were performed. The particle size and magnetic properties of each of the test materials thus obtained were examined.

However, in the case of batch annealing, if it is annealed in a too high temperature range, there is a risk of seizure of the steel strip, and the upper limit temperature is inevitably regulated. Therefore, in the method of the present invention, it is preferable to perform annealing in a gas floating type continuous heat treatment facility.

The shield material of the present invention manufactured as described above has a N content higher than that of the shield material manufactured by the conventional rimmed steel.
Since it is completely fixed as AlN and C in the steel is lowered to an extremely low level, magnetic aging has almost no problem and the shield characteristics are not deteriorated.

Further, the shield material manufactured by the method of the present invention has excellent formability as compared with the conventional rimmed steel. Although the molding causes deterioration of the soft magnetic properties, the material of the present invention has excellent initial shielding properties, and thus can maintain sufficient shielding properties even when subjected to a certain amount of molding processing.

FIG. 4 shows the relationship between the deformation amount ε and the initial magnetic permeability μ _{0 of} the shield material obtained according to the present invention in comparison with the conventional shield material made of rimmed steel. In comparison, since the initial magnetic permeability until annealing is high, even if the magnetic permeability decreases due to deformation, relatively high characteristics are obtained. As shown in the figure, when the deformation amount is up to 5.0%, the value exceeds the initial magnetic permeability of the conventional material when not processed. Therefore, in the material of the present invention, not only the surface property of the steel strip can be smoothed by pressure regulation, but also the shield material which is required to have a complicated shape can be easily applied. Table 7 shows some production examples in the test in which the results of FIG. 4 were obtained and the magnetic properties of the obtained materials. The test materials NO. 9 and NO. 1
The slab of No. 4 was hot-rolled to a plate thickness of 1.2 mm under the conditions shown in Table 7, then cold-rolled to a plate thickness of 0.15 mm, and then batch-annealed. The relationship with the characteristics was investigated.

〔Example〕

Example (I) Slabs having the components shown in Table 1 (test materials NO. 1, NO. 2 and NO.
Nos. 8 to 15) were hot-rolled to a sheet thickness of 1.2 mm under the conditions shown in Table 3, then cold-rolled to a sheet thickness of 0.15 mm, then batch-annealed, and the test material No. 1 About No. 13, temper rolling was performed at a temper rolling ratio of 0.5%. The magnetic properties of each of the obtained test materials were measured, and the mechanical properties of some of the test materials were also measured.

Table 2 shows the test materials NO. 1, NO. 11 and N in Table 3.
The mechanical properties of O.13 to NO.14 are shown, and it can be seen that the material of the present invention has higher elongation, higher value and n value than the comparative material, and has excellent formability.

In addition, Table 3 shows the DC magnetic characteristics of each test material, and in terms of the magnetic characteristics, the material of the present invention has good magnetic permeability,
Has a coercive force. In particular, the material of the present invention exhibits excellent electromagnetic wave shielding properties even when compared with the uncompressed comparative material (conventional material), even though the material of the present invention is regulated at 0.5%.

Example (II) The slab of sample material No. 1 shown in Table 1 was changed to 1.2
The sample was hot-rolled to a thickness of 0.1 mm, then cold-rolled to a thickness of 0.15 mm, continuously annealed at 700 ° C., and temper-rolled at 0.5% to examine the DC magnetic properties of each test material. The results are shown in Table 4 together with the hot rolling conditions.

[Effects of the Invention] According to the present invention described above, it is possible to efficiently manufacture an inner shield material for a cathode ray tube having excellent electromagnetic wave shielding properties and excellent moldability.

[Brief description of drawings]

FIG. 1 shows the relationship between the AlN grain size in steel and the heating temperature and coiling temperature in hot rolling. FIG. 2 shows the relationship between the C content in steel and the initial magnetic permeability. FIG. 3 shows the relationship between the annealing temperature, the grain size in steel and the initial magnetic permeability. FIG. 4 shows the relationship between the amount of deformation of the shield material and the initial magnetic permeability for the material of the present invention and the conventional material.

Claims (1)

[Claims] 1. C: 0.0030 wt% or less, Al: 0.005-0.06w
A slab containing t% and N: 0.0030 wt% or less at 1000 ° C
The soaking temperature Ts and the winding temperature Tc which satisfy the above-mentioned soaking temperature and Ts ≦ 1.65Tc + 121.25, 720 to 870 ° C.
At the finishing temperature of up to 2.0 mm and hot rolled, then cold rolled to 650
A method for producing an inner shield material for a cathode ray tube, which is excellent in formability and electromagnetic wave shielding characteristics, characterized by performing batch annealing or continuous annealing at a temperature of ℃ or higher.