JPS62280328A - Manufacture of inner shielding material for cathode-ray tube excellent in formability and electromagnetic wave-shielding characteristic - Google Patents

Abstract

PURPOSE:To manufacture an inner shielding material for cathode-ray tube excellent in formability and electromagnetic wave-shielding characteristic, by subjecting a slab in which respective contents of C, Al, and N are limited to hot rolling to the full under specific conditions, to cold rolling, and then to annealing at high temp. CONSTITUTION:The slab containing, by weight, <=0.0030% C, 0.005-0.06% Al, and <=0.0030% N is hot-rolled to <=2.0mm under the conditions of soaking temp. Ts and winding temp. Tc satisfying Ts<=1.65Tc+121.25 and of a finishing temp. of 720-870 deg.C, so that AlN in the slab is inhibited from melting and precipitated as much as possible into a sufficient grain size and, simultaneously, draft in cold rolling is reduced so as to prevent grain refining. The resulting hot-rolled plate is cold-rolled and then is subjected to batch annealing or to continuous annealing at >=650 deg.C so as to accelerate grain growth. In this way, the inner shielding material for cathode-ray tube excellent in formability and electromagnetic wave-shielding characteristic can be efficiently obtained.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Industrial Application] 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 approximately 15,011 m thick is attached to the inner wall of a cathode ray tube built into a television receiver or a CPT device of various computers in order to shield the electron beam emitted from an electron gun from the influence of external electromagnetic fields. . Recently, in particular, there has been a demand for higher-definition cathode ray tubes, and this type of material is also required to have excellent properties. However, the inner shield material for cathode ray tubes not only has good electromagnetic shielding properties, but also has to be thin to reduce weight. However, reducing the plate thickness is disadvantageous in terms of shielding properties as shown in equation (1) below, and in order to compensate for this, it is necessary to increase the soft magnetic properties of the material, particularly the magnetic permeability μ.

Absorption loss A = +t Noah stone f ・1 song...Pa°°What 1)
However, f Double layer wave number G: Specific conductivity KI: Constant t: Plate thickness μ: Magnetic permeability In order to increase the magnetic permeability μ, it is effective to purify the steel components, ensure the ferrite grain size, perform stress relief annealing, etc. Therefore, conventionally, a large ferrite grain size is secured by annealing.

However, although high-temperature annealing is effective in increasing the grain size, there is a risk of seizure when subjecting shielding materials to such high-temperature annealing, so rimmed steel, which has good grain growth even when annealed at low temperatures, is Rimmed steel has the disadvantage of being inferior in formability compared to killed steel, and it is not possible to obtain large magnetic properties, and it is difficult to shield. Since the magnetic properties of the material deteriorate due to processing, the shielding material must be assembled by mating or processing at a relatively long distance, which increases the number of man-hours for assembly.

The present invention was made in view of such conventional problems,
``It is an object of the present invention to provide a method for producing an inner shield material for cathode ray tubes that has excellent WL magnetic wave shielding properties and excellent moldability.

Therefore, in the present invention, C: 0.0030 wt% or less, A
l: 0.005-0.06 wt%, N: 0.00
A slab containing 30 wt% or less is heated to a soaking temperature TS and a winding temperature [TC, which satisfies TS≦1.65 TC+ 121.25, at a finishing temperature of 720 to 870°C. Hot rolled to O1 or less, then cold rolled to 650
Its basic feature is batch annealing or continuous annealing at temperatures above ℃.

The details of the present invention will be explained below along with its limitations.

The present invention uses Al-killed steel instead of the conventionally used rimmed steel, and defines manufacturing conditions in order to improve the electromagnetic shielding characteristics of this Al-killed steel. In other words, as mentioned above, in order to improve the electromagnetic shielding properties, it is effective to purify the steel components, secure the grain size, and annealing to remove strain. From these points of view, the composition and manufacturing conditions of Al-killed steel are determined as follows. It was stipulated as follows.

In the present invention, the steel composition is C: 0.0030wt% or less1
, ht: Q, 005-0.06 wt%, N:
It is regulated to 0.0030wt% or less.

When Al-killed steel is annealed after cold rolling, AIN precipitates 1 and suppresses ferrite grain growth.

Therefore, if the annealing temperature is not high enough, it will have a finer grain structure compared to rimmed steel. Therefore, in the present invention, N is set to 0.0030 wt% or less in order to suppress the amount of AlN precipitation as much as possible.

Furthermore, in order to prevent deterioration of shielding properties due to magnetic aging of N, which is an interstitial element, the lower limit of Al was set at 0.005 wi% in order to completely fix N as AIN. However, adding too much Al impairs economic efficiency.
Also, since the shielding characteristics deteriorate, 0.06 wt
The upper limit is %.

The magnetic permeability μ improves as the amount of C decreases, and as shown in FIG. 2, the magnetic permeability significantly improves particularly at 0.0030 wt % and below. Therefore, in the present invention, the amount of C in steel is set to 0.0030 wt% or less in the steelmaking degassing step.

In the present invention, a slab having a composition as shown above is prepared with TS≦1.
65 TC+ 121.25 However, TS: Soaking temperature TC: Soaking temperature TS and winding temperature TC that satisfy the winding temperature, 720 ~
Hot rolled to a thickness of 2.0 m or less at a finishing temperature of 870°C.

As described above, in the present invention, Ni- is suppressed as much as possible, but for the N that is present in a small amount, precipitating it as AlN before cold rolling is an effective means for improving grain growth.

In the hot rolling stage, melting of AlN in the slab is suppressed as much as possible by low temperature heating, and A1. An attempt was made to precipitate as much N as possible. The present inventors found that by setting AlN to a grain size of 7QOλ or more, a sufficient grain size could be obtained without suppressing ferrite grain growth by red N, and investigated the hot rolling temperature conditions for this purpose. As a result, A
It was found that the particle size of IN could be increased to 700A or more.

In addition, in order to ensure grain growth, in addition to the above conditions, soaking temperature TS≦1150°C and winding temperature≧6
The temperature is preferably 50°C.

In order to improve the soft magnetic properties, it is necessary to
>It is desirable to increase the concentration of oriented crystals. However, the inventors have investigated that if the inner shield material of M-killed steel has sufficient ferrite grain size and component purification, there is no need to go through special component design and manufacturing process aimed at texture control. Both materials have sufficient magnetic permeability as a shielding material, and the inner shielding material has little deterioration in soft magnetic properties due to processing.
It was also found that homogenization of the structure is an important factor in construction.

In the present invention, since C in the steel, which reduces magnetic permeability, is reduced to less than o, ooaowt% in the steelmaking degassing process, the Ar point is 9.
The temperature is close to 00°C, and it is difficult in the process to ensure a finishing temperature at three or more Ar points over the entire length of the coil. Therefore, the present invention aims to make the structure uniform on the premise of finishing in the ferrite single phase region.When finished in the 1% ferrite region, the ultra-low carbon steel targeted by the present invention has After cold pressing and annealing, the magnetization direction is parallel to the plate surface (1, 10) <100> or (too
It also became clear that the degree of integration of f<oot> was 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 to 720°C, taking into consideration the lower limit of the winding temperature and cooling on the runout table.

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

After hot rolling as described above, cold rolling is performed, and then 6
Batch or continuous annealing is performed at 50°C or higher.

The higher the temperature of the annealing source y, the better the grain growth, which contributes to improving the magnetic permeability μ. FIG. 3 shows the relationship between annealing temperature, grain growth, and magnetic permeability, and shows that good grain growth and magnetic permeability improvement effects are obtained at an annealing temperature of 650° C. or higher.

However, in the case of batch annealing, if annealing is performed in a too high temperature range, there is a risk of seizure in the W4 band, and the upper limit temperature will inevitably be regulated.

Therefore, in the method of the present invention, it is preferable to perform annealing in a gas floating type continuous heat treatment equipment.

The shielding material of the present invention manufactured as described above is different from the conventional shielding material manufactured using rimmed steel (compared to N
Since it is completely fixed as AIN and the C content in the steel is reduced to an extremely low level, it has extremely excellent properties such that magnetic aging is almost a problem and there is no deterioration in shielding properties.

Furthermore, the shielding material manufactured by the method of the present invention has superior formability compared to conventional rimmed steel. Molding also causes deterioration of soft magnetic properties, but the material of the present invention has excellent initial shielding properties, so it is possible to maintain a sufficient shielding percentage even after being subjected to a certain degree of molding.

Figure 4 shows the relationship between the deformation amount ε and the initial magnetic permeability μ0 of the shielding material obtained by the present invention in comparison with that of the shielding material made of conventional rimmed steel. Since the initial magnetic permeability as annealed is high, relatively high properties are obtained even if the magnetic permeability decreases due to deformation. As shown in the figure, if the amount of deformation is up to 5.0%, the initial magnetic permeability exceeds the unprocessed initial magnetic permeability of the slave material. Therefore, with the material of the present invention, not only can the surface quality of the steel strip be made smooth by pressure adjustment, but also it can be easily applied to shield materials that require a complicated shape.

〔Example〕

0 Example (1) A slab with the components shown in Table 1 was processed into a J! ! 1.2m
After hot rolling to a thickness of 0.15 m+, batch annealing at 700°C, and further test materials No. 1 to
As for 凰3, temper rolling was performed at a pressure adjustment rate of 0.5%, and the mechanical properties and magnetic properties of each of the obtained test materials were investigated.

Table 2 shows the mechanical properties of each sample material, and it can be seen that the material of the present invention has higher elongation, F value, and n value than the comparative material, and has excellent formability.

Further, Table 3 shows the DC magnetic properties, and in terms of these magnetic properties, the materials of the present invention have good magnetic permeability and coercive force. In particular, even though the material of the present invention is subjected to 0.5% pressure regulation, it exhibits superior electromagnetic shielding properties compared to the comparative material (conventional material) in which pressure is not regulated.

j□l+10 Example (11) A slab with the components shown in Table 1 was hot rolled to a thickness of 1.2 mm under different conditions, then cold rolled to a thickness of 0.15 mm, and then rolled at 700°C. After continuous annealing and further 0.5% temper rolling, the DC magnetic properties of each sample material were investigated. The results are shown in Table 4 along with the hot rolling conditions.

〔Effect of the invention〕

According to the present invention described above, it is possible to efficiently produce an inner shield material for cathode ray tubes that has excellent magnetic wave shielding properties and excellent moldability.

[Brief explanation of drawings]

FIG. 1 shows the relationship between the AlN grain size in steel and the heating temperature and rolling weight in hot rolling. Figure 2 shows Steel Medium C.
This shows the relationship between the amount and initial permeability. FIG. 3 shows the relationship between annealing temperature, grain size in steel, and initial magnetic permeability. FIG. 4 shows the relationship between the shielding material deformation amount and the initial magnetic permeability for the present invention material and the conventional material. Patent applicant: Nippon Kokan Co., Ltd. Inventor: Akira Nishimoto
Yoshi Hosoya Butsuma
Shun Akira Urabe a3 Diagram pure temperature (0C) 4th diagram fork shape lε ('110)

Claims (1)

[Claims] C: 0.0030wt% or less, Al: 0.005-0.
06wt%, N: 0.0030wt% or less, at a soaking temperature T_S and a coiling temperature T_C that satisfy T_S≦1.65T_C+121.25, 72
An inner shield for cathode ray tubes with excellent formability and electromagnetic shielding properties, characterized by hot rolling to a thickness of 2.0 mm or less at a finishing temperature of 0 to 870°C, and batch or continuous annealing at 650°C or higher after cold rolling. Method of manufacturing wood.