WO2000073526A1

WO2000073526A1 - Steel sheet for heat shrink band with slight color misregistering

Info

Publication number: WO2000073526A1
Application number: PCT/JP1999/002856
Authority: WO
Inventors: Nobuo Yamagami; Kunikazu Tomita; Yasuyuki Takada; Yoshihiko Oda; Chohachi Sato; Teruo Takeuchi; Ichiro Saito; Hiroaki Kato
Original assignee: Nkk Corporation; Sony Corporation
Priority date: 1998-01-26
Filing date: 1999-05-28
Publication date: 2000-12-07
Also published as: EP1114880A1; KR20010106417A; EP1114880A4

Abstract

A steel sheet for a heat shrink band with a slight misregistering which has a yield stress of 24kg/mm2 or higher and a product of a magnetic permeability ν and a sheet thickness of 400 or larger in a magnetic field of 0.30e.

Description

Description Steel plate for heat shrink band with less color shift [Technical field]

The present invention relates to a steel plate applied to a heat shrink band for tightening around a panel portion in a color cathode ray tube such as a television, and more particularly to a steel plate for a heat shrink band having a small color shift.

[Background technology]

Steel The color cathode ray tube, the tube body 1. Since a high vacuum of 0 X 1 0- ⁷ T orr, from the viewpoint such as preventing deformation and tube inner explosion prevention of the panel surface, which is formed into a band shape A heat-shrink band consisting of is provided around the panel section, which applies tension to correct the deformation of the panel surface.

Furthermore, such a heat shrink band also has a function of shielding the terrestrial magnetism as well as the internal magnetic shield. It has a function to prevent it.

Conventionally, mild steel plates have been used for this heat shrink band. However, in the case of mild steel sheets, geomagnetic drift is relatively large, the tolerance for preventing color shift is narrow, and there is a strong demand for a material that can effectively prevent color shift.

[Disclosure of the Invention] An object of the present invention is to provide a steel sheet for a heat shrink band which has a small geomagnetic drift and a small color shift while maintaining a tension equal to or higher than that of a conventional steel sheet.

According to one aspect of the present invention, a yield stress is 24 kg / mm ² or more, and a product of a magnetic permeability 〃 and a sheet thickness in a magnetic field of 0.3 Oe is 400 or more, Fewer heat shrink band steel sheets are provided.

According to another aspect of the invention, C: 0.005% or less, N: 0.005% or less, P: 0.1% or less, S: 0.02% or less, Si: 0% by weight. 2% or more, 3.0% or less, Mn: 1.0% or less, so 1. A1: 1.0% or less, yield stress of 24 kg / mm ² or more, and 0.3 Oe magnetic field The product of the heat shrink band with little color shift, characterized in that the product of the magnetic permeability 〃 and the sheet thickness in the sheet is 400 or more.

The present inventors have obtained the following findings as a result of repeated studies for achieving the above object.

(1) When the product // Xt of the magnetic permeability 〃 and the sheet thickness t at 0.30 e, which is the external magnetic field strength at the geomagnetic level of the band steel sheet material, is 400 or more, the color shift can be improved.

(2) In order to maintain the above magnetic permeability while maintaining the strength equal to or higher than that of conventional steel, it is necessary to add 3: 1 by 0.2% or more by weight%.

The present invention having the above configuration has been completed based on such findings.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the product of the magnetic permeability / z and the plate thickness in a magnetic field of 0.30 e and the geomagnetic drift property, Figure 2 shows the relationship between the Si content of the steel sheet and the magnetic permeability における at a magnetic field of 0.30 e.

Fig. 3 is a diagram showing the relationship between the Si content of the steel sheet and the geomagnetic drift property, and Fig. 4 is a diagram showing the relationship between the Si content of the steel plate and the yield stress (YS).

[Best Mode for Carrying Out the Invention]

Hereinafter, the present invention will be described in detail.

First, the circumstances that led to the present invention will be described.

1. Relationship between color shift and magnetic permeability

Figure 1 shows C: 0.003%, Si: 1.35%, Mn: 0.20%, P: 0.05%, S: 0.003%, A1: 0.20%, N : 0.002% steel having a composition of 2% is melted in a laboratory, then hot-rolled, then cold-rolled to 0.8-1.2mmt, 500 ° (: annealing at 90 ° C for up to 800 ° C for 90 seconds) After the application, the band was processed into a band of a predetermined shape, heated to 500 ° C, fitted to a 29-inch TV cathode ray tube panel, and evaluated for geomagnetic drift properties.

In addition, mild steel as conventional steel (C: 0.035%, Si: 0.02%, Mn: 0.20%, P: 0.03%, S: 0.01%, A1: 0. 02%, N: 0.0027%), cold-rolled to 1.2 mm t, annealed at 600 ° C, band-processed, and shrink-fitted under the same conditions to obtain geomagnetic drift properties. An evaluation was performed.

The horizontal axis in the figure is the permeability measured at 0.30 e, an external magnetic field equivalent to geomagnetism, measured after applying a heat treatment equivalent to shrink fitting to a ring specimen taken from the annealed plate before shrink fitting. The product of the thickness and the sheet thickness t // is the value of Xt.

Bh and Bv on the vertical axis indicate the drift amount of the landing point of the electron beam. Specifically, 0.350 e for CRT With the vertical magnetic field and the horizontal magnetic field of 0.30 e applied, the CRT was rotated 360 °, and the displacement (landing error) of the landing point of the electron beam with respect to the reference point was measured. The value of the beak was taken as the horizontal drift amount Bh. The horizontal magnetic field was set as OOe, and the landing error when the vertical magnetic field was changed from 0〇6 to 0.35〇e was measured as the vertical drift amount Bv. The drift amount of the landing error on the vertical axis is shown as a relative value when the above-mentioned mild steel value is set to 1.

As is evident from Fig. 1, Bh and Bv both tend to decrease as xt increases, and the color shift due to geomagnetism is improved by increasing 〃xt. 2. The relationship between the amount of Si and the amount and strength of geomagnetic drift

Figure 2 shows C: 0.002%, Mn: 0.24%, P: 0.02%, S: 0.003%, A1: 0.22%, N: 0.0028%, and S i Fig. 3 is a graph showing the value of the magnetic permeability at 0.3 Oe of the band material of 1.01111111: when the amount is changed, and Fig. 3 similarly shows the amount of geomagnetic drift when the Si is changed. FIG. Up to 2% Si, increasing Si increases the permeability of the material and consequently reduces the amount of geomagnetic drift. In particular, when the Si content is 0.2% or more, the geomagnetic drift amount is superior to conventional steel. If it exceeds 2%, the permeability will increase, but the effect of improving the amount of geomagnetic drift will be small. The reason for this is not clear, but it is considered that the high-temperature strength of the band steel increased with an increase in the Si content in the steel, and the adhesion between the band and the panel surface changed.

In other words, when the amount of Si in the steel increases, the high-temperature strength increases due to solid solution strengthening of the Si, and the band tension at high temperatures increases. During shrink fit cooling, when the band shrinks and the panel starts tightening, the processing accuracy will be high. The shape of the band deformed due to heat or uneven heating temperature is easily frozen, and the band does not adhere to the entire panel even when cooled to room temperature. As a result, sufficient magnetic shielding cannot be performed, and the amount of magnetic drift is not improved as much as the permeability increases.

Fig. 4 shows the relationship between the yield strength and the Si content of the above-mentioned steel. Yield strength increases with the amount of S i is increased, the 24 k gf / mm ² or more is the intensity of conventional steel by the addition of 2% or more 0.5.

The findings of (1) and (2) described above are based on the above results, and the present invention is based on these results.

The present invention, yield stress is 24 kg / mm ² or more, by the product of the contact Keru permeability // and the plate thickness on the magnetic field of 0. 3 Oe is defined as more than 400, maintaining the conventional equivalent strength While it effectively prevents color misregistration, the preferred composition range is% by weight, C: 0.005% or less, N: 0.005% or less, P: 0.1% or less, S: : 0.02% or less, S i: 0.2% or more and 3.0% or less, Mn: 1.0% or less, s 01. A1: 1.0% or less. Hereinafter, the reason why the preferable range of the component is defined as described above will be described.

S i: S i is the most important component in the present invention. By adding Si, it is possible to increase the magnetic permeability while increasing the strength by solid solution strengthening. Such strength / permeability balance is excellent when Si is contained at 0.2% or more, and the strength and permeability are higher than those of conventional steel. However, when Si exceeds 3%, workability is remarkably reduced, so that 3% or less is preferable. From the viewpoint of color misregistration, the Si amount at which the drift amount is significantly improved is more preferably 1% or more and 2% or less.

C: C is an element that contributes to the strengthening of the steel sheet. However, C is more unfavorable for the magnetic permeability. It is preferably 005% or less.

Mn: Mn is preferably added at 0.1% or more to improve hot ductility. However, if added in excess of 1.0%, the magnetic permeability will deteriorate, so it is preferably 1.0% or less.

P: P is an element that contributes to the strengthening of the steel sheet, and may be added as necessary. However, if the content exceeds 0.2%, the steel sheet becomes brittle and causes problems such as coil breakage during cold rolling. Therefore, the content is preferably 0.2% or less.

S: S is not preferable for both hot ductility and magnetic permeability, and is preferably 0.02% or less from the viewpoint of not adversely affecting these.

sol. Al: sol. A1 deteriorates workability. In order to prevent this effect, the content is preferably 1.0% or less.

N: Like C, N is an element that is not desirable for magnetic permeability more than contributing to the strengthening of the steel sheet. To prevent this adverse effect, its content is preferably set to 0.005% or less. .

In addition, the heat shrink band may be subjected to plating from the viewpoint of corrosion resistance. Even in this case, if the characteristics before plating satisfy the range of the present invention, the desired characteristics can be obtained. .

[Example]

After smelting the test steels in Table 1, they were reheated to 1200 ° C and hot rolled to a plate thickness of 3.2 mm at a finishing temperature of 820 ° C and a winding temperature of 680 ° C. The obtained hot rolled sheet was pickled, cold rolled to a sheet thickness of 0.8 to 1.2 mm, and then annealed at 700 ° C for 90 seconds. These steel sheets were further heated at 500 ° C for 5 seconds, equivalent to heat shrink, and air-cooled to room temperature, and then yield stress and DC magnetic properties (when excited to a magnetic permeability of 0.30 e and 0.5 T Coercivity Force) was measured. In addition, 700 ° C annealed material is processed into a band of a predetermined shape, and 500 for a 29-inch TV cathode ray tube panel. After heating into C, geomagnetic drift was evaluated. The results are shown in Table 2. In Table 2, Bh and Bv are horizontal drift amounts and Βν is a vertical drift amount, and are shown as relative values when the value of mild steel is 1 as described above.

Test steels ある to ある whose test steel components are within the above preferred ranges are steels of the present invention satisfying a yield stress of YS ≥24 kgf / mm \ / xt≥400, and have a geomagnetic drift lower than that of conventional mild steel sheets. It was confirmed that the value was low. On the other hand, the test steels F to H which are out of the preferable range are comparative steels in which either the yield stress or the magnetic permeability is out of the range of the present invention, and the test steels whose geomagnetic drift property is a conventional mild steel sheet. It was about the same as I, and it was confirmed that the characteristics were not sufficient as a heat shrink band for cathode ray tubes.

table 1

(wt%) Steel C Si Mn P S sol.Al T.N.

A 0.0030 1.41 0.2 0.05 0.003 0.25 0.0010 Invention

B 0.0025 1.86 0.22 0.04 0.03 0.30 0.0015

C 0.0025 2.75 0.24 0.08 0.003 0.31 0.0025

D 0.0033 1.08 0.2 0.04 0.004 0.25 0.0022

E 0.0021 0.25 0.55 0.08 0.003 0.45 0.0014

F 0.0019 0.12 0.15 0.05 0.002 0.22 0.0022 Comparative example

G 0.0065 1.27 0.37 0.03 0.004 0.35 0.0027

H 0.0033 1.33 0.31 0.09 0.004 0.55 0.0068

1 0.0350 0.02 0.2 0.03 0.01 0.02 0.0027 Conventional steel Table 2

Claims

The scope of the claims

1. A heat shrink band steel sheet with a small color shift, with a yield stress of 24 kg / mm ² or more and a product of the permeability // and the sheet thickness in a 0.3 Oe magnetic field of 400 or more.

2. By weight%, C: 0.005% or less, N: 0.005% or less,

P: 0.1% or less, S: 0.02% or less, Si: 0.2% or more and 3.0% or less, Mn: 1.0% or less, so 1. A1: 1.0% or less A heat-shrink band steel sheet with little color shift, with a yield stress of 24 kg / mm ² or more and a product of the permeability ^ and the sheet thickness in a magnetic field of 0.30 e of 400 or more.