Method of leveling strips and leveling equipment of strips

Details Method of leveling strips and leveling equipment of strips Method of leveling strips and leveling equipment of strips

2000-02-04

2001-06-05

Crane, Daniel C. (Department: 3725)

Metal deforming

By deflecting successively-presented portions of work during...

By use of deflected arranged to provide longitudinally...

C072S205000

Reexamination Certificate

active

06240762

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a method of leveling strips and a leveling equipment of strips.
Required of strips for the production of parts for electrical and electronic apparatus are a high degree of flatness and a characteristic that parts cut out from the strips by etching do no warp. The present invention relates to a technique for rectifying the shapes of strips so that the rectified strips meet the two requirements.
The following prior arts for rectifying the shapes of strips are available.
(1) Method of rectifying the shapes of strips with a tension leveler
By using this method, the flatness of the strip can be improved below 0.5% in terms of the ratio of the height of a circular arc to the length of its chord, but the residual stress in the strip is high, causing parts cut out from the strip by etching to warp to a significant degree.
(2) Method of rectifying the shapes of strips by low-temperature annealing
By using this method, the residual stress in the strip can be reduced below 50 N/mm
2
so that parts cut out from the strip develop no substantial warps, but the flatness of the strip is over 1.0% in terms of the ratio of the height of a circular arc to the length of its chord.
In accordance with the above, the object of the present invention is to provide a leveling method and a leveling technique which secure a high degree of flatness of strips and give strips a characteristic that parts cut out from them by etching do not warp.
SUMMARY OF THE INVENTION
According to the first aspect of the present invention, there is provided a method of leveling strips, which comprises the steps of (i) rectifying a strip by tensioning and bending it with a tension leveler, the load acting on the strip being 70% or more of the yield, or proof, stress of the strip and (ii) rectifying the strip by tensioning it with a roller leveler, the tension acting on the strip being 50 N/mm
2
or less.
According to the second aspect of the present invention, there is provided a leveling equipment of strips, which comprises (i) entry bridle rollers, center bridle rollers, and exit bridle rollers, (ii) a tension leveler disposed between the entry bridle rollers and the center bridle rollers, and (iii) a roller leveler disposed between the center bridle rollers and the exit bridle rollers.
According to the third aspect of the present invention, there is provided the leveling equipment of strips, wherein the diameters of the rollers of the tension leveler are 450 or more times the thickness of a strip to be rectified.
The advantages offered by the first aspect of the invention are as follows. By applying a load of 70% or more of the yield, or proof, stress of a strip while it is going through the tension leveler, the development of residual stress in the strip can be suppressed. Besides, by applying tension of 50 N/mm
2
or less to the strip while it is going through the roller leveler, the residual stress in the strip developed in the tension leveler can be reduced.
The advantage offered by the second aspect of the invention is as follows. While a strip is being rectified with the tension leveler, a load of 70% or more of the yield, or proof, stress of the strip can be applied to it with the entry and center bridle rollers. Then, while the strip is being rectified with the roller leveler, the tension acting on the strip can be adjusted to 50 N/mm
2
or less with the center and exit bridle rollers. Thus, the leveling method of the first aspect of the invention can be implemented.
The advantage offered by the third aspect of the invention is as follows. Because the radius of curvature of a strip on each roller in the tension leveler is large, a load of 70% or more of the yield, or proof, stress of the strip can be applied to it.


REFERENCES:
patent: 3777532 (1973-12-01), Noe
patent: 3924428 (1975-12-01), Noe
patent: 4651549 (1987-03-01), Masui
patent: 5161400 (1992-11-01), Lefor

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