JPH05155415A - Steel tape - Google Patents

Abstract

PURPOSE:To prolong a bending fatigue life of a steel tape having a curved cross section. CONSTITUTION:By utilizing the fact that when a tape is thinned like a plate spring, for example, bending stress becomes small, plate thickness is made gradually thinner toward both end parts from the center in the width direction of a steel tape 1 whose cross section in the width direction is curved, so that a stress value in the width direction generated on both end parts at the time of bending becomes small and a bending fatigue life can be thereby elongated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel tape used for a conveyor belt of a conveyor for conveying banknotes, silicon wafers, and the like, and more particularly to a steel tape for increasing the repeated bending fatigue strength in the longitudinal direction thereof. Regarding

[0002]

2. Description of the Related Art As is well known, a typical steel tape is, for example, a convex steel tape. This is intended to prevent the convex steel tape from being bent in the longitudinal direction by curving the cross section in the width direction and increasing the rigidity in the plate thickness direction.

Utilizing the above-mentioned properties, the convex steel tape can be used not only as a convex rule but also as a conveyor belt for a bill transporting conveyor or a transporting conveyor for transporting thin plates cut from silicon wafers. It is used.

[0004]

By the way, in the case of the convex steel tape according to the conventional example, the plate thickness is constant. Therefore, when it is bent during use, the crown becomes infinite, that is, there is a part that is extended. At the infinite crown portion, biaxial stress is applied in the longitudinal and width directions of the convex steel tape.

In particular, when the bending radius of the convex steel tape is small, repetitive stress exceeding the fatigue strength of the material occurs. Of course, there is a problem to be solved that the fatigue life is short, though it is broken by repeated bending of, for example, about 10 ⁴ to 10 ⁵ , though it depends on the size of the radius of curvature.

By the way, the stress analysis results of the front and back stress states of the convex steel tape which are not bent are shown in FIG. 3 which is a stress explanatory diagram. .. In addition, the symbol t shown in this figure is the plate thickness of the convex steel tape,
σ _w is the stress in the width direction of the convex steel tape, and σ _z is the stress in the longitudinal direction of the convex steel tape.

That is, according to the figure, σ _w is the largest at the center in the width direction, becomes 0 at the end, and σ _w
z is smallest at the center in the width direction and largest at the end. However, when the convex tape exhibiting the stress state as described above is subjected to bending stress, σ _w becomes large even at the end portion in the width direction, and a biaxial stress state is generated, resulting in excessive stress.

Then, in the case of a flat plate member that is subjected to a simple bending stress, for example, a plate spring, the plate thickness is made thin to reduce the bending stress and to prevent the rigidity from decreasing, A method of increasing the plate thickness at both ends is conceivable, but this causes conversely excessive stress to be generated at the end portions rather than at the central portion, so such a cross-sectional shape cannot be adopted.

Therefore, it is an object of the present invention to provide a steel tape having excellent rigidity and resistance to bending fatigue.

[0010]

DISCLOSURE OF THE INVENTION The present invention has been made paying attention to the fact that bending stress can be reduced by reducing the plate thickness, as described in the example of the leaf spring in the preceding paragraph. Therefore, the feature of the configuration of the steel tape according to the present invention is that, in a steel tape having a curved cross section in the width direction, the plate thickness in the width direction increases from the widthwise central portion of the steel tape to the widthwise end portion. It is in the configuration that is gradually thinned.

[0011]

According to the steel tape of the present invention, the plate thickness in the width direction is reduced from the widthwise central portion of the steel tape having the curved widthwise section to the widthwise end portion. Therefore, the stress on the end portion side in the width direction is reduced, while the rigidity is ensured by the bending in the width direction and the plate thickness of the center portion in the width direction.

[0012]

EXAMPLE An example of the steel tape according to the present invention will be described below with reference to FIG. 1 which is an explanatory view of its cross-sectional shape and FIG. 2 which is an explanatory view of a fracture probability. Reference numeral 1 shown in FIG.
Steel tape that is curvedly formed in the width direction at R18 mm and has a thickness of 13 mm at the center in the width direction of 0.14 m.
However, the thickness of both ends is 0.115 m.
m.

The steel tape 1 having such a cross-sectional shape is made of SUS301 material, which is hot die rolling → pickling / shot → solution heat treatment (1000
1050 ° C) → cold rolling (rolling rate 40-60%) →
It is manufactured through a process called convex molding.

On the other hand, through the same steps as above, a conventional constant-strength steel tape having a constant plate thickness of 0.13 mm is manufactured, and the bending fatigue of this and the steel tape 1 according to the present embodiment is determined by a simple winding type. N = 50 using fatigue tester
Was measured and evaluated.

The result is shown in FIG.
According to the figure, in the conventional constant-thickness convex steel tape shown by the broken line, there are some that break at a point exceeding 10 ⁴ , whereas in the steel tape 1 according to this embodiment shown by the solid line, 10 ⁶ Below is not broken at all,
It can be seen that it has a bending fatigue life of 10 times or more as compared with the conventional constant-thickness convex steel tape.

Next, the present embodiment (case 1) in which the widthwise central portion is 0.14 mm and both end portions are 0.115 mm, and the conventional example having a uniform thickness of 0.13 mm ( The stress calculation was performed on three types of steel tapes of case 2), in which the widthwise center portion was 0.115 mm and both end portions were 0.14 mm (case 3).

The results are shown in Table 1 below. However, the rigidity value is an experimental value, and the deformation amount when a constant load is applied is set to 1 for a steel tape of equal plate thickness,
It is shown by the ratio. In addition, σ _{ZL in} Table 1 below
Is the maximum value of the longitudinal stress on the convex side of the steel tape,
σ _ZU is the maximum value of the longitudinal stress on the concave side, and σ _XL
Indicates the maximum stress in the width direction on the convex side.

[0018]

[Table 1]

According to Table 1 above, Case 1, Case 2,
The absolute value of the stress increases in the order of Case 3, and the stress generated in Case 1, that is, the steel tape 1 according to this embodiment is the smallest, so that the bending fatigue life is remarkably higher than in the other two cases. It has been shown to be excellent.

When the thickness of the central portion of the steel tape in the width direction is t _max and the thickness of the end portion is t _min , [(t _max −t _min ) / t _min ] × 100 = 5 ~ 2
It was found that satisfying the condition of 5% is effective for improving the bending fatigue life. By the way, in the case of the steel tape of this embodiment (case 1), t _max = 0.14 mm.
Since t _min = 0.115 mm, ≈22%.

[0021]

As described above in detail, according to the steel tape of the present invention, the plate thickness in the width direction becomes thinner from the center part in the width direction to the end part in the width direction. While rigidity is ensured by the curvature and the plate thickness of the central portion in the width direction, the stress on the end side in the width direction is reduced, so the bending fatigue life is improved compared to the conventional convex steel tape, When it is used as a conveyor belt of a conveyor that conveys banknotes, silicon wafers, etc., it can exert an extremely great effect on the improvement of its reliability.

[Brief description of drawings]

FIG. 1 is a sectional view of the shape of a steel tape according to the present invention.

FIG. 2 is an explanatory diagram of a breakage probability of a steel tape.

FIG. 3 is a stress explanatory diagram of a conventional convex tape.

[Explanation of symbols]

 1 ... Steel tape.

Claims (1)

[Claims] 1. A steel tape having a curved cross section in the width direction, characterized in that the plate thickness in the width direction is gradually reduced from the center portion in the width direction of the steel tape to the end portion in the width direction. Steel tape.