JPH05279823A - Phosphor bronze bar scarcely causing wear to stamping die - Google Patents

Abstract

PURPOSE:To provide a phosphor bronze bar scarcely causing wear to a die for working. CONSTITUTION:In a phosphor bronze bar having a composition consisting of 0.8-10% Sn, 0.01-0.4% P, and the balance Cu with inevitable impurities, the crystalline grain in the surface structure of this bar has an elongate shape elongated in a rolling direction. When (a) and (b) represent the average minor axis and the average major axis of the elonged crystalline grain, respectively, (a) is 5 to 25mum, (b) is 7 to 170mum, and b/a is 1.4-6.7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phosphor bronze strip material which is less likely to wear a working die.

[0002]

2. Description of the Related Art The composition of phosphor bronze is Sn: wt%.
0.8 to 10%, P: 0.01 to 0.4%, the rest consisting of Cu and unavoidable impurities. This phosphor bronze strip material is generally excellent in spring property and is therefore often used for spring parts. It is well known that it is used.

This phosphor bronze strip material is obtained by casting a phosphor bronze ingot by a horizontal continuous casting machine to remove scales on the surface of a phosphor bronze thick plate, and then repeatedly performing cold rolling and annealing to obtain a final cooling. Manufactured by hot rolling. In this case, in order to improve the spring property of the phosphor bronze strip, the size of the crystal grains obtained by the final annealing is controlled to an average grain size of less than 5 μm, and the size of the crystal grains obtained by the final cold rolling is averaged. Grain width: less than 5 μm, and has a shape in which crystal grains are extended in the rolling direction according to the rolling rate (hereinafter, this shape is referred to as a stretched shape).

Since such a phosphor bronze strip is excellent in toughness, it has recently come to be used for manufacturing electric and electronic parts such as light, thin, short and small household electric appliances.

[0005]

However, when an attempt is made to stamp the phosphor bronze strip made of crystal grains having the above-mentioned conventional drawn shape to manufacture electrical and electronic parts, the stamping die is worn out greatly and the die Since the shape and accuracy of the product are adversely affected by the abrasion of the mold, it is necessary to frequently modify or replace the mold, which causes a cost increase of electric and electronic parts.

Therefore, it is possible to use a phosphor bronze strip having an annealed structure as-annealed without final cold rolling, but a phosphor bronze strip having such an annealed structure is inferior in strength.
Since the elongation is large, there is a problem that the wear of the stamping die is rather large and the strength required for electric and electronic parts is insufficient.

[0007]

Therefore, the present inventors have
As a result of conducting research to develop a phosphor bronze strip material in which the die wear during stamping is small and the strength and toughness of stamped products are fully satisfactory as electrical and electronic parts, phosphor bronze casting with normal composition A lump is cast by a horizontal continuous casting machine, chamfered, then repeatedly cold rolled and annealed,
The phosphor bronze strip obtained by adjusting the average grain size in the annealing before the final cold rolling and the rolling rate in the final cold rolling is less likely to wear the stamping die, and the strength and We have obtained the knowledge that sufficient toughness can be ensured.

The present invention has been made on the basis of such findings, and in terms of weight%, Sn: 0.8 to 10%,
P: 0.01-0.4% is contained, and the phosphor bronze strip having the composition of the balance Cu and unavoidable impurities,
The crystal grains of the surface texture of this strip show a stretched shape, and when the average minor axis of the stretched crystal grains is a and the average major axis is b, a: 5 to 25 μm, b: 7 to 170 μm, 1.4 ≦ It is characterized by a phosphor bronze strip material that is less likely to wear a stamping die having a size of b / a ≦ 6.7.

The phosphor bronze strip material according to the present invention, which is less likely to wear the stamping die, is obtained by first casting a phosphor bronze ingot having a predetermined composition by a horizontal continuous casting machine, chamfering it, and then cold rolling and annealing. Repeatedly, the average grain size is adjusted to 5 to 25 μm in the annealing before the final cold rolling, and the rolling rate of the final cold rolling is rolled within the range of 30 to 85%.

Since the conventional phosphor bronze strip material is adjusted to have an average grain size of less than 5 μm in the annealing before the final cold rolling, the surface texture obtained after the final rolling is the surface texture of the phosphor bronze strip material obtained by the present invention. Compared with, the size of the crystal grain is necessarily different.

Next, the reasons why the composition of the phosphor bronze strip of the present invention and the crystal grain size of the surface texture are limited as described above will be explained.

(1) Sn Sn has an action of improving strength, but if the content of Sn is less than 0.8%, the desired effect cannot be obtained. On the other hand, 10%
If it is contained in excess of 0.1%, the strength improvement tends to be saturated, so the content was set to 0.01 to 0.4%.

(2) Pp has a deoxidizing action during melting and casting, but if it is less than 0.01%, it has no declining effect, and if it exceeds 0.4%, the deoxidizing action tends to saturate. Therefore, the content is set to 0.01 to 0.4%.

(3) Crystal Grains The crystal grains on the rolled surface of the phosphor bronze strip of the present invention show a stretched shape. If the average minor axis a of the stretched crystal grains is less than 5 μm, the stamping die wear is sufficiently reduced. No effect is obtained, while the average minor axis a of the drawn crystal grains is 25 μm.
If it exceeds, it is not preferable because the surface becomes rough during the bending process of the part, and therefore a: 5 to 25 μm is set. The average major axis b of the drawn crystal grains is 170 μm.
If the average major axis b is less than 7 μm, the rolling ratio becomes relatively low and the desired strength cannot be obtained. : 7 to 170 μm.

Further, the average major axis of the stretched crystal grains /
If the value of the average minor axis (b / a) exceeds 6.7, the metal structure becomes a completely rolled structure and wear of the stamping die is increased, which is not preferable, while the value of b / a is 1. If it is less than 4, sufficient strength cannot be obtained, which is not preferable.

Even if the flatness is improved by the tension leveler after the final rolling, the stress strain is removed by the tension annealer or the batch type annealing furnace, or the quality characteristics are improved by the combination of these two treatments, the purpose of the present invention is impaired. is not.

[0017]

EXAMPLE A phosphor bronze having the composition shown in Table 1 was prepared,
These phosphor bronze are melted by using a coreless type induction melting furnace, and then by horizontal continuous casting method, thickness: 18 mm, width: 4
An ingot having a dimension of 50 mm was obtained. S of the above ingot
A phosphor bronze ingot of n: 8% or more was homogenized and annealed at 700 ° C.

The surface of the obtained phosphor bronze ingot was set to 0.
Both sides of 5 mm were machined to obtain a machined coil with a thickness of 17 mm. Then, this coil was repeatedly subjected to cold rolling and annealing, and finally annealed under the conditions shown in Table 1
A final annealed strip having the average crystal grain size shown in Table 1 was produced.

The final annealed strips are further subjected to final cold rolling at the rolling ratios shown in Table 1, and the strips of the present invention 1 to 10 having a thickness of 0.25 mm, the comparative strips 1 to 5 and the conventional strips. 1 to
2 was produced.

[0020]

[Table 1]

The strips 1 to 1 of the present invention thus obtained
0, the values of the average minor axis a, the average major axis b and b / a of the drawn crystal grains on the surfaces of the comparative strips 1 to 5 and the conventional strips 1 and 2 are measured, and the measurement results are shown in Table 2. At the same time, the above-mentioned strips 1 to 10 of the present invention, comparative strips 1 to 5 and conventional strips 1 and 2 are respectively used by using a WC-Co type cemented carbide die.
Punching a rectangle with a length of 1.0 mm and a width of 2.0 mm at a speed of 600 strokes per minute, measuring the amount of wear of the mold when the number of strokes reaches 1 million times, and the results are shown in Table 2. Indicated.

[0022]

[Table 2]

[0023]

From the results shown in Tables 1 and 2, it can be seen that the strips 1 to 10 of the present invention are much less likely to wear the die during stamping as compared with the conventional strips 1 and 2. Further, the comparative strips 1 to 5 which are out of the range of the present invention (values out of the range of the present invention are marked with * are shown in Table 2) are those having a large amount of wear of the mold or the metal. It can be seen that even if the amount of die wear is small, it exhibits unfavorable properties as an electric or electronic component shown in the remarks.

As described above, when the phosphor bronze strip material of the present invention is stamped to produce electric and electronic parts, the number of times of exchanging the mold can be reduced, so that the cost can be remarkably reduced and the industrial It has excellent effects.

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[Procedure amendment]

[Submission date] May 11, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

When a lead frame is trial-produced using the phosphor bronze strip of the present invention, a lead frame band in which a plurality of units of lead frames are connected from the phosphor bronze strip is produced by etching, and the lead of this plurality of units is formed. Although it is also possible to cut a lead frame band in which frames are connected to each other to produce a lead frame for each unit, the phosphor bronze strip material of the present invention also has an effect that the cutting edge used for such cutting is extremely less worn. is there. As described above, when the phosphor bronze strip material of the present invention is stamped or cut to manufacture electric and electronic components, the number of times of exchanging the mold or the cutting edge can be reduced, so that the cost can be significantly reduced, It has excellent industrial effects.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junichi Kumagai 128-7 Ogimachi, Aizuwakamatsu, Fukushima Prefecture Wakamatsu Works, Mitsubishi Shindoh Co., Ltd.

Claims (1)

[Claims] 1. By weight%, Sn: 0.8-10%, P:
In a phosphor bronze strip containing 0.01 to 0.4% and the balance being Cu and unavoidable impurities, the crystal grains of the surface texture of this strip have a shape elongated in the rolling direction (hereinafter, This shape is referred to as a stretched shape, and when the average minor axis of the crystal grains having this stretched shape is a and the average major axis is b, a: 5 to 25 μm, b: 7 to 170 μm, 1.4 ≦ b / A phosphor bronze strip material which is less likely to wear a stamping die, which has a dimension of a ≦ 6.7.