JPH02163330A - Annealed copper wire for hammering piano string - Google Patents

Abstract

PURPOSE:To provide the wire which is easily softened at relatively low temp. and has sufficient required ductility by applying heat treatment to an annealed copper wire composed of an oxygen free copper-base dilute alloy with a specific composition. CONSTITUTION:An annealed copper wire composed of an oxygen free copper- base dilute alloy having a composition which contains, by weight, 0.001-0.05%, in total, of at least one or >=2 kinds among Nb, Ti, Zr, Hf, V, Ta, Fe, B, and misch metal and in which the total content of inevitable impurities, such as oxygen, is regulated to <=0.005wt.% is heat-treated so that SEN indicating ductility is regulated to >=350mm. The elements, such as Nb and Ti, form compounds together with the elements, such as P and S, existing in the form of solid solution in the oxygen free copper matrix and raising softening temp. and remove the above compounds by precipitation. As a result, the softening temp. of the oxygen free copper can be remarkably reduced, and the wire having superior ductility, excellent in bending resistance and fatigue resistance, and having high soundness can be obtained at low annealing temp., and further, the annealed copper wire for hammering piano string capable of maintaining superior tone quality over a long period can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an annealed copper wire useful for striking piano strings.

[Prior Art] Strings made of piano wire wrapped with annealed copper wire are used to string the bass part of a piano.

Tough pitch steel containing about 0.05wt% oxygen is generally used for this annealed copper wire, and is drawn to a diameter of about 1.0 to 1.6nw+ at a processing rate of less than 95%, and
It is used after being annealed and softened at a temperature of ~400°C.

[Problems to be Solved by the Invention] In order to process the winding around the struck string, if the wire is not sufficiently softened, the processability will be poor, and the resulting product will have a poor tone due to springback. Become. For this reason, it is necessary to sufficiently soften the annealing process and retain sufficient flexibility, which requires raising the annealing temperature and lengthening the annealing time, resulting in an overall cost increase. There is a strong demand for materials that soften easily at lower temperatures.

On the other hand, the tough pitch steel is 0.05w as described above.
Since the copper matrix contains about 1.5 t% of oxygen, this oxygen has the effect of precipitating impurities in the copper matrix, especially impurities that increase the softening temperature, in the form of oxides and cleaning the matrix. It has the characteristic of being easily softened.

However, on the other hand, a large amount of suboxide %1 (CuzO) precipitated phase (
There is a problem in that the above-mentioned winding properties (particularly common in grain boundaries) are easily embrittled when annealed at high temperatures to obtain the above-mentioned sufficient flexibility, and the bending properties and fatigue resistance properties are significantly deteriorated. Internal defects may occur due to vibrations during work or use, which may adversely affect the string's characteristics and deteriorate the sound quality.

Oxygen-free steel contains only oxygen of around 10111111, and embrittlement due to the presence of cuprous oxide does not occur, or on the other hand, it has the effect of precipitating and removing elements that are dissolved in the matrix and increase the softening temperature. Due to the lack of copper, the softening temperature is considerably higher than that of tough pitch copper, making it difficult to obtain the aforementioned highly flexible oxygen-free wire.

In view of the above-mentioned circumstances, the object of the present invention is to provide a piano that can be easily softened at relatively low temperatures, has sufficient flexibility, and has excellent bending and fatigue resistance. The purpose is to provide an oxygen-free copper wire for strings.

[Means for Solving the Problems 1] The present invention provides Nb, 'I'i, Zr, Hf, V, 1'
Contains a total of 0.001 to 0.05 wt% of at least one or two or more of aFe, B, and Mitsushi metal,
It is made of an oxygen-free copper-based dilute alloy with a total of 0.005 wt% or less of unavoidable impurities such as oxygen, and exhibits flexibility.
It is characterized by being heat-treated so that NIJlbOr> is 350+n+ or more.

As the additive element, it is preferable to select one or more of the above-mentioned elements and contain the total o, oot to 0.05 wt%, and if it is 0.001 wt% or less, sufficient improvement in suppleness is not achieved. If the amount exceeds 0.05 wt%, the amount of added elements will increase, and the effect will be reversed, not only deteriorating the flexibility but also increasing the softening temperature. Undesirable.

In addition, in order for the mild steel wire according to the present invention to exhibit desired characteristics, it is desirable that impurities such as oxygen that inevitably exist in oxygen-free steel be as small as possible, and the total amount of impurities should be 0.005 wt% or less. It is desirable that the amount of oxygen be 0.0021 t% or less, otherwise this oxygen will react with additive elements such as Nb, which will reduce the matrix purification effect required of the additive elements. There is no improvement in suppleness.

[Operation] Elements such as Nb and "r"i form a compound with elements such as P and S, which are dissolved in the -V-oxygen copper matrix and increase the softening temperature, and are precipitated and removed. As a result, the softening temperature of P7# oxygen steel can be significantly lowered, and a highly sound wire rod with excellent flexibility, good bending resistance and fatigue resistance can be obtained at a low annealing temperature. It is possible to obtain an annealed copper wire for piano strings that can maintain good sound quality.

[Example] The present invention will be described below with reference to Examples.

Additional elements in the amount shown in Table 1 in the form of a copper master alloy are added to the molten oxygen-free steel melted in a continuous melting and casting device to produce an ingot of 20 On+sa diameter made of a dilute copper alloy based on oxygen-free copper. On the other hand, ingots of the same diameter were obtained from tough pitch copper melted in a shaft furnace, and each ingot was hot extruded to a diameter of 111w1+ in accordance with a conventional method. These wire rods were subjected to cold drawing without adding a stripping process, and were finished to a diameter of 1.0 mm. Thereafter, these drawn wire materials were annealed at a temperature of 400° C., and sample 1 was prepared for flexibility measurement.

Measurement of suppleness is F, Schi 1ckhe
SEN < 5 Or, which was proposed by R et al. and is currently considered the most appropriate method for determining suppleness.
inQE IQngation NuIlber)
Based on the above.

In this method, the gauge point of a sample cut to a length of 1300 cm is set at 1
1000a, 0,7k2/tm2(0
, 55 kg) and tightly wound it around a mandrel (diameter 10 cm) that is 10 times the diameter of the wire to make a coil.

The coil is hung vertically and weighed again at 0.7 kg/1
Add a weight of 1 m+2, lower it at a speed of 50 cm/sec or less, and hold it there for 2 minutes. After that, the coil is left to stand naturally on a flat surface, the gage length of the coil is measured after 1 minute, and the value in units of seams obtained by subtracting the origin distance (29 nm) of the coil that was first tightly wound is defined as SEN. be.

Table 1 shows the SEN of each sample thus obtained.

The alloy composition range of the present invention, N015-14, is the conventionally used I
It can be seen that the SEN is 50 to 80 nodes larger in all cases than in the case of the tough pitch jllI (No, 1>), which is an extremely flexible @ line.

Usually -1! ! 0.0002 to 0.0003 for oxygen copper
Wt% of P and 0°0005 to 0.001wt% of S are dissolved in solid solution, and it is thought that these trace impurities deteriorate the SEN of oxygen-free steel as described above, and the present invention By adding alloying elements such as Nb, these alloying elements combine with the impurities and change them from a solid solution state to a precipitated state, thereby making the matrix extremely pure,
This is considered to be due to improved SEN.

Oxygen-free copper itself without adding alloying elements according to the present invention (
No. 2) has a total amount of unavoidable impurities of 0.005w
Although the purity was very high at t% or less, the SEN was still small, and even if alloying elements were added, N013 was lower than the range specified by the present invention and N014 was higher than the specified range. However, the SEN is small and does not reach the target of 350 of the present invention.In other words, if the amount added is small, the purification effect of the matrix will be insufficient, but if the amount exceeds the specified range, the added element itself will reduce the SEN. This can be thought to be due to the effect of causing

Table ■ [Effects of the invention] As described above, according to the oxygen-free steel dilute alloy according to the present invention,
It is possible to obtain annealed copper wire with great flexibility without sacrificing productivity, and it is much easier to wrap around for piano strings, and it also has excellent bending resistance and fatigue resistance. As a result, it is possible to achieve a significant effect of significantly improving the tone of the piano and maintaining it for many years.

Claims (1)

[Claims] (1) Nb, Ti, Zr, Hf, V, Ta, Fe, B,
Consisting of an oxygen-free copper-based dilute alloy containing a total of 0.001 to 0.05 wt% of at least one or two or more misch metals and a total of 0.005 wt% or less of unavoidable impurities such as oxygen, SEN (So
Annealed copper wire for piano strings that is heat-treated so that the ring elongation number is 350 mm or more.