WO2013136772A1

WO2013136772A1 - Wire rod softening device

Info

Publication number: WO2013136772A1
Application number: PCT/JP2013/001606
Authority: WO
Inventors: Hideki Kawaguchi; Hidenaga HIYOSHI
Original assignee: Yazaki Corporation
Priority date: 2012-03-14
Filing date: 2013-03-12
Publication date: 2013-09-19
Also published as: TW201343277A; MX2014011035A; CN104204239A; PH12014501998A1; JP2013189685A; JP6063134B2

Abstract

The present invention provides a copper wire rod softening device which can stably soften a copper wire over a broad range from low speed area to high speed area. The copper wire (2) is guided to first, second and third electrode sheaves (31, 32, 33), and moved. A power supply (5) supplies AC voltage between the first and second electrode sheaves (31, 32), and between the second and third electrode sheaves (32, 33). Electrical current is applied to the copper wire (2), and thereby the copper wire (2) is softened. The power supply (5) consists of an inverter. The inverter has a converter portion transforming AC voltage into DC voltage, and an inverter portion transforming the DC voltage transformed by the converter portion into AC voltage.

Description

WIRE ROD SOFTENING DEVICE

The present invention relates to a wire rod softening device, in particular, a wire rod softening device having a plurality of electrode sheaves to which a wire rod is guided, and a power supply supplying AC voltage between the electrode sheaves so that an electric current is applied to the wire rod coming into contact with the electrode sheaves and moving between the electrode sheaves so as to soften the wire rod.

In general, a thin wire rod, for example a thin copper wire is formed by drawing a thick copper wire with a wiredrawing machine. Since the formed thin copper wire is processed by drawing, the thin copper wire is a hard copper wire. The hard copper wire is literally hard, and thereby has excellent mechanical characteristic. In contrast, elasticity, flexibility, electric conductivity and so on are inferior.

For this reason, many of the hard copper wires are heat-treated to an appropriate temperature, slowly cooled, softened, and then they are used. In this manner, the wire rod softening device for softening the copper wire guides the copper wire to a plurality of electrode sheaves, brings the copper wire into contact with the electrode sheave, and moves the copper wire. Furthermore, by applying AC (Alternating-Current) voltage between the electrode sheaves, an electric current is applied to the copper wire, and thereby the copper wire is softened (for example, PTL 1). Generally, supply source of the AC voltage is used for commercial AC source. The frequency thereof is 50 Hz, the voltage is 200 V, and they are fixed.

As a result, as shown in FIG. 4, in a conventional softening device, there is a problem such that AC voltage can not be supplied to the copper wire moving between the electrode sheaves for enough time in a high-speed area that moving speed between the electrode sheaves of the copper wire is fast. Thereby the copper wire can not be softened by lack of heating of the copper wire. Furthermore, AC voltage having enough frequency can not be supplied to the copper wire. Therefore, AC voltage phase difference is caused when passing the electrode sheave, and thereby change in the quantity of heating becomes large. Thus, softening of the copper wire is not stabilized. FIG. 4 is a graph showing stretch rate of the copper wire when commercial AC source fixed with the frequency of 50 Hz and the voltage of 200V is supplied between the electrode sheaves, and moving speed of the copper wire is varied in the range of 50 m/min - 1000 m/min.

In an example shown in FIG. 4, when moving speed becomes fast, the stretch rate of the copper wire varies widely. Furthermore, when the moving speed is 1000 m/min, supply frequency of AC voltage is 5.1 parts as shown in the following formula (1). When the moving speed is over 1000 m/min, 5 parts of stabilized frequency for softening can not be ensured. Thus, the copper wire can not be stably softened. Here, the stabilized frequency for softening means a frequency that the stretch rate of the copper wire varies widely when the supply frequency is equal or lower than the stabilized frequency, and the minimum value is equal or lower than the standard value.
Supply frequency = copper wire length between the electrode sheaves / moving speed * frequency of AC voltage = 1700 mm / 16667 mm/sec (= 1000m/min) * 50 Hz = 5.1 parts ----- (1)

Furthermore, in a low-speed area that moving speed between the electrode sheaves of the copper wire is slow, AC voltage is oversupplied to the copper wire. As a result, since the copper wire is excessively heated, the copper can not be softened. In order to solve the above problem, conventionally as shown in FIG. 5, by using a thyristor, a shaded area of AC voltage is cut and voltage is controlled so as to prevent excessive heating for the copper wire (PTL 2). However, in voltage control with the use of the thyristor, there is no a potential difference in A section shown in FIG. 5, and electric current does not flow. For this reason, heat is no produced in the A section. Therefore, heating is not enough in the A section, and thereby softening of low-speed area is not performed. In the example shown in FIG. 4, when the moving speed is equal to or less than 200 m/min, softening can not be performed.

[PTL 1] Japanese Patent Application No. 2000-313922
[PTL 2] Japanese Patent Application No. 2002-275530

Accordingly, the present invention is to provide a wire rod softening device which can stably soften a copper wire over a broad range from low-speed area to high-speed area.

In order to attain the above object, according to a first aspect, there is provided a wire rod softening device comprising, a plurality of electrode sheaves to which a wire rod is guided; and a power supply supplying AC voltage between the electrode sheaves so that an electric current is applied to the wire rod moving in contact with the electrode sheaves and thereby the wire rod is softened. The power supply consists of an inverter, and the inverter has a converter portion transforming the AC voltage into DC voltage and an inverter portion transforming the DC voltage transformed by the converter portion into AC voltage.

Preferably, according to a second aspect, the wire rod softening device further comprises a voltage regulator controlling the inverter depending on moving speed between the electrode sheaves of the wire rod and thereby adjusting the voltage of the AC voltage transformed by the inverter portion.

According to the present invention of the first and second aspects, AC voltage is transformed into DC voltage by the converter portion, and the DC voltage transformed by the converter portion is transformed into AC voltage. Therefore, the voltage of the AC voltage supplied between the electrode sheaves can be adjusted, and the frequency thereof can be transformed into the frequency higher than the frequency of the original AC voltage. Thus, softening can be stably performed in a range from a low-speed area to a high-speed area, and variability of the stretch rate of the wire rod can be prevented compared with a conventional device.

FIG. 1 is a sectional-view of main part showing an embodiment of a wire rod softening device of the present invention. FIG. 2 is an electric configuration diagram showing the details of power supply shown in FIG. 1. FIG. 3 is a graph showing stretch rate of copper wire to moving speed of the copper wire in the wire rod softening device shown in FIG. 1. FIG. 4 is a graph showing stretch rate of copper wire to moving speed of the copper wire in a conventional wire rod softening device. FIG. 5 is a graph showing AC voltage supplied between electrode sheaves when voltage control is performed by using a conventional thyristor.

A wire rod softening device of the present invention will be explained with reference to FIGS. 1 and 2. FIG. 1 is a sectional-view of main part showing an embodiment of the wire rod softening device of the present invention. FIG. 2 is an electric configuration diagram showing the details of power supply shown in FIG. 1. As shown in FIG. 1, the wire rod softening device 1 has first, second, and third electrode sheaves as an electrode sheave to which AC voltage is applied from a power supply 5 described below, a plurality of

sheaves

41, 42, 43, 44, 45 for adjusting tension to a copper wire 2 as a wire rod is guided, the power supply 5, control device 6 as a voltage regulator controlling the power supply 5 and a tank 7 for cooling the copper wire 2 in which the second electrode sheave 32 is arranged. The power supply 5 applies AC voltage between the first electrode sheave 31 and the second electrode sheave 32, and between the second electrode sheave 32 and the third electrode sheave 33, and thereby an electric current is applied to the copper wire 2 moving between the first electrode sheave 31 and the second electrode sheave 32, and between the second electrode sheave 32 and the third electrode sheave 33. As a result, the copper wire 2 is softened.

The first and

second electrode sheaves

31, 32 are arranged next to each other in a vertical direction. The first and

third electrode sheaves

31, 33 are arranged next to each other in a horizontal direction. The sheave 41 is positioned at lead-in wire side of the first electrode sheave 31. The

sheaves

42 and 43 are arranged between the second electrode sheave 32 and the third electrode sheave 33, and located next to each other in the vertical direction. The

sheaves

44 and 45 are arranged at lead-out wire side of the third electrode sheave 33, and located next to each other in the vertical direction.

The copper wire 2 led into the wire rod softening device 1 is guided in order of the lower side of the sheave 41, the upper side of the first electrode sheave 31, and the lower side of the second electrode sheave 32. Furthermore, the copper wire 2 is again guided to the upper side of the first electrode sheave 31, and then is guided in order of the lead-out wire side of the sheave 42, the lower side of the sheave 43, the lead-in wire side of the sheave 42, the upper side of the third electrode sheave 33, the lead-out wire side of the sheave 44, the lower side of the sheave 45, and the lead-in wire side of the sheave 44. Thereafter, the copper wire 2 comes out from the wire rod softening device 1.

According to the above wire rod softening device 1, the copper wire 2 moving between the first electrode sheave 31 and the second electrode sheave 32 is heated by supplying AC voltage, and then cooled by the tank 7. As a result, the copper wire 2 is softened. That is, an interval between the first electrode sheave 31 and the second electrode sheave 32 is a softening zone of the copper wire 2. The copper wire 2 contacting between the second electrode sheave 32 and the third electrode sheave 33 is heated by supplying AC voltage, and thereby water attached to the copper wire 2 is dried. That is, an interval between the second electrode sheave 32 and the third electrode sheave 33 is a drying zone of the copper wire 2.

As shown in FIG. 2, the above power supply 5 has an inverter 51 and a transformer 52. The inverter 51 has a converter portion 51A transforming AC voltage from a commercial AC source 8 into DC (direct-current) voltage, and an inverter portion 51B transforming the DC voltage transformed with the converter portion 51A into AC voltage. Furthermore, the power supply 5 can adjust the frequency and height of the AC voltage outputted from the inverter portion 51B. Also, in the inverter 51 used for the embodiment of the present invention, the frequency can be adjusted between 50 Hz and 3 kHz. As this inverter 51, a current source inverter and a voltage source inverter are well-known.

In the inverter 51 of current source type, for example, the converter portion 51A consists of a thyristor rectifier and a smoothing reactor, and can adjust the height of the transformed DC voltage. The inverter portion 51B switches variable DC voltage, and thereby a pulsed pseudo sinusoidal wave is generated. By adjusting the frequency of the pulse, the frequency of the sinusoidal wave can be adjusted, and by adjusting the duty of the pulse the height of the AC voltage can be adjusted. In other words, the inverter 51 of the voltage source type can adjust the frequency and height of the AC voltage with the inverter portion 51B.

On the other hand, in the inverter 51 of voltage source type, for example, the converter 51A consists of a diode rectifier and a smoothing condenser, and the height of the transformed DC voltage is constant. The inverter portion 51B switches DC voltage, and thereby a pulsed pseudo sinusoidal wave is generated. By adjusting the frequency of the pulse, the frequency of the sinusoidal wave can be adjusted, and by adjusting the duty of the pulse the height of the AC voltage can be adjusted. In other words, the inverter 51 of the voltage source type can adjust the frequency and height of the AC voltage with the inverter portion 51B.

The above transformer 52 transforms the AC voltage outputted from the inverter 51, and supplies the transformed voltage to the first, second and third electrode sheaves 31, 32, 33.

The control device 6 controls AC voltage so that the frequency of the AC voltage outputted from the inverter 51 is higher than the frequency of the AC voltage outputted from the commercial AC source 8. For example, when the frequency of the commercial AC source 8 is 50 Hz, the control device 6 controls the AC voltage so that the AC voltage of 300 Hz is outputted from the inverter 51. Thereby, if the moving speed is 1200 m/min, supply frequency of the AC voltage for the copper wire 2 can be 27 parts as shown in the following formula (2). As a result, the copper wire can be steady softened in high-speed area.
Supply frequency = copper wire length between the first electrode sheave 31 and the second electrode sheave 32 / moving speed * frequency of AC voltage outputted from the inverter 51 = 1700 mm / 16667 mm/sec * 300 Hz = 30.6 parts ----- (2)

In addition, the control device 6 acts as a voltage regulator, and controls AC voltage so as to increase the height of the AC voltage outputted from the inverter 51 as the moving speed of the copper wire 2 becomes quickly. Furthermore, the control device 6 controls the AC voltage so as to reduce the height of the AC voltage outputted from the inverter 51 as the moving speed becomes slowly.

Next, the inventors measured stretch rate (%) of the copper wire 2 when the moving speed of the copper wire 2 is changed from 50 m/min to 1200 m/min, and checked the effect of the present invention. The result is shown in FIG. 3. When the moving speed is 50 m/min, the AC voltage is adjusted so that the frequency of 70 Hz and the height of 9 V are outputted from the inverter 51. Furthermore, when the moving speed is 200 m/min, the AC voltage is adjusted so that the frequency of 70 Hz and the height of 19 V are outputted from the inverter 51. When the moving speed is 400 m/min, the AC voltage is adjusted so that the frequency of 70 Hz and the height of 28 V are outputted from the inverter 51. When the moving speed is 600 m/min, the AC voltage is adjusted so that the frequency of 70 Hz and the height of 35.5 V are outputted from the inverter 51. When the moving speed is 800 m/min, the AC voltage is adjusted so that the frequency of 70 Hz and the height of 41 V are outputted from the inverter 51. When the moving speed is 1000 m/min, the AC voltage is adjusted so that the frequency of 70 Hz and the height of 46 V are outputted from the inverter 51. When the moving speed is 1200 m/min, the AC voltage is adjusted so that the frequency of 70 Hz and the height of 50 V are outputted from the inverter 51.

As can be seen in FIG. 3 compared with FIG. 4, variability of the stretch rate (%) of the copper wire 2 can be prevented by adjusting the AC voltage so that the frequency of the AC voltage outputted from the inverter 51 is higher than the frequency of the AC voltage outputted from the commercial AC source 8. Furthermore, even if the moving speed is 1200 m/min in the high-speed area, softening can be stably performed. Moreover, by adjusting the AC voltage so that the height of the AC voltage outputted from the inverter 51 becomes small as the moving speed is slowly, even if the moving speed is 50 m/min in the low-speed area, softening can be steady performed.

According to the above embodiment, the arrangement of the first, second, and third electrode sheaves 31, 32, 33 is positioned as shown in FIG. 1, but the present invention is not limited thereto. For example, the arrangement of the first, second and third electrode sheaves 31, 32, 33 may be positioned so that the copper wire 2 can be guided.

Furthermore, according to the above embodiment, the copper wire as a wire rod is used, but the present invention is not limited thereto. For example, various wires required to softening may be used.

The illustrated embodiments of the present invention have been described for illustrative purposes only, and not by way of limiting the invention. Accordingly, the present invention can be implemented with various modifications made thereto within the scope of the present invention.

1 wire rod softening device
2 copper wire (wire rod)
5 power supply
6 control device (voltage regulator)
51 inverter
51A converter portion
51B inverter portion
31 first electrode sheave (electrode sheave)
32 second electrode sheave (electrode sheave)
33 third electrode sheave (electrode sheave)

Claims

A wire rod softening device comprising,
a plurality of electrode sheaves to which a wire rod is guided; and
a power supply supplying AC voltage between the electrode sheaves so that an electric current is applied to the wire rod moving in contact with the electrode sheaves and thereby the wire rod is softened,
wherein the power supply consists of an inverter, and the inverter has a converter portion transforming the AC voltage into DC voltage and an inverter portion transforming the DC voltage transformed by the converter portion into AC voltage.
The wire rod softening device according to claim 1, further comprising a voltage regulator controlling the inverter depending on moving speed between the electrode sheaves of the wire rod and thereby adjusting the voltage of the AC voltage transformed by the inverter portion.