JP2014228459A - Resistance measurement method of aluminum wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resistance measurement method of aluminum wire where stable resistance measurement can be performed while suppressing variation.SOLUTION: In both terminals of aluminum wire 1 comprising a core wire 3 consisting of a plurality of aluminum element wire, a pressure-welding part 2 which is brought in pressure-contact with the plurality of element wire and is integrally joined is formed, and a contact piece of a measuring instrument 20 is brought in contact with the pressure-welding part 2, thereby, electric resistance of the wire is measured.

Description

  The present invention relates to a method for measuring resistance of an aluminum electric wire that can accurately measure the electric resistance of the aluminum electric wire.

  Conventionally, the resistance of an aluminum electric wire for automobiles has been measured by connecting a clip of a resistance tester to both ends of the electric wire.

  Generally, the core wire of the electric wire is composed of a plurality of strands. It is well known that the resistance of an electric wire is measured by joining the core wires at both ends together by soldering and integrating the strands, and regarding the core wire as a single wire conductor (see, for example, Patent Document 1). The resistance of the aluminum wire was measured by connecting a resistance tester clip to the soldered portion of the core wire.

JP 2000-207956 A (paragraph number [0020])

  When soldering the strands of an aluminum wire, if an oxide film is present on the surface of the aluminum strand, the strands are insulated. It is difficult to join a plurality of aluminum wires as a single conductor by soldering. As a result, there has been a problem in that the resistance measurement result of the aluminum electric wire varies.

  In addition, there is a problem that the solder at the soldering portion is easily peeled off, the contact surface with the clip of the resistance measuring device is changed, and accurate resistance measurement cannot be performed.

  In order to eliminate the influence of the oxide film, for example, there is a method of removing the oxide film of an aluminum wire using a flux. However, when flux remains in the soldered portion, there is a problem that the flux affects the resistance value.

  The subject of this invention is providing the resistance measuring method of the aluminum electric wire which suppresses variation and can perform stable resistance measurement.

  The method for measuring resistance of an aluminum electric wire according to the present invention forms a press-contact portion in which a plurality of strands are pressed and integrated in both ends of an aluminum electric wire having a core wire composed of a plurality of aluminum strands, The gist is to measure the electric resistance of an electric wire by bringing a contact of a resistance measuring instrument into contact with the pressure contact portion.

  In the resistance measurement method, the resistance measurement is preferably a four-terminal method.

  In the resistance measurement method, the pressure welding is preferably ultrasonic welding.

  The resistance measurement method for an aluminum electric wire according to the present invention is to form a press-contact portion in which a plurality of strands are press-contacted and integrated at both ends of an aluminum wire, and a contact of a resistance measuring instrument is brought into contact with the press-contact portion By adopting the method of measuring the electrical resistance of the wire, compared to the conventional method of measuring the resistance by joining the strands by soldering and connecting a clip etc. to the soldered part, the strands Can be regarded as a single core wire, so that variations in resistance measurement values can be suppressed and stable resistance measurement can be performed.

FIG. 1 is an explanatory view showing a method for forming a press-contact portion of an aluminum electric wire. FIG. 2 is an explanatory view showing a method for measuring resistance of an aluminum electric wire. FIG. 3 is a graph showing the resistance measurement results of the aluminum electric wire of the example of the present invention. FIG. 4 is a graph showing the resistance measurement results of the aluminum wire of the comparative example.

  Hereinafter, embodiments of the present invention will be described in detail. FIG. 1 is an explanatory view showing a method for forming a press-contact portion of an aluminum electric wire. As shown in FIG. 1, the resistance measurement method for an aluminum electric wire first forms a press-contact portion 2 by subjecting both ends of the aluminum electric wire 1 to press-contact processing. In the aluminum electric wire 1, the core wire 3 is composed of a plurality of strands made of aluminum or an aluminum alloy (hereinafter sometimes referred to as an aluminum strand), and the core wire 3 is covered with a covering material 4 made of an insulator. . The core wire 3 is composed of an assembly of aluminum strands or a strand of aluminum strands.

  In order to form the press contact portions 2 at both ends of the aluminum electric wire 1, a plurality of strands of the core wire 3 are pressed and integrated. Examples of the pressure welding of the core wire 3 include an ultrasonic welding process using an ultrasonic welding apparatus. As shown in FIG. 1, the ultrasonic welding apparatus 10 sandwiches the core wire 5 between the vibrating sound electrode 11 that can vibrate and the cradle 12 and the like, and a light pressure is applied to the core wire 3 by the pressurizing device 13. The vibrator 14 is configured to be able to apply ultrasonic vibration to the vibrating sound electrode 11.

  In the press-contact part 2, the temperature of the contact surface of the aluminum strands of the core wire 3 rises by ultrasonic vibration, and the aluminum strands are joined. In the press-contact portion 2, a plurality of strands are joined and integrated to form a single core wire 3, and the resistance can be stably measured.

  When the press-contact portion is formed by ultrasonic welding, even if an oxide film or the like is present on the surface of the aluminum strand, the oxide coating is removed and the strands can be satisfactorily joined. When the oxide film of the aluminum strand is removed, the pressure contact portion 3 of the core wire 3 can eliminate resistance between the strands and suppress variation in resistance value. Moreover, the method of forming a press-contact part by ultrasonic welding has the advantage that an aluminum electric wire itself is not damaged.

  On the other hand, instead of forming the pressure contact portion 2 on the core wire 3, the conventional method of soldering to the core wire 3 is greatly affected by the oxide film on the surface of the aluminum wire, so that the wires are reliably bonded. It is difficult to integrate. As a result, the measured value of the electrical resistance of the core wire 3 varies.

  Furthermore, since there is no possibility that the solder is peeled off as in the case of soldering, the contact surface 2 formed by ultrasonic welding changes the contact surface when a resistance measuring device clip is connected during resistance measurement described later. There is no risk that accurate measurement will not be possible.

  In FIG. 1, the state which formed the press-contact part 2 in one edge part of the aluminum electric wire 1 was shown. Although not particularly illustrated, a pressure contact portion is also formed on the other end portion of the aluminum electric wire 1 by ultrasonic welding in the same manner as described above.

  FIG. 2 is an explanatory view showing a method for measuring resistance of an aluminum electric wire. As shown in FIG. 2, the resistance measurement method uses an aluminum electric wire 1 having the pressure contact portions 2 formed at both ends, and the Kelvin clips 28 connected to the resistance measuring device 20 at the pressure contact portions 2 and 2 at both ends. 29, the clip is brought into contact with the pressure contact portion 2, and the resistance of the aluminum electric wire 1 is measured. Resistance measurement is performed by the four probe method. The four-terminal method enables accurate measurement in the low resistance region.

  The resistance measuring instrument 20 can be a commercially available device capable of measuring resistance by the four-terminal method. As the contactor, a commercially available Kelvin clip or the like can be used.

  For example, the resistance measuring instrument 20 includes a voltmeter 21, an ammeter 22, a power source 23, and the like as shown in FIG. The resistance measuring instrument 20 includes two current terminals 24 and 27 and two voltage terminals 25 and 26 as connection terminals. Current terminals 24 and 27 and voltage terminals 25 and 26 are connected to Kelvin clips 28 and 29 by lead wires.

  The resistance of the aluminum wire 1 can be measured by applying a predetermined current to the resistance measuring instrument 20 connected to the wire and measuring the voltage value.

  The above-mentioned resistance measurement method for an aluminum electric wire can be used for performance evaluation of the aluminum electric wire. For example, the presence or absence of damage such as a broken wire of an aluminum electric wire can be evaluated. Specifically, it is possible to detect defective products during the manufacture of aluminum wires.

  Further, as described above, the terminal is not connected to the aluminum electric wire 1, the pressure contact portion 2 is formed at both ends of the wire, and the contact is brought into contact with the pressure contact portion 2 to perform resistance measurement, thereby causing an error due to the terminal. It is possible to accurately measure and evaluate the resistance of the wire itself.

  Examples of the present invention and comparative examples are shown below. The present invention is not limited to these examples.

Example 1
Ultrasonic welding was performed on both ends of an aluminum electric wire having a length of 300 mm and a cross-sectional area of 0.35 mm ² to form a press-contact portion. A resistance measuring device clip was connected to the pressure contact portion to measure the resistance of the test specimen. The resistance measurement was repeated 30 times. Table 3 shows the resistance measurement results. In the graph of Table 3, the vertical axis represents the resistance value (unit: mΩ), and the horizontal axis represents the number of measurements. The standard deviation (σ) of the measured values shown in Table 3 was 0.20.

Comparative Example 1
For comparison, the same aluminum wire as in Example 1 was used, the soldering process was performed on the part corresponding to the press contact part, and a resistance measuring device clip was connected to the part, and resistance measurement was performed in the same manner as in Example 1. It was. Table 4 shows the test results. The standard deviation (σ) of the measured values shown in Table 4 was 062. According to the measurement method of Example 1 and Comparative Example 1, according to the method of the present invention, as shown in Example 1, the standard deviation is smaller than that of Comparative Example 1, and it is possible to suppress variations in resistance measurement values. It shows that there is.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

  For example, in the above-described embodiment, an example in which ultrasonic welding is used as the pressure welding method has been shown. However, the pressure welding method may be used as long as it can be pressed and integrated in a state where the aluminum wire is half melted. be able to. Specific pressure welding methods other than ultrasonic welding include resistance welding methods.

DESCRIPTION OF SYMBOLS 1 Aluminum electric wire 2 Pressure welding part 3 Core wire 10 Ultrasonic welding apparatus 20 Resistance measuring device

Claims (3)

  At both ends of an aluminum electric wire having a core wire composed of a plurality of aluminum wires, a pressure contact portion is formed by press-contacting and bonding the plurality of strands, and a contact of a resistance measuring instrument is brought into contact with the pressure contact portion A method for measuring the resistance of an aluminum wire, wherein the electrical resistance of the wire is measured.   The resistance measurement method for an aluminum electric wire according to claim 1, wherein the resistance measurement is a four-terminal method.   The method of measuring resistance of an aluminum electric wire according to claim 1 or 2, wherein the pressure welding is ultrasonic welding.

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