JP5128523B2 - Crimp terminal for high strength thin wire - Google Patents

Description

  The present invention relates to a crimp terminal for a high-strength thin wire used for a wire harness or the like of an automobile.

As countermeasures against recent global warming, automobiles are required to reduce CO ₂ emissions by reducing vehicle weight. On the other hand, in order to meet the needs of safety, comfort, and convenience, the electrical system has been developed with multiple functions and high functions, and the amount of wire harnesses that support these functions tends to increase. For this reason, it is indispensable to reduce the weight of the wire harness in order to reduce the weight of the vehicle, and it is important to develop a technology that makes the electric wire that accounts for less than 70% lighter. One specific measure is to reduce the diameter of the conductor, but it is necessary to improve the strength of the conductor by making it thinner.

  From such a background, instead of the conventional annealed copper wire, a thin copper alloy wire having a high tensile strength such as a Corson alloy wire has begun to be adopted. The tensile strength of the Corson alloy wire used for the thin wire is 1200 MPa, and the tensile strength of the copper alloy that has been used as a terminal material for wire harnesses so far (for example, FAS680 (a copper alloy plate manufactured by Furukawa Electric Co., Ltd.) ) Significantly exceeds the tensile strength of 600 to 700 MPa).

  When the tensile strength of the thin wire is higher than the tensile strength of the terminal material, it is difficult to destroy the oxide film of the thin wire by crimping the terminal, so some measure is required.

  FIG. 9 shows an example of a conventional crimp terminal. The crimp terminal 1 generally has a contact portion 2 with a counterpart terminal, a wire barrel portion 3 that is crimped to a conductor end portion of an electric wire, and an insulation barrel portion 4 that is crimped to an insulating covering end portion of the electric wire. (See Patent Documents 1 and 2). A serration 5 is formed on the inner surface of the wire barrel portion 3. The serrations 5 are formed to break down the oxide film of the conductor by terminal crimping to obtain a good electrical connection state and to increase the crimping strength. The illustrated example is a case where the contact portion 2 is a female type, but the contact portion 2 may be a male type or a tightening terminal type.

  In Patent Document 1, when the serration is formed in an inverted trapezoidal cross-sectional shape and the outer corner is an obtuse angle larger than the inner corner, the shearing force on the conductor of the serration near the end is reduced. It is disclosed that since the damage given to the conductor is reduced, the holding power of the conductor is enhanced and a stable electrical connection state can be obtained.

  In Patent Document 2, the depth of the groove is made different so that the amount of the conductor biting into the groove of the serration is different, and the depth of the groove located closer to the end is made shallower than the groove located closer to the center. Thus, it has been disclosed that the biting of the conductor into the serration groove is made appropriate regardless of the conductor diameter to improve the mechanical and electrical connection performance.

Japanese Patent No. 3343880 Japanese Patent No. 3868234

  Patent Document 1 focuses on reducing conductor damage. However, in the case of a high-strength thin wire, the high-strength thin wire has a higher tensile strength (harder) than the terminal material. Damage is a problem.

  Further, Patent Document 2 proposes that the serration groove depth is different, but the thickness of the crimp terminal used for the high-strength thin wire is as thin as 0.1 to 0.3 mm, and the groove depth is different. In addition, the high-strength thin wire is difficult to be deformed, so that it is difficult to enter the deep groove.

  For this reason, it is difficult to obtain a good electrical connection state by crimping a crimp terminal made of a normal terminal material to a high-strength thin wire with conventional techniques.

  An object of the present invention is to provide a high-strength thin wire crimping terminal capable of obtaining a good electrical connection state by crimping a high-strength thin wire with a crimping terminal made of a terminal material having a lower tensile strength. It is to provide.

  If the tensile strength of the narrow wire that crimps the crimp terminal is higher than the tensile strength of the crimp terminal material, the narrow wire is pressed against the serration during crimping, and the edge of the serration tends to collapse. The shear effect cannot be expected, and in this case, the elongation of the thin wire due to serration is the dominant mechanism of the oxide film breakage of the thin wire. Therefore, when the tensile strength of the narrow wire that crimps the crimp terminal is higher than the tensile strength of the crimp terminal material, it is important to make sure that the serrated wire is not collapsed during crimping and that the thin wire is easy to stretch. is there. Therefore, as a result of repeated experiments on the influence of the serration width and depth of the wire barrel portion and the angle of the side wall surfaces on the contact resistance of the crimping portion, the present invention has been completed.

  That is, the crimp terminal according to the present invention is a crimp terminal that crimps the wire barrel part to a high-strength thin wire having a tensile strength higher than the tensile strength of the crimp terminal material, and is formed on the inner surface of the wire barrel part. The serration width is not less than 0.8 times and not more than 1.3 times the diameter of the high-strength thin wire.

  According to experiments, the effect of reducing the contact resistance of the crimping part is high when the serration width is in the range of 0.8 times to 1.3 times the diameter of the high-strength thin wire. It turned out that the effect which reduces the contact resistance of a part becomes low. On the other hand, when the width is larger than 1.3 times, the number of serrations that can be formed in the wire barrel portion is not preferable.

  In the crimp terminal according to the present invention, the serration depth is preferably 40 to 60% of the diameter of the strand of the high-strength thin wire.

  According to the experiment, the serration depth is in the range of 40 to 60% of the diameter of the strand of the high-strength thin wire, and the effect of reducing the contact resistance of the crimping portion is high. It has been found that the effect of reducing the contact resistance of the crimping portion is reduced when the value exceeds.

  Moreover, it is preferable that the crimp terminal which concerns on this invention is the cross-sectional shape of a serration being an inverted trapezoid, and the inclination angle of the both-sides wall surface is 5-25 degrees.

  According to the experiment, the inclination angle of the both side walls of the serration is in the range of 5 to 25 °, and the effect of reducing the contact resistance of the crimping portion is high, and when it becomes smaller than 5 ° or exceeds 25 °, the contact of the crimping portion It has been found that the effect of reducing the resistance is reduced.

  According to the present invention, a good electrical connection state in which the contact resistance of the crimping portion is low can be obtained by crimping a crimp terminal made of a terminal material having a lower tensile strength to a high-strength thin wire.

Explanatory drawing which shows the relationship between the high intensity | strength thin diameter wire | line and serration width in this invention. The circuit diagram of the measuring device which measures the contact resistance of the crimping | compression-bonding part which crimped | bonded the crimp terminal to the high strength thin diameter wire. The graph which shows the relationship between the serration width at the time of crimping | bonding a crimp terminal to a high intensity | strength thin wire, and contact resistance. 4 is a graph created by adjusting the value of STEP 1 in FIG. 3 so as to overlap the value of STEP 2. Explanatory drawing which shows the relationship between the high intensity | strength thin diameter wire | line and serration depth in this invention. The graph which shows the relationship between the serration depth at the time of crimping | bonding a crimp terminal to a high intensity | strength thin wire, and contact resistance. Explanatory drawing which shows the relationship between the high intensity | strength thin wire | line in this invention, and the inclination angle of a serration both-sides wall surface. The graph which shows the relationship between the inclination angle of a serrated both-sides wall surface, and contact resistance at the time of crimping | bonding a crimp terminal to a high strength thin diameter wire. The perspective view which shows an example of the conventional crimp terminal.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As described above, in order to obtain a good electrical connection state by crimping a crimp terminal made of a terminal material having a lower tensile strength to a high-strength thin wire, the serration formed on the inner surface of the wire barrel portion is used. It is important to set the width, depth, and angle of both side walls appropriately.

Here, the high-strength thin wire has a wire diameter (diameter) d of 0.45 mm or less (cross-sectional area of 0.13 mm ² or less) and a tensile strength higher than the tensile strength of the material of the crimp terminal 1. Yes. Here, the tensile strength of the material of the crimp terminal 1 is a value obtained by measuring a JIS No. 5 shape sample in accordance with JISZ2201 in accordance with JISZ2201. The tensile strength of the high-strength thin wire 6 is also measured in accordance with JISZ2241.

<About serration width>
As shown in FIG. 1, the serration width is a distance a between the edge portions 6 of the serration 5 formed in the circumferential direction on the inner surface of the wire barrel portion 3 of the crimp terminal. If the serration width a is increased, the thin wire 7 is easily pushed into the serration during the pressure bonding, and the thin wire 7 is easily stretched. On the other hand, since the axial dimension of the wire barrel portion is limited, when the serration width is increased, the number of serrations is reduced and the number of places where the oxide film of the thin wire 7 is broken is reduced. Further, if the serration width is increased without reducing the number of serrations within the limited dimensions of the wire barrel portion, the serration interval s is reduced, and conversely, the peaks 8 between the serrations 5 are liable to be crushed. End up.

  Therefore, first, a serration width a suitable for a high-strength thin wire was examined. The high-strength thin wire used is a twisted wire having a diameter d = 0.31 mm obtained by twisting seven 0.11 mm Corson alloy strands, and has a tensile strength of about 1200 MPa.

 In addition, as a material of the high-strength thin wire, an alloy (for example, Cu-2.3) added with a trace element (Zn, Sn, Mg, etc.) based on a Cu-Ni-Si alloy (Corson alloy) in addition to a Corson alloy. Ni-0.55Si-0.15Sn-0.5Zn-0.1Mg alloy, Cu-3.75Ni-0.9Si-0.15Sn-0.5Zn-0.1Mg alloy), beryllium copper alloy (C1720W), or the like may be used.

On the other hand, prototypes of crimp terminals are as follows. In the experiment of STEP1, a plate of an alloy (Furukawa Electric Co., Ltd .: FAS680H) added with trace elements (Zn, Sn, Mg) based on a Corson alloy (Cu—Ni—Si alloy) as a terminal material is used. For crimp terminals with serration intervals s of 0.2 mm, 0.4 mm, 0.6 mm, 1 to 3 serrations, and serration depths w of 0.03 mm, 0.05 mm, and 0.07 mm, the serration width is 0. 1 mm, 0.2 mm, and 0.3 mm crimp terminals were prototyped. In the experiment of STEP2, as a terminal material, (1) C2600RH = brass (Furukawa Electric Co., Ltd., JIS H 3100 reference), (2)
C5210-8PEH = Phosphor bronze (Furukawa Electric Co., Ltd., JIS H 3130), (3) The same corson alloy (FAS680H) as STEP 1 is used, and the serration interval s is 0.3 mm, 0 Crimp terminals having serration widths of 0.2 mm, 0.3 mm, and 0.4 mm were prototyped for the crimp terminals with .35 mm, 0.4 mm, and three serrations, respectively. The tensile strength of each crimp terminal material is 600 to 700 MPa. Each of the prototype crimp terminals was crimped to a high-strength thin wire to obtain a measurement sample.

The contact resistance of the crimping part was measured for each sample. The contact resistance was measured with a measuring instrument shown in FIG. 2 (based on JIS K 7194). This measuring instrument determines the contact resistance of the crimping part as follows. First crimp terminals 1 by applying a current of 10mA to the measurement sample 9 was pressure bonded to a high strength thin line 7 (measured by ammeter A _1), and the crimping portion 10, the high strength thin wire length 100mm therefrom 7 The resistance R ₁ is obtained by measuring the voltage drop in the section including the voltmeter V ₁ . On the other hand, by applying a current to the high-strength thin lines 7S as a reference (measured by ammeter A _2), measured in the reference high strength thin lines 7S voltage drop length 100mm intervals with a voltmeter V ₂ determining the resistance _{R 2} by. Next, by calculating R ₁ -R ₂ , the resistance of the high-strength thin wire 7 having a length of 100 mm is excluded, and the contact resistance R of the crimping portion 10 is obtained. The test conditions are after a heat cycle of −40 ° C. × 15 minutes ← → 120 ° C. × 15 minutes.

  The measurement results are shown in FIG. According to FIG. 3, it can be seen that both STEP1 and STEP2 start to decrease in contact resistance when the serration width exceeds 0.2 mm. Since the contact resistance decreasing tendency from the serration width 0.2 mm to 0.3 mm is the same for both STEP 1 and STEP 2, the value of the serration width 0.2 mm is the same as the value of the serration width 0.2 mm of STEP 1. If a constant coefficient is multiplied so that the graph of STEP1 is superimposed on the graph of STEP1, the result is as shown in FIG. According to FIG. 4, it can be seen that when the serration width is 0.25 mm (0.8 times the wire diameter 0.31 mm), the effect of reducing the contact resistance appears surely. Further, as the serration width is increased to 0.3 mm (1 times the wire diameter) and 0.4 mm (1.3 times the wire diameter), the effect of reducing the contact resistance becomes more prominent. Therefore, the serration width is preferably 0.8 times or more of the wire diameter, more preferably 1 time or more.

  On the other hand, since the serration width is limited by the size of the wire barrel part, if the serration width is wider than 1.3 times the wire diameter, the number of serrations must be reduced, and the oxide film of the high-strength thin wire effectively Can no longer be destroyed. Further, if the number of serrations is not reduced, the serration interval s becomes narrow, and the peak portions 8 between the serrations 5 are crushed during crimping. For this reason, the serration width is preferably 1.3 mm or less.

In the experiment, a high-strength thin wire having a diameter of 0.31 mm was used, but the diameter d of the thin wire and the serration width a are in a proportional relationship as will be described below. The same can be considered. In other words, the cross-sectional secondary moment I of the cross section circle, when the diameter is d, the I = πd ^4/64. The maximum deflection amount v of a beam having a uniform distribution weight (pressure) p in the longitudinal direction applied to a beam having a circular cross section supported at two points is represented by v = 5 pa ^{4 where} E is the Young's modulus of the beam. / 384EI = 5pa ⁴ / 6Eπd ⁴ (from the mechanical engineering manual). Here, if the maximum deflection amount v is larger than the serration depth w, the contact resistance can be reduced. Therefore, a ≧ (6Eπw / 5p) ^1/4 d = kd [where k = (6Eπw / 5p) ^1/4 ]. Therefore, the conductor diameter d and the serration width a are in a proportional relationship.

<About serration depth>
Next, the serration depth suitable for high-strength thin wires was examined. The serration depth is a distance w from the inner surface of the wire barrel portion 3 to the bottom surface of the serration 5 as shown in FIG. If the serration depth w is too shallow, the high-strength thin wire 7 does not enter the serration 5, and if it is too deep, the edge portion 6 of the serration 5 may be broken by the pressure-bonding force. For serrated terminals with serration intervals s of 0.2, 0.4 mm, 0.6 mm, 1 to 3 serrations, and serration widths a of 0.1 mm, 0.2 mm, and 0.3 mm, the serration depth w is Crimp terminals of 0.03 mm, 0.05 mm, and 0.07 mm were manufactured as prototypes (the terminal material is the same as in STEP 1).

  These crimp terminals were crimped to high-strength thin wires (same as in the case of serration width) to obtain measurement samples, and the contact resistance of the crimp portion was measured for each sample. The result is shown in FIG. According to FIG. 6, the serration depth is about 0.04 mm to 0.06 mm (the contact resistance is reduced in the range of about 40 to 60% of the diameter ds = 0.11 mm of the strand 7a of the high strength thin wire 7). It can be seen that the contact resistance is lowest when the thickness is 0.05 mm (50% of the strand diameter ds). Therefore, the serration depth is preferably 40 to 60% of the strand diameter ds of the high-strength thin wire, and more preferably 50% of the strand diameter ds of the high-strength thin wire.

<Inclination angle on both side walls of serration>
Next, the inclination angle of both side walls of serration suitable for high-strength thin wire was examined. As shown in FIG. 7, the inclination angle of the both side wall surfaces of the serration is an inclination angle θ with respect to a plane perpendicular to the axial direction of the wire barrel portion 3 of the both side wall surfaces 11 of the serration 5 having an inverted trapezoidal cross section. It is considered that the edge portion 6 of the serration 5 is more likely to be broken during pressure bonding as the inclination angle θ of the side wall surfaces 11 is smaller. Therefore, for the crimp terminals with serration intervals s of 0.2, 0.4 mm, 0.6 mm, 1 to 3 serrations, and serration widths a of 0.1 mm, 0.2 mm, and 0.3 mm, respectively, Crimp terminals with wall surface 11 having an inclination angle θ of 1 °, 15 °, and 30 ° were fabricated (terminal materials are the same as in STEP 1).

  These crimp terminals were crimped to a high-strength thin wire 7 (same as in the case of serration width) to obtain measurement samples, and the contact resistance of the crimp portion was measured for each sample. The result is shown in FIG. According to FIG. 8, it can be seen that the effect of reducing the contact resistance appears in the range of 5 to 25 ° of the inclination angle of the both side walls of the serration, and the contact resistance becomes the lowest when the angle is 15 °. Therefore, the inclination angle of both side wall surfaces of the serration is preferably 5 to 25 °, and more preferably 15 °.

1: Crimp terminal 2: Contact portion 3: Wire barrel portion 4: Insulation barrel portion 5: Serration 6: Edge portion 7: High-strength thin wire 8: Peak portion 9: Measurement sample 10: Crimp portion 11: Side wall surface d : Diameter of high-strength thin wire ds: Diameter of strand of high-strength thin wire a: Serration width s: Serration interval w: Serration depth θ: Angle of inclination of side wall surface

Claims (3)

  A crimp terminal for crimping the wire barrel portion to a high-strength thin wire having a tensile strength higher than the tensile strength of the crimp terminal material, wherein the serration width formed on the inner surface of the wire barrel portion is the high-strength thin wire A crimp terminal for a high-strength thin wire having a diameter of 0.8 to 1.3 times the diameter of the wire.   The crimp terminal for high-strength thin wire according to claim 1, wherein the depth of the serration is 40 to 60% of the diameter of the strand of the high-strength thin wire.   The crimp terminal for high-strength thin wire according to claim 1 or 2, wherein the cross-sectional shape of the serration is an inverted trapezoid, and the inclination angle of both side wall surfaces is 5 to 25 °.

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