JP5017156B2 - Crimping method of terminal to electric wire - Google Patents

Description

  The present invention relates to a crimping method effective particularly when crimping a terminal to an aluminum electric wire.

  Conventionally, the electric wire used for the wire harness for automobiles is generally a copper electric wire, but recently, there is a movement to replace it with an aluminum electric wire because of its light weight and good recyclability.

  This is because aluminum has a conductivity of about 60% as compared with copper, but the weight only needs to be 1/3, so that significant weight reduction can be expected. Further, the melting point of copper is 1083 ° C., whereas the melting point of aluminum is 660 ° C., so that there is an advantage that the metal can be easily recovered.

  When the wire of an automobile wire harness is made of an aluminum wire, there is a problem in connecting terminals that there is a strong oxide film with high electrical resistance, especially on the surface of the conductor made of aluminum or aluminum alloy. May be.

  FIG. 4 shows a general example in the case where the aluminum electric wire 21 and the aluminum terminal 30 described in Patent Document 1 are connected by crimping. The terminal 30 has a connection plate part 31 with a hole 31a at the front part and a crimping part 32 at the rear part. The crimping portion 32 has a U-shape having a bottom plate 33 and a pair of crimping pieces 34, 34 extending upward from both lateral edges of the bottom plate 33, and has a serration 35 on the inner surface. The aluminum electric wire 21 is obtained by covering the outer periphery of a conductor portion 22 made of stranded wire or the like with an insulating coating 23. When crimping the terminal 30, the exposed conductor 22 at the end of the peeled electric wire 21 is placed on the bottom plate 33. The crimping pieces 34 on both sides are bent inward by a crimping device and crimped so as to wrap the conductor portion 32. Thereby, the terminal 30 can be crimped to the conductor portion 22.

  Thus, conventionally, by forming serrations 35 on the inner surface of the crimping part 32, the oxide film on the surface of the conductor part 22 is destroyed during crimping. Further, in order to further increase the effect of destroying the oxide film on the surface of the conductor portion 22, it is proposed in Patent Document 1 to form the serration 35 obliquely.

In addition, as a method of crimping a terminal while destroying an oxide film on the surface of the conductor portion, Patent Document 2 discloses that the conductor portion is provided with ultrasonic vibration in a state where the crimp portion of the terminal is set on the conductor portion of the electric wire. A method has been proposed in which the crimping portion of the terminal is crimped to the conductor portion by caulking while the terminal is metal-joined.
JP 2003-249284 A JP 2003-86259 A

  By the way, since the technique of patent document 1 removes the oxide film on the surface of a conductor part by the sliding at the time of a conductor part extending, contacting the board surface of a terminal which has a serration, the conductor of an electric wire The problem of the oxide film existing between the contact surfaces of the strands constituting the part could not be solved. In other words, an oxide film is also present on the contact surface between the wires constituting the conductor part, but particularly in the case of thick wires, the oxide film between the wires becomes an obstacle and the terminal is crimped. There was a problem that the connection resistance was not reduced. When the resistance between the strands is large, in the case of a thick wire (for example, 30 sq or more) that carries a large current, the resistance between the strands raises the temperature of the terminal connection, and in the worst case, it is called erosion. There is also a risk of a situation. In particular, in the case of an aluminum electric wire, there is a problem that the heat conductivity is poor because aluminum has a lower thermal conductivity than copper, and the resistance between the wires cannot be ignored.

  In this regard, according to the technique described in Patent Document 2, since the strands can be metal-bonded by applying ultrasonic vibration, the problem of resistance between the strands can be eliminated.

  However, since ultrasonic vibration is applied simultaneously with pressure bonding, the energy required to cause effective vibration between the wires becomes very large, making it impossible to apply to thick wires. .

  In consideration of the above circumstances, the present invention effectively reduces the resistance between the strands constituting the conductor portion of the electric wire by applying ultrasonic vibration with a small energy even when applied to a thick electric wire. It aims at providing the crimping method which can be performed.

  The method for crimping a terminal to an electric wire according to the invention of claim 1 is a method for crimping a terminal against an electric wire, wherein the crimping portion of the terminal is crimped so as to be wrapped from the outside with respect to the conductor portion of the electric wire formed of a bundle of many strands. The conductor portion of the electric wire is set in an ultrasonic bonding machine as a single unit, and ultrasonic vibration is applied to the conductor portion by the ultrasonic bonding machine, so that the wire constituting the conductor portion and the wire After performing the preliminary step of causing the sliding between the contact surfaces to roughen the surface of the wire, performing this step of pressing the crimp portion of the terminal to the outer periphery of the conductor portion by pressurization. Features.

  Invention of Claim 2 is the crimping method of the terminal with respect to the electric wire of Claim 1, Comprising: In the said preliminary | backup process, between the contact surface of the strand which roughened the surface and the strand is preliminarily joined It is characterized by applying ultrasonic vibration.

  A third aspect of the invention is a method for crimping a terminal against an electric wire according to the first or second aspect, wherein the strand is a non-plated strand made of aluminum or an aluminum alloy.

  According to the first aspect of the present invention, the preliminary step of roughening the contact surfaces of the strands by applying ultrasonic vibration and the main step of pressing the terminal to the conductor portion of the electric wire by pressurization are performed separately. In the process, the effective sliding required for roughening the surface can be caused between the strands only by applying a small energy ultrasonic vibration. That is, when ultrasonic vibration is simultaneously applied in the process of press-bonding the terminal as in the conventional case, a large amount of ultrasonic energy is required because sliding is performed in a state in which the terminal is restrained. However, in the present invention, the sliding between the strands is caused not at the time of crimping the terminals but before the joining of the terminals, that is, in a free state where there is no constraint on the strands. Even in the case of a thick electric wire, it is possible to cause the surface of the wire to be rough by sliding between the wires by ultrasonic vibration with small energy. Therefore, by pressing and pressing in this step with the surface roughened, the adhesion between the terminal and the conductor part of the wire and the adhesion between the strand and the strand while breaking the oxide film Can increase the sex. As a result, it is possible to reduce the resistance of the connection portion, thereby avoiding an increase in temperature when a large current flows. This can be said to be particularly useful in the case of aluminum, which has a lower thermal conductivity than copper. Moreover, since it is only necessary to apply ultrasonic vibration with a small energy, the manufacturing burden can be reduced.

  According to the second aspect of the present invention, the contact surface between the strands whose surfaces are roughened and the strands are preliminarily joined in the preliminary process stage, so that the contact resistance between the strands can be further reduced. .

  According to the invention of claim 3, the effectiveness can be exhibited particularly when the aluminum electric wire and the terminal are crimped. That is, in the case of an aluminum electric wire, a strong oxide film exists on the surface of the aluminum or aluminum alloy wire, which is an obstacle to reducing the connection resistance. Since crimping is performed in a rough state, the terminal and the aluminum electric wire can be connected with a small electric connection resistance while eliminating the influence of the oxide film.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1A to 1C are process explanatory views of the crimping method according to the embodiment, FIG. 2 is a principle explanatory view of a preliminary process, and FIG. 2A is a conductor portion of an electric wire when ultrasonic vibration is applied. 2B is a diagram seen from the same side, FIG. 3 is a schematic diagram for explaining the effect of this process, and FIG. 3A is a diagram showing that the surface is not particularly roughened. Figure (left figure) during crimping operation when done, figure after right crimping (right figure), and Fig. 3 (b) are figures during crimping work after roughing the surface (left figure) ) And the figure after crimping (right figure).

  The crimping method of this embodiment is a method in the case of crimping a copper or aluminum aluminum wire crimp terminal (terminal) to an aluminum wire for a wire harness used in an automobile. As shown to Fig.1 (a), the aluminum electric wire 1 covers the outer periphery of the conductor part 2 comprised by twisting the non-plating strand 2 made from aluminum or aluminum alloy, and covered the insulation coating 4. As shown in FIG.

  In this crimping method, in the first step, as shown in FIG. 1A, the insulating coating 4 at the end of the electric wire 1 is peeled off to expose the conductor 2 by a required length.

  Next, in a preliminary process, as shown in FIG. 2, the conductor portion 2 of the electric wire 1 is set as it is between the horn 8 and the anvil 9 of the ultrasonic bonding machine 7, and the ultrasonic bonding machine 7 conducts the conductor. By applying ultrasonic vibration to the part 2, sliding (adhesion) is caused between the contact surfaces of the strand 3 and the strand 3 constituting the conductor portion 2, thereby roughening the surface of the strand 3. To do.

  At this time, the direction of the ultrasonic vibration may be set to a direction orthogonal to the longitudinal direction of the conductor portion 2 as indicated by an arrow A in FIG. 2A, or an arrow in FIG. As indicated by B, it may be set in the direction along the longitudinal direction of the conductor portion 2 or may be set in both directions.

  Next, after performing the preliminary step described above, the present step of crimping the crimping portion 12 of the terminal 10 as the crimping terminal for the aluminum wire to the outer periphery of the conductor portion 2 by pressurization is performed, whereby FIG. A finished product after crimping as shown in FIG. This terminal 10 has a connecting plate part 11 with a hole 11a in the front part and a crimping part 12 in the rear part. The crimping part 12 includes a bottom plate 13 continuous from the connecting plate part 11, and the width of the bottom plate 13. It has a U-shape with a pair of crimping pieces 14 and 14 extending upward from both side edges in the direction.

  In this step, the preliminarily joined conductor portion 2 shown in FIG. 1B is placed on the bottom plate 13 of the crimping portion 12 of the terminal 10, and in this state, both crimping pieces 14 are rolled inward to form the B type. Crimping is completed by crimping.

  FIG. 3 is a schematic diagram showing a difference in bonding state between the strands by crimping, and FIG. 3A is a state during the crimping operation in the comparative example in which the crimping is performed without particularly roughening the surface (left). FIG. 3B is a view showing the state (right) after crimping, and FIG. 3B is a state during the crimping operation (left) and the state after crimping (right) in this embodiment in which the surface is roughened and crimped. ).

  As shown in FIG. 3 (a), when pressure bonding is performed in this step without particularly roughening the contact surface S, the adhesion between the strands 3 and 3 cannot be progressed much, The area of the adhesion surface G becomes small. On the other hand, as shown in FIG. 3 (b), when pressure bonding is performed in this step with the contact surface S roughened, the wire 3 and the element wire 3 are broken while breaking the oxide film present on the surface. The line 3 can be adhered, the area of the adhesion surface G can be increased, and the contact resistance can be reduced.

  As described above, in the crimping method of the present embodiment, the preliminary process of roughening the contact surfaces of the strands 3 by applying ultrasonic vibration and the book for crimping the terminal 10 to the conductor portion 2 of the electric wire 1 by pressing. Since the process is performed separately, effective sliding necessary for roughening the surface can be caused between the strands 3 only by applying a small energy ultrasonic vibration in the preliminary process. .

  That is, when ultrasonic vibration is simultaneously applied in the process of press-bonding the terminal as in the conventional case, a large amount of ultrasonic energy is required because sliding is performed in a state in which the terminal is restrained. However, in the present embodiment, not between the time when the terminals 10 are crimped but before the terminals 10 are joined, that is, in a free state where there is no restriction on the wires 3, between the wires 3. Since the sliding is caused, even in the case of a thick (large diameter) electric wire, the surface of the strand 3 is roughened by sliding between the strands 3 by ultrasonic vibration with a small energy. Is possible.

  Therefore, by pressing and pressing in this step with the surface roughened, the adhesion between the terminal 10 and the conductor portion 2 of the electric wire 1 and the strands 3 and 3 are broken while breaking the oxide film. As a result, the resistance of the terminal connection portion can be reduced, thereby avoiding an increase in temperature when a large current flows.

  This is particularly useful in the case of an aluminum wire that has a lower heat dissipation than a copper wire. Moreover, since it is only necessary to apply ultrasonic vibration with a small energy, the manufacturing burden can be reduced.

  In addition, in the above-described preliminary process, by further applying ultrasonic vibration between the contact surfaces of the strand 3 and the strand 3 whose surfaces are roughened, the contact surface of the strand 3 and the strand 3 is melted, The wires 3 may be preliminarily joined. By doing so, the contact resistance between the strands 3 can be further reduced.

(A)-(c) is process explanatory drawing of the crimping | compression-bonding method of embodiment of this invention. It is a principle explanatory view of a preliminary process in the method, (a) is a view of the conductor portion of the wire when applying ultrasonic vibration from the front, (b) is a view from the side. FIG. 4 is a schematic diagram showing a difference in bonding state between strands by crimping, in which (a) shows a state during the crimping operation (left) and a state after crimping (in the case of the comparative example in which the crimping is performed without particularly roughening the surface ( (B) is a diagram showing a state during the crimping operation (left) and a state after the crimping (right) in the present embodiment in which the crimping is performed after the surface is roughened. It is explanatory drawing of the crimping method of a general terminal.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric wire 2 Conductor part 3 Elementary wire 7 Ultrasonic bonding machine 10 Crimp terminal (terminal) for aluminum electric wires
12 Crimp part 14 Crimp piece

Claims (3)

1. In the crimping method of the terminal against the electric wire to be crimped so that the crimping portion of the terminal is wrapped from the outside with respect to the conductor portion of the electric wire consisting of a bundle of many strands,
   The conductor part of the electric wire is set in an ultrasonic bonding machine as a single unit, and the ultrasonic wave is applied to the conductor part by the ultrasonic bonding machine, so that the wire constituting the conductor part is in contact with the wire. After performing a preliminary step of causing the sliding between the surfaces to roughen the surface of the wire, this step of pressing the crimping portion of the terminal on the outer periphery of the conductor portion by pressing is performed. Crimping method of the terminal to the wire.
2. A method for crimping a terminal to an electric wire according to claim 1,
   A method for crimping a terminal against an electric wire, wherein ultrasonic vibration is applied until a contact between the surface of the wire whose surface is roughened and the contact surface of the wire is preliminarily joined in the preliminary step.
3. A method for crimping a terminal against an electric wire according to claim 1 or 2,
   A method for crimping a terminal against an electric wire, wherein the element wire is a non-plated element wire made of aluminum or an aluminum alloy.

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