JP2009248172A - Connection method of coated electrical wire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a connection method of a coated electrical wire by which superior connection reliability can be secured at low cost, even if the melting temperature of an oxide film formed on the surface of an electrical wire is sufficiently higher than that of a conductive member. <P>SOLUTION: This is a connection method of a coated electrical wire, in which a coated electrical wire coated with an insulated film is connected to a conductive member having melting temperature lower than that of the oxide film formed on the surface of the electrical wire. The conductive member is pressurized so as to come in contact with a part of the insulated film, with an electric current made to flow in the conductive member to generate heat. As a result, a part of the insulated film and of the oxide film are removed, tack-welding a contact face of the stripped electrical wire and conductive member. irradiating the tack-welded contact face with a laser beam, melting/welding the electrical wire and the conductive member at the contact face. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for connecting a covered electric wire and a conductive member.

  For example, Patent Documents 1 and 2 disclose a method of connecting a covered electric wire and a conductive member.

  The connection method disclosed in Patent Document 1 is a connection method called resistance welding, and is a method of energizing a conductive member and an insulated coated electric wire covered with an insulating coating while applying pressure. In Patent Document 1, a conductive member having a substantially U-shaped cross section is formed by connecting a base and a folded portion facing the base by a bent portion, and an insulation-coated electric wire is sandwiched between the base and the folded portion. The base portion and the folded portion are pressurized by a pair of electrodes. In this pressurized state, a current is passed through the conductive member by the pair of electrodes, thereby causing the conductive member to generate heat, and this heat is transmitted to the insulating coating of the insulated coated electric wire held between the conductive members. Then, the insulating coating softened by the heat and the applied pressure is caused to flow from the contact portion with the conductive member, and the conductive member and the bare electric wire are connected.

Further, the connection method disclosed in Patent Document 2 is a connection method called laser welding, in which a conductive member and an insulation-coated electric wire are fixed while fixing a conductive member and an insulation-coated electric wire covered with an insulation film. This is a method of irradiating the contact surface with laser light. In Patent Document 2, a conductive wire (electric wire) covered with an insulating coating is fixed on a conductive member by a guide portion (jig) provided on a metal terminal (conductive member), and the insulation-coated electric wire is irradiated with laser light. As a result, the insulation coating of the insulation-coated electric wire is removed. Then, the electric wire and the conductive member that have been exposed after the insulating coating is removed are brought into contact with each other, and the contact surface between the electric wire and the conductive member is irradiated with laser light so as to connect the electric wire and the conductive member. I have to.
Japanese Patent Application Laid-Open No. 11-114674 Japanese Patent Laid-Open No. 9-122951

By the way, in the connection method shown by patent document 1, welding may become impossible depending on the combination of an electric wire and a conductive member. Usually, a copper alloy (brass) is adopted as a constituent material of the conductive member, and copper or aluminum is adopted as a constituent material of the electric wire. Since aluminum is cheaper and lighter than copper, the cost can be reduced and the weight of the electric wire can be reduced. However, aluminum is easily combined with oxygen in the air, and forms an insulating oxide film (alumina Al ₂ O ₃ ) on the surface of the electric wire. The melting point temperature of alumina is sufficiently higher than the melting point temperature of brass, and in the method (resistance welding) disclosed in Patent Document 1, only the conductive member having a low melting point temperature is melted, and the conductive member and the electric wire are not connected.

  On the other hand, in the connection method shown in Patent Document 2, laser light is applied locally even when the melting point temperature of the oxide film formed on the surface of the electric wire is sufficiently higher than the melting point temperature of the conductive member. Can be welded. However, in the method (laser welding) disclosed in Patent Document 2, if there is a gap in the welded portion between the electric wire and the conductive member, a strong joint cannot be obtained. It is necessary to irradiate the contact surface with the conductive member with a laser. For this reason, the shape of the jig for pressurization becomes complicated, which causes an increase in cost. Further, when the insulation-coated electric wire is irradiated with laser light from one direction, the opposite surface may become a shadow, and the coating may remain on the opposite surface. Therefore, a film remains between the electric wire and the conductive member, the contact state between the electric wire and the conductive member becomes unstable, and the connection reliability between the electric wire and the conductive member may be reduced. In addition, although the method of irradiating a covered electric wire from multiple directions is also considered, in this method, the mechanism which irradiates a laser beam from many directions becomes complicated and causes a cost increase.

  Therefore, in view of the above problems, the present invention ensures good connection reliability at low cost even when the melting point temperature of the oxide film formed on the surface of the electric wire is sufficiently higher than the melting point temperature of the conductive member. It aims at providing the connection method of the covered electric wire which can do.

  In order to achieve the above-described object, the invention according to claim 1 is directed to a coated electric wire in which an electric wire is covered with an insulating film, and a conductive material having a melting point temperature lower than a melting point temperature of an oxide film formed on the surface of the electric wire. A method for connecting a covered electric wire for connecting a member, wherein the conductive member is pressurized so as to be in contact with a part of the insulating coating, and a portion of the insulating coating that is in contact with the conductive member is heated by flowing a current through the conductive member. A conductive member in the oxide film by applying an electric current to the conductive member to generate heat by pressurizing the conductive member in contact with the exposed oxide film from which the insulating film has been removed. A temporary joining step of temporarily joining the contact surface between the electric wire and the conductive member, which has been exposed after the oxide film is removed, and the temporary contacted contact surface. By irradiating laser light, which characterized by comprising a laser welding step of fusion bonding the wire and the conductive member in the abutment surface.

  The temporary bonding step is a step of removing the portion of the oxide film that comes into contact with the conductive member, and temporarily bonding the exposed wire and the conductive member from which the oxide film has been removed, so that it is welded to a sufficient bonding strength. It is not necessary to have such a joining strength as long as the electric wire and the conductive member are not peeled off in the subsequent laser welding process. For this reason, even if it is the combination of the material of an electric wire and a conductive member that melting | fusing point temperature of the oxide film formed on the surface of an electric wire is sufficiently higher than melting | fusing point temperature of a conductive member, it can employ | adopt.

  By performing the temporary joining, a jig for fixing the electric wire and the conductive member, which has been conventionally required at the time of laser irradiation, in the subsequent laser welding process becomes unnecessary, and the cost can be reduced. In addition, as described above, the electric wire and the conductive member are temporarily joined. As a result, the gap between the electric wire and the conductive member is almost zero, so that the contact between the electric wire and the conductive member is stable. A laser beam can be applied to the contact surface between the conductive member and the conductive member. Thereby, the favorable connection state of an electric wire and a conductive member can be obtained.

  As described above, the method for connecting the above-mentioned covered electric wire is connectable even when the melting point temperature of the oxide film formed on the surface of the electric wire is sufficiently higher than the melting point temperature of the conductive member, and is good at low cost. It is a method of connecting a covered electric wire that can ensure reliable connection reliability.

  In the invention described in claim 1, as described in claim 2, aluminum is suitable as the material of the electric wire. Thereby, compared with the case where copper is employ | adopted as a constituent material of an electric wire, cost reduction and the weight reduction of an electric wire can be achieved.

  In the invention according to claim 1 or 2, as described in claim 3, the conductive member is formed by connecting the base portion and the folded portion facing the base portion by a bent portion, and the base portion and the folded portion. The conductive member may be in contact with a part of the insulating coating by pressurizing the base portion and the folded portion with the covered electric wire sandwiched therebetween.

  According to this, since the conductive member has the bent portion, the current concentrates on the bent portion and locally generates heat. Thereby, heat can be efficiently transferred to the insulating coating in contact with the conductive member. Further, since the covered electric wire can be sandwiched between the base portion and the folded portion, laser welding can be performed in a state in which the contact state between the covered electric wire and the conductive member is favorably maintained.

  In the invention according to any one of claims 1 to 3, as described in claim 4, the conductive member and the covered electric wire may be pressurized by a pair of electrodes for passing a current through the conductive member. According to this, while pressing a conductive member and a covered electric wire with the electrode which makes a pair, an electric current can be sent through a conductive member. Therefore, the apparatus configuration for connecting the conductive member and the covered electric wire can be simplified.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a perspective view showing a connection structure of a covered electric wire obtained by the connection method according to the first embodiment. 2 is a cross-sectional view taken along line II-II in FIG.

  As shown in FIG. 1 and FIG. 2, the covered electric wire 10 is formed by covering the periphery of an electric wire 11 having a circular cross section (hereinafter, referred to as a round electric wire 11) with an insulating coating 12. Connected and integrated.

  The round electric wire 11 is made of a valve metal (valve metal) having an oxide film formed on the surface, and in this embodiment, aluminum is adopted as a constituent material of the round electric wire 11. Aluminum has a property of forming alumina having a melting point temperature of 2020 ° C. in combination with oxygen in the air, and an oxide film 13 (alumina) is formed on the surface layer of the round electric wire 11. Moreover, the circumference | surroundings of the round shape electric wire 11 (oxide film 13) are coat | covered with the insulating film 12 which consists of synthetic resins, such as a polyamideimide, for example. Then, as shown in FIG. 2, a part of the insulating coating 12 and the oxide coating 13 facing the conductive member 20 in the covered electric wire 10 is removed, and a part of the round electric wire 11 is directly connected to the conductive member 20. (Joined).

  The conductive member 20 is a terminal for electrically connecting the covered electric wire 10 and another member, and a part of the electric wire 20 is exposed by removing the insulating coating 12 and the oxide coating 13, and the round electric wire 11 is exposed. Are directly connected (joined). The conductive member 20 is made of a material having a melting point temperature lower than the melting point temperature of the oxide film 13. In this embodiment, brass having a melting point temperature of 905 ° C. is adopted as a constituent material of the conductive member 20. As shown in FIGS. 1 and 2, as the conductive member 20, a conductive member having a substantially U-shaped cross section in which a base portion 21 and a folded portion 22 facing the base portion 21 are connected by a bent portion 23 is employed. is doing. The covered electric wire 10 is arranged in the vicinity of the bent portion 23 with respect to the conductive member 20 having a substantially U-shaped cross section. And the covered electric wire 10 is clamped by the base 21 and the folding | returning part 22, and the round shaped electric wire 11 is connected (joined) with the base 21 and the folding | turning part 22 in this clamping site | part.

  Next, the connection method of the covered electric wire 10 which is the characteristic part of this embodiment is demonstrated based on FIGS. FIG. 3 is a cross-sectional view showing a preparation step in the connection step between the covered electric wire 10 and the conductive member 20. FIG. 4 is a cross-sectional view showing the insulating film removing step. FIG. 5 is a cross-sectional view showing a temporary joining step. FIG. 6 is a cross-sectional view showing a laser welding process.

  When connecting the covered electric wire 10 to the conductive member 20, first, as shown in FIG. 3, the conductive member 20 having a substantially U-shaped cross section is formed on one electrode 30 of the pair of electrodes 30, 31. The outer surface is arranged as a contact surface. The electrode 30, together with the electrode 31, not only allows a current to flow to the conductive member 20, but also serves as a support base for the conductive member 20. And the covered electric wire 10 is arrange | positioned on the inner surface (opposite surface with the folding | turning part 22) of the base 21. FIG. The above is the preparation process.

  After completion of the preparation process, pressurization is performed. In this pressurization, as shown in FIG. 4, the electrode 31 is brought into contact with the outer surface side of the folded portion 22, and a force is applied to the folded portion 22 by the electrode 31 toward the electrode 30 (white arrow in FIG. 4). Add As a result, the folded portion 22 approaches (displaces) the base portion 21 and the covered electric wire 10 is sandwiched between the base portion 21 and the folded portion 22. And electricity supply is implemented in the pressurized state. In this energization, a voltage is applied between the pair of electrodes 30 and 31 while maintaining a pressurized state, and a current is passed between the electrodes 30 and 31 via the conductive member 20. Thereby, the conductive member 20 generates heat. In the present embodiment, as shown in FIG. 4, an electric current (see a solid line arrow in FIG. 4) flows from the electrode 31 to the electrode 30 through the folded portion 22, the bent portion 23, and the base portion 21 of the conductive member 20. It has become. Therefore, since the current path between the base portion 21 and the folded portion 22 is only the bent portion 23, the bent portion 23 where current is concentrated can be locally heated. Thereby, heat is transmitted from the conductive member 20 to the covered electric wire 10, and the temperatures of the insulating coating 12 and the oxide coating 13 rise.

  Then, as shown in FIG. 4, the insulating coating 12 softened by the heat generated by the pressurization and energization is caused to flow from the contact portion with the conductive member 20, and a part of the oxide coating 13 is exposed. The process up to this point corresponds to the insulating film removing step described in the claims.

  Next, as shown in FIG. 5, the exposed oxide film 13 and the conductive member 20 are brought into contact with each other, and the oxide film 13 is softened by the above-described pressurization and energization. Then, the oxide film 13 that is in contact with the conductive member 20 is pushed out from the contact portion with the conductive member 20, and a part of the round electric wire 11 that is exposed is brought into contact with the conductive member 20. Thereby, the contact surface of the round electric wire 11 and the conductive member 20 (at least one of the contact surface of the round electric wire 11 and the folded portion 22 and the contact surface of the round electric wire 11 and the base portion 21) is formed. Temporarily joined by resistance welding. The process up to this point corresponds to the temporary joining step described in the claims. As described above, it is not necessary to join the round electric wire 11 and the conductive member 20 to a sufficient bonding strength, and the bonding strength is such that the round electric wire 11 and the conductive member 20 are not peeled off in a laser welding process described later. I just need it.

  Next, as shown in FIG. 6, the contact surface (the part temporarily joined between the round electric wire 11 and the folded portion 22, and the round electric wire 11, which are temporarily joined with the round electric wire 11 and the conductive member 20). The circular electric wire 11 and the conductive member 20 are melt-bonded by irradiating laser light (see the white arrow in FIG. 6) to the base 21 via at least one of the temporarily bonded portions). . This laser welding process ensures the necessary welding strength between the conductive member 20 and the round electric wire 11. In laser welding, by scanning a laser beam within a predetermined range, it is possible to widen a formation region of a part melted by the laser beam and to secure necessary welding strength. This ensures good connection reliability. Up to this point corresponds to the laser welding process described in the claims. In this embodiment, a YAG laser is used as the laser light.

  Next, the effect of the connection method of the covered wire 10 according to the present embodiment will be described. As described above, in this embodiment, the contact surface between the round electric wire 11 and the conductive member 20 is temporarily joined, and then the contact surface between the round electric wire 11 and the conductive member 20 is laser-welded. Therefore, a jig for fixing the covered electric wire 10 and the conductive member 20 that has been conventionally required at the time of laser irradiation becomes unnecessary, and the cost can be reduced.

  In addition, the round electric wire 11 and the conductive member 20 are temporarily joined, and the round electric wire 11 and the conductive member 20 are integrated at the temporarily joined portion, so that the gap between them becomes almost zero. Therefore, the contact surface between the round electric wire 11 and the conductive member 20 can be irradiated with laser light while the contact between the round electric wire 11 and the conductive member 20 is stable. Thereby, the favorable connection state of the round electric wire 11 and the conductive member 20 can be obtained.

  Insulating coating 12 is obtained by irradiating coated electric wire 10 with laser light in a state in which coated electric wire 10 is caulked inside conductive member 20 having a substantially U-shaped cross section (between base portion 21 and folded portion 22). A method of removing the oxide film 13 and connecting the round electric wire 11 and the conductive member 20 is also conceivable. However, in this method, the insulating coating 12 and the oxide coating 13 are removed by laser light irradiation, and the conductive member 20 and the round electric wire 11 are melt-bonded. Therefore, the vaporized insulating coating 12, the molten oxide coating 13, The molten conductive member 20 and the molten round electric wire 11 are mixed in the vicinity of the joint between the conductive member 20 and the round electric wire 11. As a result, the insulating coating 12 vaporized by the laser beam is mixed into the welded portion between the conductive member 20 and the round electric wire 11 to form a gap at the joint, and the connection reliability between the conductive member 20 and the round electric wire 11 is improved. May decrease. In addition, since the insulating coating 12 and the oxide coating 13 are removed in a state where the covered electric wire 10 is crimped by the conductive member 20, the contact state between the round electric wire 11 and the conductive member 20 that are in a bare state is not ensured, which is favorable. It becomes difficult to ensure a contact state. Further, as described above, since the covered electric wire 10 is caulked by the conductive member 20, residual stress is generated in the conductive member 20, and there is a possibility that the connection reliability is also lowered.

  On the other hand, in the connection method shown in the present embodiment, a part of the insulating coating 12 and the oxide coating 13 softened by the heat generated by energization is removed by pressurization, and the round electric wire 11 and the conductive member that are exposed. Laser welding is performed after the contact surface with 20 is temporarily joined. That is, the round electric wire 11 and the conductive member 20 are melt-bonded in a state where the insulating coating 12 (and the oxide coating 13) is not interposed between the round electric wire 11 and the conductive member 20. Therefore, connection reliability can be improved compared to the connection method described above. Further, as described above, since the round electric wire 11 and the conductive member 20 are temporarily joined, a good contact state between the round electric wire 11 and the conductive member 20 can be ensured. Moreover, since the conductive member 20 is generating heat, the residual stress of the conductive member 20 caused by pressurization can be relaxed by heat.

  In the present embodiment, aluminum is adopted as a constituent material of the round electric wire 11. Therefore, compared with the case where copper is adopted as the constituent material of the round electric wire 11, the cost can be reduced and the electric wire can be reduced in weight.

  In the present embodiment, the conductive member 20 has a substantially U-shaped cross section. Therefore, the bent portion 23 where the current concentrates can locally generate heat, and heat can be efficiently transferred to the insulating coating 12 in contact with the conductive member 20. In addition, since the covered electric wire 10 can be sandwiched between the base portion 21 and the folded portion 22, laser welding can be performed in a state in which the contact state between the covered electric wire 10 and the conductive member 20 is favorably maintained.

  In the present embodiment, the conductive member 20 is energized while pressurizing the conductive member 20 and the covered electric wire 10 by the pair of electrodes 30 and 31. Therefore, the device configuration for connecting the conductive member 20 and the round electric wire 11 can be simplified.

  As described above, the method of connecting the above-described covered electric wire is connectable even at a low cost even when the melting point temperature of the oxide film formed on the surface of the electric wire is sufficiently higher than the melting point temperature of the conductive member. This is a method of connecting a covered electric wire that can ensure good connection reliability.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In this embodiment, the example which removes the softened insulating film 12 by making it flow from the contact part with the electrically-conductive member 20 in the insulating film removal process was shown. However, the method for removing the insulating coating 12 is not limited to the above example, and for example, the insulating coating 12 may be removed by sublimation.

  In the present embodiment, the example in which the shape of the electric wire 11 has a circular cross section is shown. However, the shape of the electric wire 11 is not limited to the above example, and may be, for example, a rectangular cross section. However, the electric wire having a circular cross section has a smaller area in contact with the conductive member 20 than the electric wire having a rectangular cross section, so that the pressure applied to the insulating film 12 and the oxide film 13 is increased, and the insulating film 12 and oxide film 13 are easy to flow. Therefore, the shape of the electric wire 11 is preferably a circular cross section.

  In this embodiment, the example which employ | adopts the thing of a cross-sectional substantially U shape as the electrically-conductive member 20 was shown. However, the shape of the conductive member 20 is not limited to the above example, and for example, a flat plate shape can be adopted. However, as described above, since the conductive member 20 can be sandwiched between the base portion 21 and the folded portion 22 as long as the cross section is substantially U-shaped, the contact state between the covered wire 10 and the conductive member 20 is good. In this state, laser welding can be performed. Therefore, the shape of the conductive member 20 is preferably a substantially U-shaped cross section.

  In this embodiment, the example which employ | adopts the electrodes 30 and 31 which make a pair as a member which pressurizes the electrically-conductive member 20 and the covered electric wire 10, and flows an electric current through the electrically-conductive member 20 was shown. However, the member that pressurizes and energizes is not limited to the above example, and the operation of pressurizing and energizing may be performed by different members. However, in this case, the apparatus configuration for temporarily joining the conductive member 20 and the round electric wire 11 becomes complicated. Therefore, as shown in the above example, it is preferable to pressurize and energize the electrodes 30 and 31 that make a pair.

  In the present embodiment, an example is shown in which current flows from the electrode 31 to the electrode 30 through the folded portion 22, the bent portion 23, and the base portion 21 of the conductive member 20. However, a current may flow from the electrode 30 to the electrode 31 via the base portion 21, the bent portion 23, and the folded portion 22 of the conductive member 20.

  In this embodiment, the example which irradiates a laser beam via the folding | returning part 22 was shown. However, the direction in which the laser beam is applied to the contact surface between the round electric wire 11 and the conductive member 20 is not limited to the above example. For example, the laser beam may be applied to the contact surface via the base 21. good.

  In this embodiment, the example which employ | adopts a YAG laser as a laser beam was shown. However, the type of laser light is not limited to the above example.

It is a perspective view which shows the connection structure of the covered electric wire obtained by the connection method which concerns on 1st Embodiment. It is sectional drawing which follows the II-II line | wire of FIG. It is sectional drawing which shows a preparatory process. It is sectional drawing which shows an insulating film removal process. It is sectional drawing which shows a temporary joining process. It is sectional drawing which shows a laser welding process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Covered electric wire 11 ... Round shaped electric wire 12 ... Oxide film 13 ... Insulating film 20 ... Conductive member 23 ... Bending part 30, 31 ... Electrode

Claims (4)

A method of connecting a covered electric wire, wherein the covered electric wire is covered with an insulating coating and the conductive member has a melting point lower than the melting point of the oxide coating formed on the surface of the electric wire,
Insulating film removing step of removing the portion of the insulating film that comes into contact with the conductive member by pressurizing the conductive member so as to be in contact with a part of the insulating film, and by causing a current to flow through the conductive member to generate heat,
The conductive member is pressed so as to be in contact with the oxide film that has been exposed after the insulating film is removed, and a current is passed through the conductive member to generate heat, thereby contacting the conductive member in the oxide film. A temporary joining step of temporarily joining the contact surface between the electric wire and the conductive member that has been removed by removing the site and the oxide film is removed;
A method of connecting a covered electric wire, comprising: a laser welding step of irradiating a laser beam onto the temporarily contacted contact surface and melt-bonding the electric wire and the conductive member at the contact surface. The material of the electric wire is aluminum,
The method for connecting a covered electric wire according to claim 1, wherein the oxide film is alumina. The conductive member is formed by connecting a base portion and a folded portion facing the base portion by a bent portion,
The conductive member is in contact with a part of the insulating film by pressurizing the base and the folded portion while sandwiching the covered electric wire between the base and the folded portion. The connection method of the covered wire | conductor of Claim 1 or Claim 2.   The method for connecting a covered electric wire according to any one of claims 1 to 3, wherein the conductive member and the covered electric wire are pressurized by a pair of electrodes for causing a current to flow through the conductive member.

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