JP2005319497A - Manufacturing method of wire with terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic welding method of a terminal tap with a core wire by which a ultrasonic welding strength is enhanced. <P>SOLUTION: The dimension between a pressing face 23 of a welding tip 22 and a bottom wall 12a of a terminal tap 11 when a core wire 31 is pressed therebetween is set so that a part corresponding to both ends is smaller than a part corresponding to a central part of the core wire 31. When the ultrasonic welding is performed while applying compression to the core wire 31 of a substantially circular section by the welding tip 22, the pressure is uniformly applied as a whole even when the density of strands 31a to constitute the core wire 31 is small at both ends, an excellent welded state can be obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing an electric wire with a terminal, and more specifically, to improve the bonding strength by ultrasonic welding to a terminal fitting while uniformly compressing a core wire composed of a plurality of stranded wires. .

Conventionally, when joining a core wire in which a plurality of strands are twisted together to a terminal, there is one described in Patent Document 1 using ultrasonic welding. Generally, in order to join a core wire and a terminal by ultrasonic welding, as shown in FIGS. 9A and 9B, first, an electric wire connecting portion 3 of a terminal fitting 2 is placed on an anvil 1, and this electric wire connecting portion. The core wire Wa exposed by peeling off the end of the electric wire W is placed on the upper surface of 3. Next, the core wire Wa on the wire connection portion 3 is pressed by the welding tip 4 to apply ultrasonic vibration so that the core wire Wa and the terminal fitting 2 are sandwiched between the anvil 1 and the core wire Wa. It joins to the electric wire connection part 3 of 2. As shown in FIG.
JP 2000-20642 A

  The core wire Wa is configured such that a plurality of strands Wb are twisted to form a substantially circular cross section, while the wire connection portion 3 of the terminal fitting 2 is perpendicular to the flat bottom wall 3a on which the core wire Wa is placed from both sides. It is comprised from the side walls 3b and 3c which were started up. On the other hand, since the cross-sectional shape of the pressing surface 4a of the welding tip 4 is a planar shape facing the bottom wall 3a of the terminal fitting 2, the core wire Wa placed on the bottom wall 3a is pressed by the welding tip 4. When compressing with the surface 4a, a difference arises in the compression condition between the center part A and the both side parts B of the core wire Wa. That is, since the core wire Wa has a substantially circular cross section, the center portion A has a large number of strands Wb existing in the compression direction, whereas the both side portions B have a very small number of strands Wb. .

  For this reason, when the core wire Wa is compressed between the bottom wall 3a by the welding tip 4, the strand Wb of the central portion A moves to the side portions B to some extent, but is not in a uniform state. The ultrasonic welding is performed while the number of the wires Wb is small. When the cross section of the joined portion between the core wire Wa and the wire connecting portion 3 joined in this way is observed, as shown in FIG. 9B, the strands Wb are crushed at the central portion A, and there is no gap between them. However, in both side portions B, it was confirmed that each wire Wb was not sufficiently crushed and there was a gap C between adjacent wires Wb. That is, at both side portions B, there is a problem that welding between the core wire Wa and the terminal fitting 2 becomes insufficient, and sufficient joint strength cannot be exhibited. On the other hand, if the compression by the welding tip 4 is increased or the ultrasonic vibration time is set to be long in order to compensate for the insufficient compression at the both side portions B, the center portion A of the core wire Wa becomes overcompressed and the wire Wb after joining There is a possibility that breakage may occur. After all, there is a problem in that sufficient bonding strength cannot be obtained also in this case.

  The present invention has been made in view of the above-described problems, and has a terminal-attached electric wire capable of uniformly compressing a core wire between a welding tip and a bottom wall of a terminal fitting, thereby increasing the joining strength of ultrasonic welding. An object of the present invention is to provide a manufacturing method.

In order to solve the above-mentioned problems, an electric wire formed by surrounding a core wire having a substantially circular cross section obtained by twisting a plurality of strands with an insulating coating, and a bottom wall for receiving the core wire exposed by peeling off an end portion of the electric wire And a terminal metal fitting having a substantially U-shaped cross-section electric wire connecting portion formed on both sides of the bottom wall and ultrasonically welded between the anvil and the welding tip. A method of manufacturing an electric wire with a terminal,
The dimensions between the pressing surface of the welding tip and the bottom wall of the terminal fitting when the core wire is compressed are set so that the portions corresponding to both sides are smaller than the portion corresponding to the central portion of the core wire. And providing a method of manufacturing a terminal-attached electric wire characterized by ultrasonic welding.

  In this way, when compressing the core wire between the welding tip and the bottom wall of the terminal fitting, the pressing surface of the welding tip and the bottom wall of the terminal fitting are lower than the central portion at both sides where the number of strands is small. Since the compression interval is narrowed, the wires can be joined in a uniform state without being insufficiently compressed.

Specifically, the welding tip has a shape in which both end portions of the pressing surface bulge toward the anvil rather than the central portion.
If comprised in this way, the both ends of a core wire with a low density compared with a center part can be compressed reliably by the both ends which the pressing surface in the welding tip expanded, and the joining state without a clearance gap can be obtained. In addition, as a shape of the pressing surface of a welding tip, various shapes are employable according to the compression state of a core wire, such as an inverted concave shape, a mountain shape, and a circular arc shape.

Moreover, you may make it use the said terminal metal fitting of the shape which the center part of a bottom wall swells on the opposite side to the welding tip which opposes rather than the both-sides wall side.
In this way, since the pressing surface of the welding tip may remain flat, during the core wire compression operation between the welding tip and the bottom wall of the terminal fitting, each of the strands of the core wire that contacts the pressing surface While smoothly moving in the direction of both sides, it is possible to prevent the center portion having a high density of strands from being received by the bulged portion of the bottom wall and causing over-compression. In addition, as the cross-sectional shape of the bottom wall of the terminal fitting, depending on the compression state of the core wire, such as a shape that gently curves downward and bulges toward the central portion, a V shape, a shape having a concave portion in the central portion, etc. Various shapes can be employed.

  As is apparent from the above description, according to the method for manufacturing a terminal-attached electric wire of the present invention, ultrasonic welding can be performed in a uniform state from the central portion to both side portions at the joint portion between the core wire and the terminal fitting. Therefore, the joint strength between the core wire and the terminal fitting can be increased.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1-5 shows 1st Embodiment of this invention, and shows the process of manufacturing the electric wire 10 with a terminal by ultrasonically welding the terminal of the electric wire 30 to the terminal metal fitting 11 using an ultrasonic welding machine. Yes. The ultrasonic welding machine includes an anvil 21 on which the terminal fitting 11 is placed, and a welding tip 22 that faces the upper portion of the anvil 21 and sandwiches the terminal fitting 11 and the electric wire 30 between the anvil 21. By applying ultrasonic vibration to the terminal fitting 11 and the electric wire 30 between the chip 22 and the anvil 21, both are joined.

  The electric wire 30 to be welded to the terminal fitting 11 is formed by covering a core wire 31 formed by twisting a plurality of strands 31a into a circular cross section with an insulating coating 33 made of a synthetic resin. The core wire 31 is exposed by peeling over a predetermined length necessary for joining to the wire 11.

  The terminal fitting 11 includes not only a general male or female terminal but also a terminal used as a ground terminal or the like, and has an electric wire connecting portion 12 to which a core wire 31 is to be fixed. The electric wire connecting portion 12 includes a flat bottom wall 12a and side walls 12b and 12c extending vertically upward from both sides of the bottom plate portion 22a and having a substantially U-shaped cross section.

  The anvil 21 is fixed to a main body base of an ultrasonic welder (not shown), and a receiving portion 21a for receiving and positioning the wire connecting portion 12 of the terminal fitting 11 is recessed in the upper portion. The accommodating portion 21a has a concave cross section with an open upper surface, and can be held in surface contact with the bottom wall 12a and the side walls 12b and 12c of the electric wire connecting portion 12 so that the electric wire connecting portion 12 can be accommodated and held without backlash. It is a shape.

  The welding tip 22 has a block shape having a width that allows entry into the electric wire connection portion 12 of the terminal fitting 11, and can be operated in the vertical direction so as to face the upper portion of the anvil 21. The lower surface of the welding tip 22 is a pressing surface 23 against the core wire 31, and the pressing surface 23 bulges into a small block shape with the central pressing portion 23a of the flat central portion and both ends facing downward (anvil 21 side). And an end pressing portion 23b. Thereby, when compressing the core wire 31 between the welding tip 22 and the bottom wall 12a of the terminal metal fitting 11, as shown in FIG. 2, the center press part 23a corresponding to the center part A of the core wire 31, and the bottom wall 12a The dimension Lb between the end pressing part 23b corresponding to the both ends B of the core wire 31 and the bottom wall 12a is set to be smaller than the dimension La between the two.

Next, the manufacturing method of the electric wire with a terminal by a 1st embodiment is explained.
First, as shown in FIG. 1, the core wire 31 exposed by peeling off the end of the electric wire 30 is placed in the electric wire connecting portion 12 of the terminal fitting 11 accommodated in the accommodating portion 21 a of the anvil 21. At this time, as shown in FIG. 2, the core wire 31 is placed on the bottom wall 12 a in a substantially circular cross-section by a bundle of strands 31 a, and the welding tip 22 of the ultrasonic welder is located above the core wire 31. Is waiting in the raised position. Next, as shown in FIG. 3A, when the welding tip 22 is lowered toward the anvil 21, first, the central pressing portion 23 a comes into contact with the outer periphery of the central portion A of the core wire 31. In addition to being compressed, the central strand 31a is pushed to both side portions B along with this compression. In this way, a part of the strands 31a moves to the both side portions B, but the number of the strands 31a in the both side portions B is still smaller than that of the central portion A and is in a low density state.

  However, in the present embodiment, since the end pressing portions 23b are provided at both ends of the pressing surface 23, the distance between the pressing surface 23 and the bottom wall 12a in both side portions B is narrower than the central portion A, thereby A sufficient pressing force can be applied to the strands 31a having a low density in the portion B as in the central portion A. Subsequently, the welding tip 22 is moved back and forth at a high speed in a state where the pressing force of the welding tip 22 is applied to the core wire 31, so that the contact portion between the welding tip 22 and the core wire 31 and the wire of the core wire 31 and the terminal fitting 11 are obtained. Ultrasonic vibration is applied to the contact portion with the inner surface of the connection portion 12. As a result, each wire 31a gradually rises in temperature due to frictional heat and softens, and as shown in FIG. 3B, the softened wire 31a is deformed so as to be crushed by the pressing force of the welding tip 22. Go. Such softening deformation of the wire 31a spreads over the entire core wire 31, and is finally joined to each other between the adjacent wires 31a and the inner surface of the wire connecting portion 12. As described above, in this embodiment, by using the welding tips 22 in which the end pressing portions 23b are bulged downward at both ends of the pressing surface 23, both side portions of the core 31 having a low density of the strands 31a. Also in B, ultrasonic welding can be performed on the wire connecting portion 12 while applying a sufficient pressing force to each element wire 31a.

  4 and 5 show modifications of the first embodiment, in which the shape of the pressing surface 23 of the welding tip 22 is variously modified.

In the welding tip 22A of FIG. 4A, the central pressing portion 23Aa on the pressing surface 23A is formed in a mountain shape so as to be tapered to the end pressing portion 23Ab at both ends.
The welding tip 22B in FIG. 4B has a central pressing portion 23Ba of the pressing surface 23B having a mountain shape, and the end pressing portion B23b is formed as an extended portion that transitions from the central pressing portion 23Ba to a taper shape.

In the welding tip 22C of FIG. 5A, the central pressing portion 23Ca in the width region of approximately 1/3 of the pressing surface 23C is a flat surface, and the end pressing portion 23Cb is tapered from both ends of the central pressing portion 23Ca. It is formed as an extended part.
In the welding tip 22D of FIG. 5B, the pressing surface 23D is moved to the end pressing portions 23Db at both ends as curved surfaces that are curved inward.
In any of the above modifications, the end pressing portions 23Ab to 23Db of the welding tips 22A to 22D are bulged downward by the central pressing portions 23Aa to 23Da, so the density of the strands 31a at both ends B of the core wire 31 is increased. A sufficient pressing force can be applied to a low portion of the. The shapes of the welding tips 22 </ b> A to 22 </ b> D in these modified examples are selected as appropriate in accordance with the moving state to the both side portions B during the pressing action on the core wire 31 and the degree of congestion, and the optimum shape is selected.

6 to 8 show a second embodiment. In this embodiment, the welding tip 122 is a general shape having a flat pressing surface 123, while the shape of the electric wire connecting portion 112 of the terminal fitting 111 is changed. Is added. That is, a pressure absorbing portion 113 is formed in which the central portion of the bottom wall 112a of the wire connecting portion 112 is bulged below the side walls 111b and 111c (on the opposite side to the opposing welding tip 122). By using such a terminal fitting 111, when the core wire 31 is compressed between the welding tip 122 and the bottom wall 112 a of the terminal fitting 111, the pressing surface 123 and the pressure absorbing portion 113 against the central portion A of the core wire 31. The dimension L1b between the pressing surfaces 123 on both side portions B of the core wire 31 is set to be smaller than the dimension L1a between them. In addition, the bottom surface of the accommodating portion 121a in the anvil 121 has a shape in which the central portion is recessed corresponding to the shape of the wire connecting portion 112 of the terminal fitting 111.
Since other configurations are the same as those of the first embodiment, the same reference numerals are given and description thereof is omitted.

Next, the manufacturing method of the electric wire with a terminal by the said 2nd Embodiment is demonstrated.
As shown in FIG. 6 (B), the welding tip 122 is lowered and the pressing is applied to the core wire 31 placed on the wire connecting portion 112 of the terminal fitting 111. As a result, the pressing surface 123 comes into contact with the outer periphery of the center portion A of the core wire 31 so that each strand 31a is compressed in the vertical direction, and the center strand 31a is pushed to both side portions B accordingly. Thus, although a part of the strand 31a moves to the both side portions B, the number of the strands 31a in the both side portions B is still lower than that of the central portion A and is in a low density state.
In the present embodiment, since the terminal fitting 111 having a shape in which the center portion of the bottom wall 112a of the electric wire connecting portion 112 is bulged below the both side walls 112b and 112c is used, the pressing surface 123 of the welding tip 122 and The space | interval between the both ends of the bottom wall 112a of the electric wire connection part 112 is narrower than the center part. For this reason, the central part A having a high density of the strands 31a does not become over-compressed, and can be applied to each strand 31a with a uniform compressive force over the entire range in balance with both ends B having a low density. .

  As in the first embodiment, the core wire 31 is adjacent to the core wire 31 by applying ultrasonic vibration to the core wire 31 through the welding tip 122 in a state where the pressing force of the welding tip 122 is applied to the core wire 31. It is possible to uniformly join the 31a to each other and the inner surface of the wire connecting portion 112.

7 and 8 show modifications of the second embodiment, in which the shape of the bottom wall 112a of the terminal fitting 111 is variously modified.
The bottom wall 112Aa of FIG. 7A employs a V-shaped shape in which the pressure absorbing portion 113A is recessed in a tapered shape from both sides toward the center.
The bottom wall 112Ba of FIG. 7 (B) employs an inverted trapezoidal shape in which the pressure absorbing portion 113B is recessed from both sides in a tapered shape toward the center and has a flat portion.
The bottom wall 112Ca of FIG. 8 employs a shape in which the central portion is recessed in a stepped shape as the pressure absorbing portion 113C.

  In any of the above modifications, the shape of the bottom wall 112a of the wire connection portion 112 in the terminal fitting 111 is provided with the pressure absorbing portions 113A to 113C having a depressed central portion, so that the strands 31a at both ends B of the core wire 31 are provided. A sufficient pressing force can be applied to a portion having a low density. In these modified examples, an optimum shape is set by appropriately selecting according to the moving state to the both side portions B during the pressing action on the core wire 31 and the degree of congestion.

  In addition, although the employment | adoption of the protrusion shape of the edge part press part of the welding tip in the said 1st Embodiment and adoption of the press absorption part of the terminal metal fitting in the said 2nd Embodiment showed the example applied separately, both were shown. It may be provided at the same time. Moreover, the protrusion dimension of the edge part press part of the welding tip in 1st Embodiment, and the hollow dimension of the press absorption part of the terminal metal fitting in 2nd Embodiment are the number of strands in a core wire, a magnitude | size, and the press action by a welding tip According to the situation of movement to both sides at the time, the pressing force for the entire area of the core wire is adjusted appropriately so that it acts uniformly.

It is a perspective view which shows the ultrasonic welding process in 1st Embodiment of the manufacturing method of the electric wire with a terminal of this invention. It is sectional drawing which shows the standby state of a welding tip. (A) (B) is sectional drawing which shows the compression process by a welding tip. (A) (B) is sectional drawing which shows the modification of 1st Embodiment. (A) (B) is sectional drawing which shows the other modification of 1st Embodiment. (A) is sectional drawing of the standby state of the welding tip in 2nd Embodiment, (B) is sectional drawing of a compression process. (A) (B) is sectional drawing which shows the modification of 2nd Embodiment. It is sectional drawing which shows the other modification of 2nd Embodiment. (A) (B) is sectional drawing which shows the manufacturing method of the electric wire with a terminal by the ultrasonic welding of a prior art example.

Explanation of symbols

10 Electric wire with terminal 11, 111 Terminal fitting 12, 112 Electric wire connection part 12a, 112a Bottom wall 12b, 12c, 112b, 112c Side wall 113 Press absorbing part 21 Anvil 22, 22A, 22B, 22C, 22D Welding tip 23, 23A, 23B , 23C, 23D Press surface 30 Electric wire 31 Core wire 31a Wire 32 Insulation coating A Center portion B Both sides

Claims (3)

An electric wire formed by surrounding a core wire having a substantially circular cross section obtained by twisting a plurality of strands with an insulation coating, a bottom wall for receiving the core wire exposed by peeling off an end portion of the electric wire, and both sides of the bottom wall A method of manufacturing a terminal-attached electric wire by ultrasonic welding a terminal fitting provided with an electric wire connection portion having a substantially U-shaped cross-section composed of an upright side wall and sandwiched between an anvil and a welding tip. Because
The dimensions between the pressing surface of the welding tip and the bottom wall of the terminal fitting when the core wire is compressed are set so that the portions corresponding to both sides are smaller than the portion corresponding to the central portion of the core wire. A method for manufacturing a terminal-attached electric wire, wherein ultrasonic welding is performed.   The method for manufacturing a terminal-attached electric wire according to claim 1, wherein the welding tip has a shape in which both side portions of the pressing surface bulge toward the anvil rather than the central portion.   The method for manufacturing a terminal-attached electric wire according to claim 1 or 2, wherein the terminal fitting has a shape in which a central portion of the bottom wall bulges to the opposite side of the welding tip from both side walls.

Images