Ultrasonic welding jig, terminal-equipped electric cable manufacturing method, and terminal-equipped electric cable

Abstract

An ultrasonic welding jig includes: an anvil that supports a plate-like electric cable connection portion of a terminal; and a welding horn that is disposed so as to oppose the anvil, and in which a fitting groove is formed in an opposing surface, the fitting groove being a groove in which a portion of a core wire of an electric cable is fitted. In a state in which the core wire and the electric cable connection portion are clamped between the welding horn and the anvil, ultrasonic welding is performed by ultrasonically vibrating the welding horn in an axial direction of the core wire. In a bottom surface of the fitting groove of the welding horn, a plurality of slippage prevention grooves that are obliquely oriented and intersect an axis of the fitting groove are formed spaced apart in a direction of the axis of the fitting groove.

Claims

1. An ultrasonic welding jig for fixedly attaching a core wire of a core wire-equipped electric cable to a plate-shaped electric cable connection portion of a terminal through ultrasonic welding, the ultrasonic welding jig comprising: an anvil that supports the electric cable connection portion of the terminal; and a welding horn that is disposed so as to oppose the anvil, and in which a fitting groove is formed in an opposing surface, the fitting groove being a groove into which a portion of the core wire of the electric cable is fitted, wherein, in a condition in which the core wire and the electric cable connection portion are clamped between the welding horn and the anvil, ultrasonic welding is performed by ultrasonically vibrating the welding horn in an axial direction of the core wire, and in a bottom surface of the fitting groove of the welding horn, a plurality of slippage prevention grooves that are obliquely oriented and intersect an axis of the fitting groove are formed spaced apart in a direction of the axis of the fitting groove, and each of the slippage prevention grooves is nonintersecting with all other slippage prevention grooves on the bottom surface.

2. The ultrasonic welding jig according to claim 1, wherein the core wire is a stranded wire in which a plurality of strands are twisted together, and the slippage prevention grooves are oriented and intersect the axis of the fitting groove at an angle that is substantially equal to a twist angle of the strands that constitute the core wire.

3. The ultrasonic welding jig according to claim 2, wherein the slippage prevention grooves are formed so as to have a width that allows the strands of the core wire to be fitted therein.

4. An ultrasonic welding jig for fixedly attaching a core wire of a core wire-equipped electric cable to a plate-shaped electric cable connection portion of a terminal through ultrasonic welding, the ultrasonic welding jig comprising: an anvil that supports the electric cable connection portion of the terminal; and a welding horn that is disposed so as to oppose the anvil, and in which a fitting groove is formed in an opposing surface, the fitting groove being a groove into which a portion of the core wire of the electric cable is fitted, wherein, in a condition in which the core wire and the electric cable connection portion are clamped between the welding horn and the anvil, ultrasonic welding is performed by ultrasonically vibrating the welding horn in an axial direction of the core wire, in a bottom surface of the fitting groove of the welding horn, a plurality of slippage prevention grooves that are obliquely oriented and intersect an axis of the fitting groove are formed spaced apart in a direction of the axis of the fitting groove, the core wire is a stranded wire in which a plurality of strands are twisted together, the slippage prevention grooves are oriented and intersect the axis of the fitting groove at an angle that is substantially equal to a twist angle of the strands that constitute the core wire, the slippage prevention grooves are formed so as to have a width that allows the strands of the core wire to be fitted therein, and wherein, in the bottom surface of the fitting groove of the welding horn, in addition to the slippage prevention grooves, a plurality of auxiliary grooves that have a width that is smaller than the width of the slippage prevention grooves are formed so as to be oriented perpendicular to the slippage prevention grooves.

5. The ultrasonic welding jig according to claim 1, wherein a knurled groove is formed in the bottom surface of the fitting groove of the welding horn.

6. A terminal-equipped electric cable manufacturing method comprising: ultrasonically welding a core wire of an electric cable to a plate-shaped electric cable connection portion of a terminal by using the ultrasonic welding jig according to claim 1.

7. A terminal-equipped electric cable manufacturing method comprising: ultrasonically welding a core wire, which is a stranded wire, of an electric cable to a plate-shaped electric cable connection portion of a terminal by using the ultrasonic welding jig according to claim 2.

8. A terminal-equipped electric cable obtained by ultrasonically welding a core wire of a core wire-equipped electric cable to a plate-shaped electric cable connection portion of a terminal, wherein, on an outer surface of a welded portion of the core wire, a plurality of ridges that are obliquely oriented and intersect an axis of the core wire are formed spaced apart in an axial direction of the welded portion, and each of the ridges is nonintersecting with all other ridges on the outer surface.

9. A terminal-equipped electric cable obtained by ultrasonically welding a core wire of a core wire-equipped electric cable to a plate-shaped electric cable connection portion of a terminal, wherein, on an outer surface of a welded portion of the core wire, a plurality of ridges that are obliquely oriented and intersect an axis of the core wire are formed spaced apart in an axial direction of the welded portion, wherein the core wire is a stranded wire in which a plurality of strands are twisted together, and the ridges are oriented and intersect the axis of the core wire at an angle that is substantially equal to a twist angle of the strands that constitute the core wire.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a perspective view of an ultrasonic welding jig according to Embodiment 1 before ultrasonic welding is performed.

(2) FIG. 2 is a front view of the same before ultrasonic welding is performed.

(3) FIG. 3 is a side view of the same before ultrasonic welding is performed.

(4) FIG. 4 is a plan view of an end of a sheathed electric cable.

(5) FIG. 5 is a perspective view of a welding horn, which is turned upside down.

(6) FIG. 6 is a bottom view of the welding horn.

(7) FIG. 7 is a cross sectional view taken along the line VII-VII shown in FIG. 6.

(8) FIG. 8 is a cross sectional view taken along the line VIII-VIII shown in FIG. 6.

(9) FIG. 9 is a front view showing ultrasonic welding according to an embodiment.

(10) FIG. 10 is a side view showing ultrasonic welding according to the embodiment.

(11) FIG. 11 is a cross sectional view taken along the line XI-XI shown in FIG. 10.

(12) FIG. 12 is a cross sectional view taken along the line XII-XII shown in FIG. 9.

(13) FIG. 13 is a perspective view of a terminal-equipped electric cable.

(14) FIG. 14 is a plan view of the terminal-equipped electric cable.

(15) FIG. 15 is a side view of the terminal-equipped electric cable.

(16) FIG. 16 is a perspective view of a welding horn according to Embodiment 2, which is turned upside down.

(17) FIG. 17 is a bottom view of the welding horn.

(18) FIG. 18 is an enlarged cross sectional view taken along the line XVIII-XVIII shown in FIG. 17.

(19) FIG. 19 is a perspective view of a welding horn according to Embodiment 3, which is turned upside down.

(20) FIG. 20 is a bottom view of the welding horn.

DESCRIPTION OF EMBODIMENTS

Embodiment 1

(21) Embodiment 1 will be described with reference to FIGS. 1 to 15. As shown in FIG. 13, a terminal-equipped electric cable 10 according to the present embodiment has a structure in which a bus bar 20 (corresponding to a terminal) is connected to an end of a sheathed electric cable 11 (corresponding to an electric cable) through ultrasonic welding, and is used in, for example, a wiring portion such as a battery module mounted on an electric vehicle.

(22) As shown in FIGS. 2 and 4, the sheathed electric cable 11 has a structure in which the outer circumference of a core wire 12, which is composed of a stranded wire in which seven metal strands 13 are twisted together as shown in the diagrams, is covered with an insulation sheath 14 that is made of a synthetic resin. A predetermined length of the insulation sheath 14 has been stripped from an end of the sheathed electric cable 11 so as to expose the core wire 12.

(23) Specifically, as shown in FIG. 4, the core wire 12 is formed by twisting together seven strands 13, each having a diameter a, at a twist angle b.

(24) The bus bar 20 is made of metal. As shown in FIG. 1, the bus bar 20 has a plate-like shape that is rectangular when viewed in a plan view and has short sides that are longer than the length of the exposed core wire 12 of the sheathed electric cable 11 described above.

(25) An electric cable connection portion 21 is set at a center portion of the bus bar 20 in the length direction (the direction extending along the long sides) of the bus bar 20. As will be described later, the end of the core wire 12 of the sheathed electric cable 11 is placed on the electric cable connection portion 21 so as to extend in a direction extending along the short sides of the bus bar 20, and is fixedly attached to the electric cable connection portion 21 through ultrasonic welding.

(26) As shown in FIGS. 1 to 3, an ultrasonic welding jig 30 includes an anvil 31 and a welding horn 40 that is provided above the anvil 31 opposing the anvil 31.

(27) The anvil 31 is provided in a fixed manner, and the upper surface of the anvil 31 serves as a supporting surface 32 for supporting the electric cable connection portion 21 of the bus bar 20. Knurls 32A are formed on the supporting surface 32 to prevent slippage.

(28) The welding horn 40 includes, on its lower surface, a pressing portion 41 for pressing the end of the core wire 12 of the sheathed electric cable 11, the pressing portion 41 being formed in a protruding manner. The welding horn 40 is configured to be capable of moving in the vertical direction, which is a direction in which the welding horn 40 moves toward or away from the anvil 31, using a driving mechanism (not shown), and being ultrasonically vibrated in a direction extending along the short sides of the bus bar 20 as indicated by the arrows in FIG. 10, or in other words, in the axial direction of the core wire 12.

(29) The lower surface of the pressing portion 41 of the welding horn 40 serves as a pressing surface 42. As shown in FIGS. 5 to 8, in the pressing surface 42, a fitting groove 43, into which the upper side of a transverse cross section of the core wire 12 is fitted, is formed so as to extend over the entire length of the pressing surface 42 (the right left direction in FIG. 8). The fitting groove 43 is formed so as to also function as a positioning groove for the core wire 12. Specifically, as shown in FIG. 2, the fitting groove 43 is formed so as to have an arc-shaped cross section that has a diameter slightly larger than the diameter of the core wire 12.

(30) In the bottom surface of the fitting groove 43, as shown in FIG. 6, three slippage prevention grooves 45 that are obliquely oriented and intersect the axis of the fitting groove 43 are formed so as to be spaced apart at a predetermined interval in the axial direction of the fitting groove 43. Each slippage prevention groove 45 has an arc-shaped cross section (see FIG. 7), and is formed so as to extend over substantially the entire width of the bottom surface of the fitting groove 43.

(31) To be more specific, as shown in FIG. 6, a groove width A of each fitting groove 45 is set to be substantially equal to the diameter a of each strand 13 that constitutes the core wire 12 of the sheathed electric cable 11 (A≈a), and an intersection angle B of the slippage prevention grooves 45 relative to the axis of the fitting groove 43 is set to be substantially equal to the twist angle b of each strand 13 that constitutes the core wire 12 (B≈b).

(32) Also, a dimension substantially equal to the diameter a of each strand 13 is set as the interval between the fitting grooves 45.

(33) Next, an example of a procedure for manufacturing a terminal-equipped electric cable 10 will be described.

(34) As shown in FIGS. 1 to 3, in a state in which the welding horn 40 of the ultrasonic welding jig 30 is retracted to an upper position, the electric cable connection portion 21 of the bus bar 20 is placed on the supporting surface 32 of the anvil 31. Next, the exposed end of the core wire 12 of the sheathed electric cable 11 is placed on the electric cable connection portion 21 of the bus bar 20 that is supported on the anvil 31.

(35) When the bus bar 20 and the core wire 12 of the sheathed electric cable 11 have been set, the welding horn 40 is moved downward, and as shown in FIGS. 9 and 10, the core wire 12 is pressed against the electric cable connection portion 21 of the bus bar 20, with the core wire 12 fitting into the fitting groove 43 and being positioned by the fitting groove 43.

(36) As a result, the knurls 32A formed on the supporting surface 32 of the anvil 31 bite into the lower surface of the electric cable connection portion 21 of the bus bar 20, and the bus bar 20 is supported on the supporting surface 32 of the anvil 31 in a non-slip manner.

(37) On the other hand, the core wire 12 of the sheathed electric cable 11 is compressed and fitted into the fitting groove 43 formed in the pressing surface 42 of the welding horn 40, and at the same time, a total of three alternate strands 13 out of the strands 13 on an opposing surface of the core wire 12 that opposes the fitting groove 43 are fitted into the slippage prevention grooves 45 formed in the bottom surface of the fitting groove 43.

(38) After the pressing operation of the welding horn 40 has been performed in the manner described above, the welding horn 40 is ultrasonically vibrated in a direction indicated by the arrows shown in FIG. 10. Here, as described above, because three strands 13 out of the strands 13 that constitute the core wire 12 are fitted into the slippage prevention grooves 45 formed on the bottom surface of the fitting groove 43 over a long distance, the core wire 12 is ultrasonically vibrated together with the welding horn 40 in the axial direction of the core wire 12, without slippage occurring between the core wire 12 and the welding horn 40.

(39) That is, on the electric cable connection portion 21 of the bus bar 20 that is supported on the supporting surface 32 of the anvil 31 in a non-slip manner, the core wire 12 is ultrasonically vibrated efficiently in the axial direction, with the exposed portion of the core wire 12 of the sheathed electric cable 11 being appropriately pressed. At this time, once the oxide film is removed from the bonding surface between the electric cable connection portion 21 of the bus bar 20 and the core wire 12, atomic diffusion occurs in the bonding surface, and atomic binding occurs. As a result, the core wire 12 of the sheathed electric cable 11 is ultrasonically welded and fixedly attached to the electric cable connection portion 21 of the bus bar 20.

(40) After the welding step, the ultrasonic vibration of the welding horn 40 is stopped, and the welding horn 40 is retracted upward. As a result, as shown in FIGS. 13 to 15, a terminal-equipped electric cable 10 is obtained in which the core wire 12 of the sheathed electric cable 11 has been fixedly attached to the electric cable connection portion 21 of the bus bar 20 through ultrasonic welding.

(41) In the terminal-equipped electric cable 10, a portion (welded portion 15) of the core wire 12 that has been ultrasonically welded to the electric cable connection portion 21 of the bus bar 20 is formed in a rod-like shape that has an arc-shaped cross section that conforms to the fitting groove 43 formed in the pressing surface 42 of the welding horn 40. Also, on the outer circumferential surface of the welded portion 15, three ridges 16, which have arc-shaped cross sections that conform to the slippage prevention grooves 45 formed on the bottom surface of the fitting groove 43, are formed so as to be obliquely oriented and intersect the axis of the welded portion 15 at an angle that is substantially equal to the twist angle b of each strand 13, and are formed spaced apart in the axial direction of the welded portion 15.

(42) As described above, in the present embodiment, as a slippage prevention means for preventing slippage between the welding horn 40 of the ultrasonic welding jig 30 and the core wire 12 of the sheathed electric cable 11, a structure is employed in which a fitting groove 43 that has an arc-shaped cross section and into which a portion of a transverse cross section of the core wire 12 is fitted is formed in the pressing surface 42 of the welding horn 40, and three slippage prevention grooves 45, which each have a groove width A that allows a strand 13 to be fitted therein, are formed in the bottom surface of the fitting groove 43 so as to be obliquely oriented and intersect the axis of the fitting groove 43 at an angle B that is substantially equal to the twist angle b of a strand 13, and to be spaced apart in the axial direction of the fitting groove 43.

(43) Accordingly, a long region of the strands 13 that constitute the core wire 12 is fitted into the slippage prevention grooves 45, and thus a high level of slippage preventability is exhibited even in an embodiment in which the pressing force on the core wire 12 is not increased. That is, it is possible to perform ultrasonic welding properly while suppressing damage to the core wire 12. As a result, it is possible to obtain a high fixing force in the welded portion.

Embodiment 2

(44) Embodiment 2 will be described with reference to FIGS. 16 to 18. In Embodiment 2, an improvement has been added to a slippage prevention structure for preventing slippage between a welding horn 40X and the core wire 12 of the sheathed electric cable 11. Specifically, in the bottom surface of the fitting groove 43 formed on the pressing surface 42 of the welding horn 40X, in addition to three slippage prevention grooves 45 as shown in Embodiment 1 described above, a plurality of (fifteen in the diagram) auxiliary grooves 47 that have a width that is smaller than that of the slippage prevention grooves 45 are formed so as to be oriented perpendicular to the slippage prevention grooves 45. As shown in FIG. 18, the auxiliary grooves 47 are formed in the form of slits.

(45) Embodiment 2 is configured such that, when the core wire 12 of the sheathed electric cable 11 is compressed and fitted into the fitting groove 43 through the pressing operation of the welding horn 40X, in addition to a predetermined number of strands 13 out of the strands 13 that constitute the core wire 12 being fitted into the slippage prevention grooves 45, the auxiliary grooves 47 abut against the strands 13 at a right angle to the strands 13.

(46) That is, in addition to a long region of the strands 13 that constitute the core wire 12 being fitted into the slippage prevention grooves 45, the auxiliary grooves 47 produce a so-called edge effect in which the groove edges of the auxiliary grooves 47 bite into the strands 13, and thus an even higher level of slippage preventability is exhibited overall.

Embodiment 3

(47) Embodiment 3 will be described with reference to FIGS. 19 and 20. In Embodiment 3, yet another slippage prevention structure is shown in which a knurled groove 50 is formed in the bottom surface of the fitting groove 43 formed on the pressing surface 42 of a welding horn 40Y.

(48) The knurled groove 50 is a groove in which a plurality of slits 51 that are similar to the auxiliary grooves 47 shown in Embodiment 2 above are formed in a grid pattern through cutting.

(49) To be specific, the knurled groove 50 is formed such that a first slit group 52P including a plurality of slits 51 that are provided at a predetermined pitch and so as to be obliquely oriented and intersect the axis of the fitting groove 43 at an angle that is substantially equal to the twist angle b of a strand 13 (see FIG. 4) and a second slit group 52Q including a plurality of slits 51 that are provided at the same pitch as the slits 51 of the first slit group 52P and so as to be oriented perpendicular to the slits 51 of the first slit group 52P are provided in a grid pattern as described above.

(50) In Embodiment 3, when the core wire 12 of the sheathed electric cable 11 is compressed and fitted into the fitting groove 43, an edge effect is produced in which the groove edges of the slits 51 of the first slit group 52P latch onto a long region of the strands that constitute the core wire 12, and the groove edges of the slits 51 of the second slit group 52Q that are perpendicular to the slits 51 of the first slit group 52P bite into the strands 13. Accordingly, the slippage preventability of preventing slippage between the welding horn 40Y and the core wire 12 of the sheathed electric cable 11 can be effectively exhibited.

Other Embodiments

(51) The technology disclosed in this specification is not limited to the embodiments described above with reference to the drawings. For example, embodiments as described below are also encompassed in the scope of the technology disclosed in this specification.

(52) (1) The terminal is not limited to a bus bar used as an example in the embodiments given above, and it is possible to use a terminal that has a structure in which a plate-like electric cable connection portion is provided rearward of a terminal connection portion that is connected to another terminal or the like.

(53) (2) In the embodiments given above, an example has been described in which the core wire exposed at an end of the sheathed electric cable is ultrasonically welded, but the present invention is also applicable to a case where the core wire that is exposed at a position midway in the lengthwise direction of the sheathed electric cable is ultrasonically welded.

(54) (3) In the embodiments given above, an example has been described in which the core wire is formed by twisting seven strands together, but the number of strands that are twisted together may be any number.

(55) (4) The electric cable may include a bare stranded wire that does not include an insulation sheath.

(56) (5) The width of the slippage prevention grooves that are formed in the bottom surface of the fitting groove of the welding horn may be set to any width dimension that is smaller than a maximum width that is set to a width at which the strands that constitute the core wire can substantially tightly fit therein. Also, the number of slippage prevention grooves, and the interval between slippage prevention grooves may also be set as appropriate according to conditions such as the diameter of the strands that constitute the core wire.

(57) (6) The core wire of the electric cable is not limited to a stranded wire, and may be a single-core wire, or a straight wire in which a plurality of metal strands are linearly bundled. Even when a single-core wire or a straight wire is used, as long as the slippage prevention grooves are formed so as to be obliquely oriented and intersect the axis of the fitting groove, the groove edges of the slippage prevention grooves latch onto the outer circumference of the core wire over a long region, and thus a high level of slippage preventability is exhibited.

LIST OF REFERENCE NUMERALS

(58) 10 Terminal-equipped electric cable

(59) 11 Sheathed electric cable (electric cable)

(60) 12 Core wire

(61) 13 Strand

(62) 15 Welded portion

(63) 16 Ridge

(64) 20 Bus bar (terminal)

(65) 21 Electric cable connection portion

(66) 30 Ultrasonic welding jig

(67) 31 Anvil

(68) 40, 40X, 40Y Welding horn

(69) 42 Pressing surface (opposing surface)

(70) 43 Fitting groove

(71) 45 Slippage prevention groove

(72) 47 Auxiliary groove

(73) 50 Knurled groove

(74) 51 Slit

(75) a Diameter (of strand 13)

(76) b Twist angle (of strand 13)

(77) A Groove width (of slippage prevention groove 45)

(78) B Intersection angle (of slippage prevention groove 45)