Patent Publication Number: US-8118209-B2

Title: Ultrasonic welding apparatus and ultrasonic welding method

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention relates to an ultrasonic welding apparatus and an ultrasonic welding method, and particularly to the ultrasonic welding apparatus for ultrasonically welding a core wire constructed by bundling plural strands to a terminal clamp, and the ultrasonic welding method. 
     2. Description of the Related Art 
     An automobile as a mobile unit is equipped with various electronic devices. In the automobile, a wire harness is cabled in order to transmit, for example, a control signal from a controller or electric power from a power source such as a battery to the electronic devices. The wire harness includes plural electric wires, a terminal clamp attached to a terminal of the electric wires, etc. 
     Each of the electric wires includes a core wire constructed by bundling plural conductive strands, and an insulating coat part for coating the core wire. The core wire exposed by eliminating the coat part of a terminal of this electric wire is welded to the terminal clamp. The core wire of the electric wire is connected to the terminal clamp using, for example, an ultrasonic welding apparatus (see Patent Reference 1). 
     For example, an ultrasonic welding apparatus  101  as shown in  FIG. 3  is proposed in Patent Reference 1. As shown in  FIG. 3 , the ultrasonic welding apparatus  101  includes an anvil (not shown) equipped with a terminal clamp  103  including an electrical contact part  131  in which a connection hole  131   a  connected to a connection terminal disposed in the electronic device is disposed and a core wire weld part  132  which ranges to the electrical contact part  131  and stacks a core wire  121  constructed by bundling plural strands, and a chip  107  opposed to the anvil. Ultrasonic vibration is applied to the chip  107  by a vibrator (not shown). The ultrasonic welding apparatus  101  moves the chip  107  toward the core wire  121  and the core wire weld part  132  (as shown by an arrow). Consequently, the core wire  121  is mutually connected to the terminal clamp  103  by applying ultrasonic vibration in a state of pinching the core wire  121  and the core wire weld part  132  between the chip  107  and the anvil and pressurizing the core wire  121  and the core wire weld part  132  in a direction of approaching each other. 
     Patent Reference 1: JP-A-2007-305314 
     However, in the ultrasonic welding apparatus  101  shown in Patent Reference 1 described above, there was fear that a portion of the terminal of the core wire  121  moves (protrudes) to a place overlapping with the electrical contact part  131  in the case of applying ultrasonic vibration in a state of pinching the core wire  121  and the core wire weld part  132  between the chip  107  and the anvil and pressurizing the core wire  121  and the core wire weld part  132  in the direction of approaching each other. As a result of this, in the case of connecting the electronic device to the terminal clamp  103 , an operator must screw a nut through a bolt after the connection terminal of the electronic device is stacked on the connection hole  131   a  of the terminal clamp  103  and a portion of the terminal of the protruding core wire  121  is eliminated so as not to be pinched between the electrical contact part  131  and the head of the bolt, and there was a problem that it takes time to do attachment work for attaching the wire harness to the electronic device. Also, there was a problem of spoiling beauty of the wire harness attached to the electronic device in a state in which the portion of the core wire  121  protrudes thus. 
     SUMMARY 
     Therefore, an object of the invention is to provide an ultrasonic welding apparatus and an ultrasonic welding method for manufacturing a wire harness capable of preventing spoilage of beauty and improving attachment workability in the case of being attached to an electronic device. 
     In an ultrasonic welding apparatus including an anvil equipped with a terminal clamp for disposing an electrical contact part connected to an electronic device and a core wire weld part which ranges to the electrical contact part and stacks a core wire constructed by bundling plural strands, and a chip which is disposed in a position opposed to the anvil and mutually welds the core wire to the core wire weld part by applying ultrasonic vibration in a state of pinching the core wire and the core wire weld part between the anvil and the chip and pressurizing the core wire and the core wire weld part in a direction of approaching each other, the ultrasonic welding apparatus of the invention is characterized by including a core wire protrusion prevention wall which is disposed in a position close to a terminal of the core wire and prevents the terminal of the core wire from moving to a place overlapping with the electrical contact part. 
     In an ultrasonic welding method including a first step of equipping an anvil with a terminal clamp for disposing an electrical contact part connected to an electronic device, a second step of stacking a core wire constructed by bundling plural strands on a core wire weld part ranging to the electrical contact part, and a third step of mutually welding the core wire to the core wire weld part by applying ultrasonic vibration in a state of pinching the core wire and the core wire weld part between the anvil and the chip and pressurizing the core wire and the core wire weld part in a direction of approaching each other, the ultrasonic welding method of the invention is characterized in that in the second step, a terminal of the core wire is arranged in a position close to a core wire protrusion prevention wall for preventing the terminal of the core wire from moving to a place overlapping with the electrical contact part. 
     According to the ultrasonic welding apparatus of the invention, the ultrasonic welding apparatus includes the core wire protrusion prevention wall which is disposed in the position close to the terminal of the core wire and prevents the terminal of the core wire from moving to the place overlapping with the electrical contact part, so that in the case of applying ultrasonic vibration in a state of pinching the core wire and the core wire weld part between the anvil and the chip and pressurizing the core wire and the core wire weld part in the direction of approaching each other, a portion of the terminal of the core wire is welded to the terminal clamp without moving (protruding) to the place overlapping with the electrical contact part, with the result that an operator can screw a nut through a bolt after the connection terminal of the electronic device is stacked on the connection hole of the terminal clamp in the case of connecting the electronic device to the terminal clamp, so that the ultrasonic welding apparatus for manufacturing the wire harness for improving attachment workability in the case of being attached to the electronic device can be provided. 
     Also, a portion of the terminal of the core wire is attached to the electronic device in a state of being welded to the terminal clamp without moving (protruding) to the place overlapping with the electrical contact part, so that the ultrasonic welding apparatus for manufacturing the wire harness for preventing spoilage of beauty can be provided. 
     According to the ultrasonic welding method of the invention, in the second step, the terminal of the core wire is arranged in the position close to the core wire protrusion prevention wall for preventing the core wire from moving to the place overlapping with the electrical contact part, so that in the case of applying ultrasonic vibration in a state of pinching the core wire and the core wire weld part between the anvil and the chip and pressurizing the core wire and the core wire weld part in the direction of approaching each other, a portion of the terminal of the core wire is welded to the terminal clamp without moving (protruding) to the place overlapping with the electrical contact part, with the result that an operator can screw a nut through a bolt after the connection terminal of the electronic device is stacked on the connection hole of the terminal clamp in the case of connecting the electronic device to the terminal clamp, so that the ultrasonic welding method for manufacturing the wire harness for improving attachment workability in the case of being attached to the electronic device can be provided. 
     Also, a portion of the terminal of the core wire is attached to the electronic device in a state of being welded to the terminal clamp without moving (protruding) to the place overlapping with the electrical contact part, so that the ultrasonic welding method for manufacturing the wire harness for preventing spoilage of beauty can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an explanatory diagram explaining ultrasonic welding work of an ultrasonic welding apparatus shown in one embodiment of the invention, and is a partially sectional side view showing a situation in which an anvil (not shown) is equipped with a terminal clamp for stacking a core wire and the terminal clamp is pressurized by a chip. 
         FIG. 2  is a top view showing a state of equipping the ultrasonic welding apparatus shown in  FIG. 1  with the terminal clamp. 
         FIG. 3  is a perspective view showing a situation in which a conventional ultrasonic welding apparatus is equipped with a terminal clamp for stacking a core wire and the terminal clamp is pressurized by a chip. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One embodiment of the invention will hereinafter be described with reference to  FIGS. 1 and 2 . An automobile as a mobile unit is equipped with various electronic devices. In the automobile, a wire harness  10  is cabled in order to transmit, for example, a control signal from a controller or electric power from a power source such as a battery to the electronic devices. The wire harness  10  includes plural electric wires  2 , and a terminal clamp  3  attached to a terminal of the electric wires  2 . 
     The ultrasonic welding apparatus  1  is used for electrically connecting the electric wire  2  to the terminal clamp  3  mutually. A cross-sectional shape of the electric wires  2  is formed in a round shape. The electric wire  2  includes a core wire  21  constructed by bundling plural strands made of conductive metal such as copper or copper alloy, and an insulating coat part  22 . The coat part  22  is made of an insulating synthetic resin, and coats the core wire  21 . The core wire  21  exposed by eliminating the coat part  22  of a terminal of this electric wire  2  is mutually welded to the terminal clamp  3 . 
     The terminal clamp  3  is obtained by bending a metal plate material punched in a predetermined shape, and integrally includes an electrical contact part  31  in which a connection hole  31   a  connected to a connection terminal disposed in the electronic device is disposed, a core wire weld part  32  to which the core wire  21  is welded, and a core wire movement part  33  disposed between the electrical contact part  31  and the core wire weld part  32 . That is, the core wire weld part  32  ranges to the electrical contact part  31 . 
     The core wire weld part  32  includes a bottom wall part  34  for stacking the core wire  21 , and a pair of erect wall parts  35  which are erected from both edges of a width direction of this bottom wall part  34  and position the core wire  21  between the mutual erect wall parts. Then, a terminal of the core wire  21  is stacked on an end  32   a  by the core wire movement part  33  of the core wire weld part  32 . 
     The core wire movement part  33  allows the terminal of the core wire  21  stacked on the end  32   a  by the core wire movement part  33  of the core wire weld part  32  to move (protrude) to an end by the electrical contact part  31  of the core wire movement part  33  in the case of mutually welding the core wire  21  to the core wire weld part  32  by applying ultrasonic vibration in a state of pressurizing the core wire  21  and the core wire weld part  32  in a direction of approaching each other. 
     The ultrasonic welding apparatus  1  mutually welds the core wire  21  to the terminal clamp  3  by applying ultrasonic vibration in a state of stacking the core wire  21  on the core wire weld part  32  and pressurizing the core wire  21  and the core wire weld part  32  in the direction of approaching each other. The ultrasonic welding apparatus  1  includes an apparatus body (not shown) installed on a floor etc. of a factory, an anvil (not shown) fixed to the apparatus body, a chip (also called a tool chip)  7  disposed in a position opposed to the anvil, a press jig (not shown), a voltage vibrator (not shown) as a driving source, a core wire protrusion prevention wall  5 , and a control circuit (not shown) as control means as shown in  FIGS. 1 and 2 . 
     The anvil is disposed in a position opposed to the chip  7  described below along a vertical direction, and pinches the core wire  21  and the terminal clamp  3  between the chip  7  and the anvil. Also, an end face whose anvil is mutually opposed to the chip  7  is formed in a flat shape along a direction orthogonal to a direction in which the anvil is mutually opposed to the chip  7 . Then, the end face of the anvil is equipped with the core wire weld part  32  (that is, the terminal clamp  3 ) on which the core wire  21  is stacked, and the core wire protrusion prevention wall  5  for preventing the terminal of the core wire  21  from moving to a place overlapping with the electrical contact part  31  is positioned in the end by the core wire movement part  33  of the electrical contact part  31  of this terminal clamp  3 . 
     The chip  7  is attached to a press jig described below and the chip  7  moves slidably along the vertical direction by this press jig. 
     The press jig includes, for example, a piston of an oil hydraulic cylinder. The press jig is attached to the apparatus body. Since the chip  7  is disposed slidably along the vertical direction by this press jig, the chip  7  can mutually be connected to and disconnected from the anvil when a force is applied from the press jig. 
     A piezoelectric vibrator is applied by a power source (not shown) etc. and vibrates (ultrasonically vibrates) at, for example, frequencies from 10 kHz to 80 kHz. The piezoelectric vibrator is attached to only the chip  7 . This piezoelectric vibrator vibrates (ultrasonically vibrates) the chip  7  by a vibrator (not shown). That is, the piezoelectric vibrator applies ultrasonic vibration to the chip  7 . In addition, the ultrasonic vibration refers to vibration obtained by applying a voltage to the piezoelectric vibrator and, for example, vibrating this piezoelectric vibrator and converting electrical energy into mechanical vibration. 
     The core wire protrusion prevention wall  5  is formed in a plate shape. The core wire protrusion prevention wall  5  is disposed along a direction orthogonal to the end face whose anvil is mutually opposed to the chip  7 , and is fixed to the apparatus body. Also, the core wire protrusion prevention wall  5  is positioned in the end by the core wire movement part  33  of the electrical contact part  31 , so that the core wire protrusion prevention wall  5  is disposed in a position close to the terminal of the core wire  21  when the terminal of the core wire  21  is stacked on the end  32   a  by the core wire movement part  33  of the core wire weld part  32  and also the core wire  21  is stacked on the bottom wall part  34  of the terminal clamp  3  with which the end face of the anvil is equipped and the core wire  21  is positioned between the pair of erect wall parts  35 . The core wire protrusion prevention wall  5  prevents the terminal of the core wire  21  stacked on the end  32   a  from moving (protruding) to the place overlapping with the electrical contact part  31  in the case of applying the ultrasonic vibration in a state of pinching the core wire  21  and the terminal clamp  3  between the anvil and the chip  7  and pressurizing the core wire  21  and the terminal clamp  3  in a direction of approaching each other. 
     The control circuit performs control of the whole ultrasonic welding apparatus  1  by connecting the piezoelectric vibrator to the press jig and controlling these operations. 
     Next, the ultrasonic welding apparatus  1  of the configuration described above welds the terminal clamp  3  to the core wire  21  of the electric wire  2  as described below. First, the anvil of the ultrasonic welding apparatus  1  is mutually moved away from the chip  7  and the end face of the anvil is equipped with the terminal clamp  3  so as to arrange the terminal clamp  3  in a position in which the core wire protrusion prevention wall  5  is positioned in the end by the core wire movement part  33  of the electrical contact part  31  of this terminal clamp  3 . Next, the terminal of the core wire  21  exposed by peeling the coat part  22  of the terminal of this electric wire  2  is stacked on the end  32   a  by the core wire movement part  33  of the core wire weld part  32  and the core wire  21  is stacked on the bottom wall part  34  of the terminal clamp  3  with which the end face of the anvil is equipped and the core wire  21  is positioned between the pair of erect wall parts  35 . Then, the press jig is moved from the upper portion of the vertical direction toward the lower portion and the chip  7  fixed to the press jig is inserted between the pair of erect wall parts  35  and the piezoelectric vibrator is vibrated in a state of being pressurized in a direction of moving the chip  7  toward the anvil and this vibration is applied to the core wire  21  and the terminal clamp  3  through the chip  7 . When the core wire  21  and the terminal clamp  3  are pinched between the anvil and the chip  7  and ultrasonic vibration is applied thus, the terminal clamp  3  and the core wire  21  made of metal mutually overlap and are contacted, so that a metal bond between the terminal clamp  3  and the core wire  21  mutually overlapping is performed mutually gradually in a solid phase in a state of no melt. In this case, (a portion of) the terminal of the core wire  21  to which the ultrasonic vibration is applied moves from the end  32   a  by the core wire movement part  33  of the core wire weld part  32  and makes close contact with the core wire protrusion prevention wall  5 . Thus, the core wire  21  and the terminal clamp  3  are mutually welded by the so-called ultrasonic welding (also called ultrasonic welding). That is, the electric wire  2  is electrically connected to the terminal clamp  3 . 
     When the control circuit pressurizes the core wire  21  and the terminal clamp  3  in the direction of approaching each other by the chip  7  attached to the press jig at a predetermined applied pressure and detects that the piezoelectric vibrator is vibrated for a predetermined time, vibration of the piezoelectric vibrator is stopped. Thereafter, the control circuit moves the press jig upward, and moves the chip  7  attached to the press jig away from the anvil. The core wire  21  and the terminal clamp  3  mutually welded are taken out of the end face of the anvil after the chip  7  is moved sufficiently away from the anvil thus. 
     According to the invention described above, the ultrasonic welding apparatus  1  includes the core wire protrusion prevention wall  5  which is disposed in the position close to the terminal of the core wire  21  and prevents the terminal of the core wire  21  from moving to the place overlapping with the electrical contact part  31 , so that in the case of applying ultrasonic vibration in a state of pinching the core wire  21  and the core wire weld part  32  between the anvil and the chip  7  and pressurizing the core wire  21  and the core wire weld part  32  in the direction of approaching each other, a portion of the terminal of the core wire  21  is welded to the terminal clamp  3  without moving (protruding) to the place overlapping with the electrical contact part  31 , with the result that an operator can screw a nut through a bolt after the connection terminal of the electronic device is stacked on the connection hole  31   a  of the terminal clamp  3  in the case of connecting the electronic device to the terminal clamp  3 , so that the ultrasonic welding apparatus  1  for manufacturing the wire harness  10  for improving attachment workability in the case of being attached to the electronic device can be provided. 
     Also, a portion of the terminal of the core wire  21  is attached to the electronic device in a state of being welded to the terminal clamp  3  without moving (protruding) to the place overlapping with the electrical contact part  31 , so that the ultrasonic welding apparatus  1  for manufacturing the wire harness  10  for preventing spoilage of beauty can be provided. 
     In addition, the embodiment described above only shows a typical form of the invention, and the invention is not limited to the embodiment. That is, various modifications can be made without departing from the gist of the invention.