Spot welding machine
First Claim
1. A spot welding machine including a first electrode having a proximal end and a workpiece engaging end, and a second electrode opposed to said first electrode and having a proximal end and a distal end with a workpiece engaging face, whereby a workpiece is subjected to electric-resistance welding in a manner such that said workpiece is held between said first and second electrodes, comprising:
- a third electrode interposed between said first electrode and said workpiece, and having a proximal end, one distal-end side face abutting closely against said workpiece engaging end of said first electrode, and another distal-end side face in contact with said workpiece; and
AC power source means having a first terminal connected electrically with said proximal end of said first electrode, and a second terminal connected electrically with said respective proximal ends of said second and third electrodes, so that an AC current is supplied to said first and second terminals for a predetermined period,said AC power source means being adapted, during said predetermined period, to supply a current, used to heat said third electrode, to a closed circuit having a route comprising said first terminal, said first electrode, said third electrode, and said second terminal, and to supply a current, used to weld said workpiece as well as to heat said third electrode, to a closed circuit having a route essentially consisting of said first terminal, said first electrode, said third electrode, said workpiece, said second electrode, and said second terminal.
2 Assignments
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Accused Products
Abstract
A spot welding machine comprising a first electrode and a second electrode opposed to the first electrode, whereby a workpiece, including, e.g., a conductor wire coated with a heat-resistant resin film and a terminal to be welded to the conductor wire, is subjected to electric-resistance welding in a manner such that the workpiece is held between the first and second electrodes. In the spot welding machine according to the present invention, a third electrode is interposed between the first electrode and the workpiece so that one distal-end side face of the third electrode abuts closely against a workpiece engaging end of the first electrode, and that the other distal-end side face of the third electrode is in contact with the workpiece. The proximal end of the first electrode is connected to a first terminal of AC power source means, and the respective proximal ends of the second and third electrodes are connected to a second terminal. The AC power source means supplies a current, used to heat the third electrode and remove the resin coating film by fusion, to a closed circuit having a route essentially consisting of the first terminal, first electrode, third electrode, and second terminal, during a predetermined period. After the removal of the coating film, the AC power source means supplies a current, used to weld the workpiece, to a closed circuit having a route essentially consisting of the first terminal, first electrode, third electrode, workpiece, second electrode, and second terminal.
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Citations
11 Claims
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1. A spot welding machine including a first electrode having a proximal end and a workpiece engaging end, and a second electrode opposed to said first electrode and having a proximal end and a distal end with a workpiece engaging face, whereby a workpiece is subjected to electric-resistance welding in a manner such that said workpiece is held between said first and second electrodes, comprising:
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a third electrode interposed between said first electrode and said workpiece, and having a proximal end, one distal-end side face abutting closely against said workpiece engaging end of said first electrode, and another distal-end side face in contact with said workpiece; and AC power source means having a first terminal connected electrically with said proximal end of said first electrode, and a second terminal connected electrically with said respective proximal ends of said second and third electrodes, so that an AC current is supplied to said first and second terminals for a predetermined period, said AC power source means being adapted, during said predetermined period, to supply a current, used to heat said third electrode, to a closed circuit having a route comprising said first terminal, said first electrode, said third electrode, and said second terminal, and to supply a current, used to weld said workpiece as well as to heat said third electrode, to a closed circuit having a route essentially consisting of said first terminal, said first electrode, said third electrode, said workpiece, said second electrode, and said second terminal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification