Method of control and apparatus for hot-wire welding

• Main Authors: SADAKANE, MASAHIKO, KAWANO, SHIGEYOSHI, HORI, KATSUYOSHI, MYOGA, TOSHIHARU, TAKUWA, TOSHIAKI
• Format: Patent
• Language: English; French; German
• Published: 03.08.1994
• Edition: 5
• Subjects: CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR; PERFORMING OPERATIONS; SOLDERING OR UNSOLDERING; TRANSPORTING; WELDING; WORKING BY LASER BEAM

A method and an apparatus for controlling the hot-wire welding process is disclosed in which the heating power for a hot-wire is automatically regulated to a proper value. The wire-heating power after fusing of a filler wire (6) by being overheated is set to a level lower than the heating power immediately before wire fusing, and the wire-heating power is again increased gradually from the set value until the wire (6) is fused by being overheated. By repeating this process, the molten state of the filler wire (6) in the hot-wire TIG welding is automatically kept in optimum condition without requiring any operation of the welding operator or his intuition. Further, during the energization of the filler wire (6), the instant of fusing by overheating of the wire (6) is detected, and the detected signal is used to sharply reduce or suspend the wire current immediately, whereby spatters which otherwise might be caused by fusing of the overheated wire is prevented or greatly reduced, and the adhesion of the spatters to the arc electrode (2) is prevented, thereby permitting a hot-wire welding operation continuously over a long time. Furthermore, a pulsed current is used for heating the filler wire (6), and the wire terminal voltage during de-energization of the wire is detected, thereby detecting whether the wire (6) is in contact with a base metal (3). If the wire (6) is not in contact with the base metal (3), a current is not supplied during the next pulse application period, so that the current is prevented from flowing from a tungsten electrode (2) to the wire (6) while the wire (6) is not in contact with the base metal (3).