PURPOSE: To prevent sparking and to improve quality of W wires by using the fine W wires tightened like sponge for the parts of electrodes for electrical heat treatment which anneal the traveling W wire by conducting electric current thereto contact the W wire.
CONSTITUTION: A W (tungsten) wire 1 to be annealed is fed continuously by a coiler and is passed between a pair of electrode 3 and 4 provided in a furnace 2. The electrode 3 is fixed but the electrode 4 is held energized by a spring 5; therefore the electrodes 3, 4 contact the wire 1 satisfactorily. In this case, the parts of the electrodes 3, 4 which sre in contact with the wire 1 are formed of the W wires of ≤25μ sizes which are tightened like sponge. If a voltage is applied between the electrodes 3 and 4, the wire 1 evolves heat of itself and is annealed. The parts of the electrodes in contact with the wire 1 do not consume early, and since no sparking is generated, the wire 1 is heat-treated uniformly to high quality.
YAMADA YASUHIKO
YOSHIDA TAKESHI
