Method and apparatus for joining new electrode to consumed electrode of electric furnace

A method for joining a new electrode to a consumed electrode vertically disposed in an electric furnace comprising the steps of:

• lifting and transporting the new electrode by a carrier means to a position above the consumed electrode in the electric furnace;
• and
• rotating the new electrode about an axis thereof and joining the new electrode to the consumed electrode by screw means on ends of said electrodes;
• said method including suspending said new electrode from said carrier means by a joining apparatus which is provided with an electric motor for rotating the new electrode about said axis, said electric motor of the joining apparatus being operable such that stalling torque of the electric motor corresponds to a predetermined tightening torque, setting said stalling torque by controlling strength and frequency of an electric current flowing in the electric motor and tightening said new electrode to the consumed electrode at the predetermined tightening torque applied by the electric motor in a stalling state;
• wherein said electrodes are aligned with each other by aligning means comprised of a projector means emitting a light beam and a positioning marker, said aligning means being associated with the carrier means and a stationary member mounted adjacent to the consumed electrode whereby said electrodes are aligned by aligning a light beam from the projector means with respect to the positioning marker.