Contact Clamp for Graphite Electrodes

This invention relates to a contact clamp for graphite electrodes which is used during the process of applying a protective coating onto the electrodes.

An arrangement for this purpose is known in which in the nipple seat of the graphite electrode there are screwed-on journals, which represent a semi-nipple with a central hole bored in it. The journal is slipped over a metal rod, in both ends of which there are welded strips with seats for set bolts. In the one end of the metal rod there is shaped a seat for a center.

The drawbacks of this arrangement are: it is an expensive device of heavy weight, which requires frequent replacement and maintenance of the worn-out elements; the attachment of the equipment to the electrodes requires heavy physical labor. Moreover, it cannot provide a precise coaxial alignment between the journal and the electrode; this results in an excentricity which impairs the quality of the coating. The current passing through the journal encounters many transition resistances which produce varying drops of the voltage.

It is, therefore, a general object of the present invention to avoid the aforementioned drawbacks by providing a contact clamp for graphite electrodes, which is used during the process of applying a protective coating thereon, this clamp being easy to maintain and to install and providing a current supply over the shortest path with the least possible transient resistances.

This object is achieved by means of a contact clamp for graphite electrodes comprising a shaft, the one end of which is shaped as a cone, while the other ends with a neck over which a metal hub, shaped as a truncated cone, is slipped. Fastened to the shaft is a current carrying disk, which is in contact with current-supplying brushes. The current carrying disk is connected to the shaft by means of lugs, seated in apertures formed in its base, the lugs being pressed in a flange formed on the shaft, while the current-carrying disk touches the face of the graphite electrode. Over the metal hub there is slipped a conical sleeve.

For a better understanding of the invention, reference is made to the accompanying drawings, in which:

FIG. 1 is a sectional view through a nipple seat and the contact clamp, in which the current-carrying disk is press fitted on the shaft;

FIG. 2 is a sectional view of another embodiment in which the current-carrying disk is attached to the shaft by means of lugs;

FIG. 3 is a plan view of a current-carrying disk; and

FIG. 4 is a sectional view of another embodiment in which a conical sleeve is slipped over the metal hub.

In the centering seat 7 of the body of the coating machine there is disposed the cone-shaped end 2' of shaft 2, the other end of which is formed with a neck 2", over which there is slipped a metal hub 1, disposed in the nipple seat 4' of the graphite electrode 4. Fastened to shaft 2 is the current-carrying disk 5, which is in contact with current-supplying brushes 6.

In another embodiment the current-carrying disk 5 is connected to shaft 2 by means of lugs 3, which are pressed in flange 8 formed on shaft 2. The current-carrying disk 5 touches the face of the graphite electrode 4. A conical sleeve 9 is slipped over the metal hub 1.

The operation of the contact clamp is as follows: after transfering the graphite electrode 4 to the coating machine, the metal hub 1 comes into the nipple seat and centers the electrode 4 until the current-carrying disk 5 is pressed against the face of electrode 4. The current supply is effected by means of current-supplying brushes 6 through the current-carrying disk 5 towards the rotating electrode.