US 6,183,608 B2Granted

Electrode positioning mechanism

OwnerWilbur A. Dammann, W. David Wallmaninventors

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Abstract

The electrode positioning mechanism includes a reversible electric motor. The motor rotates a worm gear which drives a spur gear. The spur gear is connected to an internally threaded collar which is adapted to receive an externally threaded sleeve. The sleeve can move axially lengthwise with respect to the collar. The sleeve acts as a housing for the electrode. Means are provided to retain the sleeve within the collar such that mechanical movement is restricted. The restriction in mechanical movement causes the torque applied by the worm gear to increase. The worm gear is allowed to move axially along the length of the motor shaft. The worm gear is biased into a longitudinally central position by at least one spring. As torque increases, the worm gear is moved from its central position against the urging of the spring. The worm gear is also connected to a washer with a diameter greater than that of the worm gear. The washer moves with the worm gear and is in communication with a switching means that will reverse the direction of the motor when one washer is so moved.

Claims5

Dependent claims

An electrode positioning mechanism, comprising:

a reversible electric motor having a rotating drive shaft, said motor mounted on a support frame;
a worm gear mounted on a gear shaft for rotation therewith, the gear shaft connected to said drive shaft for rotation therewith;
said gear shaft mounted between a pair of supports on said frame for rotational movement on a rotational axis and axial slidable movement along the rotational axis;
biasing means interposed between the supports and the worm gear for biasing the worm gear to a central location between the supports;
a spur gear in operative engagement with said worm gear;
an internally threaded collar having an axis affixed to said spur gear;
an externally threaded sleeve coaxial with said internally threaded collar and having an axial opening therethrough and received by said internally threaded collar wherein rotation of said internally threaded collar about said axis causes the axial lengthwise movement of said externally threaded sleeve;
an electrode positioned in said opening in said externally threaded sleeve for movement therewith;
switching means connected to said reversible electric motor for reversing the direction of rotation of said drive shaft;
and
position sensing means mounted on said frame, for detecting axial movement of the worm gear and shaft in first and second directions along the gear shaft axis;
said position sensing means connected to said switching means to reverse the motor upon detection of movement of the gear shaft in the first or second directions.

9 more elements

Dependencies are inferred from the claim text.