Band overlap detector switch for continuous ribbon mandrel

Claim 1

A band overlap detecting apparatus for a continuous ribbon mandrel having an endless forming surface provided by a continuously helically advanceable band helically wound in a plurality of side-by-side convolutions and having electric driving means for the band, comprising a first elongated member having a first end portion in operative engagement with a first one of the convolutions and an opposite second end portion mounted to accommodate pivotal movement of the member about an axis generally parallel to the axis of the helix defined by the helically wound band, a second elongated member spaced from the first member axially of the helix and extending generally parallel to the first member, the second member having a first end portion in operative engagement with a second one of the convolutions immediately preceding the first one operatively engaged by the first member, means mounting the second member on the first member at intermediate portions respectively theReof for pivotal movement of the second member with respect to the first member about an axis generally parallel to the axis of the helix, electric switch means mounted on one of the members and disposed between the mounted second end portion of the first member and the axis of pivotal movement of the second member with respect to the first member, the switch means having a pair of normally open contacts and a depressible actuator closing the contacts when depressed to complete a circuit through the electric driving means for the band, actuator depressing means mounted on the other of the members and engageable with the actuator of the switch means, and biasing means operatively connected to a second end portion of the second member and urging the actuator depressing means and the actuator toward each other to maintain the contacts of the switch means closed during normal operation of the mandrel, the biasing means also urging the first end portion of the second member rotatably about the axis of pivotal movement of the second member and toward the second convolution, whereby upon undesired overlapping of the first convolution by the second convolution, the second member is pivoted against the force of the biasing means to release the actuator and permit the contacts of the switch means to open and interrupt the circuit through the driving means for the band.