Traversing core rod detecting device

In injection blow molding apparatus having an indexing head with angularly related faces from which a plurality of core rods extend at locations spaced across the width of each face, an injection station, a blowing station, and a pick-off station at angularly spaced locations around the indexing head, and means for rotating the indexing head intermittently about a center to successively bring each face, and the core rods that extend therefrom, into position to cooperate with each of the stations, the combination comprising a carriage, a track extending lengthwise parallel to the extent of the face of the indexing head which is at rest at the pick-off station, the carriage being on said track and moveble lengthwise thereof, motor-operated motion-transmitting means that propel the carriage along the track following discharge of molded parts from the core rods at the pick-off station and only while the indexing head is stationary and prior to delivery of the rods to the injection station, a residue detector connected to and movable with the carriage transversely of the length of the core rods and extending into positions to strike against residue on each core rod while the indexing head remains at rest, if there is any residue on any of the core rods after blown objects have been stripped therefrom at the pick-off station, and a controller responsive to the striking of residue on any core rod by the detector during a traverse of the carriage across the stationary locations of the successive core rods at the pick-off station.