Retractable knife for skiving tool

A retractable knife for use in rotary skiving operations comprising:

• a pair of knife means extending in opposite directions from the axis of rotation each including knife blade holders slideable relative to one another, one said knife plate holder including a guide slot parallel to the axis of rotation and defining camming surfaces parallel to said axis, the other knife blade holder including a transverse recess perpendicular to the axis of rotation;
• a guide dart located in said transverse recess and having camming surfaces confronting those of the guide slot, the camming surfaces of the guide dart including a first portion inclined at an acute angle to the axis of rotation and a second portion parallel to the axis of rotation;
• means for adjusting the radial position of the guide dart;
• a push dart having camming surfaces engageable with the camming surfaces of the guide slot and the guide dart, said push dart being movable from a first position in engagement with the guide slot and the inclined first portion of the camming surfaces of the guide dart and a second position in engagement with the guide slot and the parallel camming surfaces of the guide dart;
• means for moving the push dart from the first position to the second position, movement of the push dart from the first position to an intermediate position causing the holders to slide radially outwardly relative to one another and movement of the push dart from the intermediate position to the second position locking the holders in place relative to one another in their outwardly extended configuration;
• and
• means for returning the push dart from its second position to its first position including cam means to retract the knife blade holders.