Screwdriver with replaceable bit assembly

An apparatus for automatically power driving fasteners which are joined together in a strip comprising:

• housing means;
• power drive means secured to the housing means;
• drive shaft means operatively connected to the power drive means for rotation and defining a longitudinal axis;
• slide body means coupled to the housing for reciprocal displacement parallel to the axis of the drive shaft means;
• spring means biasing said body means forwardly relative to the housing means parallel the axis to the extended position;
• guide channel means for said fastener strip extending through said slide body means;
• the body means including guideway means to receive screws when advanced therein via the guide channel means and to locate the screws in alignment with said drive shaft means for engagement thereby in driving of the screws from the guide tube means by the drive shaft means on reciprocal displacement of the slide body means relative the housing means;
• the improvement wherein the drive shaft means comprises elongate mandrel means having at a forward end axially engaging socket means;
• bit means disposed in the socket means for rotation with the socket means with a forward screw engaging end of the bit means extending from the socket means;
• the bit means received in the socket means whereby the bit means may move in a substantially ball-and-socket manner relative the socket means from an orientation in which a longitudinal axis of the bit means is coaxial with the axis of the drive shaft means to orientations in which the axis of the bit means is inclined at an angle of at least 2.degree. relative the axis of the drive shaft means with the screw engaging end of the bit means displaced away from the axis of the drive shaft means to assist the screw engaging end of the bit means in driving engagement of a screw which is not coaxially aligned with the axis of the drive shaft means;
• the bit means includes a frustoconical stop surface disposed about the longitudinal axis of the bit, and the socket means includes a frustoconical stop surface disposed about the axis of the drive shaft means and complementary to the frustoconical stop surface of the bit for engagement therewith on the bit means being forced into the socket means whereby engagement between the frustoconical top surfaces biases the bit means toward axial alignment in the socket means.

A driver tool comprising either a screwdriver or a nut driver comprising a mandrel elongated along and rotatable about a longitudinal mandrel axis, the mandrel having at a forward end a socket extending from a socket opening at the forward end of the mandrel rearwardly along the mandrel axis, to a rearward end,

• a replaceable bit extending along a bit axis from a forward bit end to a rearward bit end, generally coaxially removably received in the socket,
• a resiliently deformable split-ring carried by one of the mandrel and the bit retaining the bit in the socket against a force less than a required force,
• the socket having a forward section polygonally shaped in cross-section, and an enlarged diameter portion spaced rearwardly from the forward section,
• the bit having a polygonal body portion polygonally shaped in cross-section complimentary to the polygonally shaped forward section of the socket, a rearward bit portion rearward of the polygonal body portion, and an inwardly extending annular groove thereabout intermediate the polygonal body portion and the rearward bit portion for engaging the spit-ring,
• wherein with the bit received in the socket, the split-ring biases to locate partially in the groove and partially engaging the expanded diameter portion to secure the bit in the socket with the rearward bit portion locating in the enlarged diameter portion, the polygonal body portion locating in the polygonally shaped forward section of the socket, and the forward end of the bit extending from the socket opening for engaging a fastener,
• the bit and socket sized to permit movement of the bit in the socket between a first orientation where the bit axis is aligned with the mandrel axis, and a plurality of second orientations where the bit axis is inclined at an angle of at least 2.degree. and not more than 10.degree. relative to the mandrel axis and further inclination of the bit axis relative to the mandrel axis is prevented by engagement between surfaces of the polygonal body portion and the forward section of the socket,
• wherein on rotation of the mandrel the forward section of the socket engaging the polygonal body portion to rotate the bit without the transfer of rotational forces or any substantial forces acting normal the mandrel axis from the socket to the bit rearward of the annular groove.