Automatic screw feeding mechanism for an automatic screw driving device

Claim 1

An automatic screw feeding mechanism for an automatic screw driving device, said automatic screw driving device including a rotatable tool bit and a rotating means for axially rotating said tool bit, said automatic screw feeding mechanism comprising: a feed belt including an elongated strap formed with a plurality of spaced and aligned positioning rings, and a plurality of screws each having a shaft portion retained in one of said positioning rings, said strap having a longitudinal side provided with a plurality of spaced notches, each of said notches being disposed between two adjacent positioning rings; a hollow casing having a rear open end and a front open end; a connector plate mounted on said rear open end of said hollow casing, said connector plate having a central opening to releasably engage one end of said automatic screw driving device, said central opening serving as a passage for said tool bit; a guide member provided inside said casing, said guide member having a front end extending out of said front open end of said casing, said front end of said guide member being engagable against an operating surface, said casing being slidably mounted on said guide member, said guide member including a pair of spaced guide plates and a connecting rod joining said guide plates; an axial seat mounted between said guide plates and defining an axial opening aligned with said central opening of said connector plate, said axial seat having a ratchet wheel rotatably provided on one side thereof, said ratchet wheel having a periphery formed with a set of spaced ratchet teeth, said feed belt being provided between said guide plates in front of said axial seat, one of said ratchet teeth engaging one of said notches on said feed belt to align one of said screws with said axial opening of said axial seat; a first spring means connecting said axial seat and said connector plate, said first spring means being compressed when said casing is urged by said automatic screw driving device to move from an initial position to a second position, wherein said tool bit extends into said axial opening to rotatably drive an aligned one of said screws into the operating surface and release said aligned one of said screws from said strap during a screw driving operation; a hook means for rotating said ratchet wheel by a predetermined angular rotation when said first spring means expands to move said casing back to the initial position after the execution of a screw driving operation, said ratchet wheel being rotated by said hook means so that said ratchet wheel can engage a succeeding one of said notches on said feed belt in order to align a succeeding one of said screws with said axial opening; each of said guide plates being formed with a rail groove, said rail groove having a horizontal section and a downwardly curving section disposed on a front end of said horizontal section, said curving section having a curvature corresponding to that of said ratchet wheel; said hook means comprising a slide frame having a front roller pair movably provided in said curving section of said rail groove of said guide plates, a rear roller pair movably provided in said horizontal section of said rail groove of said guide plates, and a hooking post provided near a rear end of said slide frame; a second spring means connecting said slide frame and said connector plate; a hook member pivoted on a front end of said slide frame and having a pointed hook end extending into a toothed region of said ratchet wheel; a third spring means connecting one end of said hook member and said hooking post; and a pawl means associated with said ratchet wheel to arrest counterclockwise rotation of said ratchet wheel; said second spring means urging said slide frame to move along said rail groove of said guide plates when said casing moves from the initial position to the second position, said hook end of said hook member moving past a first one of said ratchet teeth of said ratchet wheel as said front roller pair reaches a terminating end of said curving section of said rail groove, the movement of said casing back to the initial position causing said second spring means to pull said slide frame rearward and prompt said hook member to contact said first one of said ratchet teeth and cause limited clockwise movement of said ratchet wheel.