Tool holder for drilling machines, drilling device as well as drills and set of drills

A tool holder for drilling machines which has at least two jaws for the chucking of drill-chucking shanks of different thickness, wherein a jaw holder has a hollow space to receive chucking shanks to be chucked and wherein the jaws are radially adjustable and lockable in the jaw holder for selective engagement with an inserted chucking shank, characterized in that the hollow space is cylindrical and defines a supporting guide bore for reception of chucking shanks of maximum diameter conforming to the bore diameter, that each of the jaws has a drill-bit engageable front surface which is cylindrically arcuate and which substantially conforms to the geometric cylinder of said space in the retracted position of the jaws, and said front surface of each jaw is interrupted by a longitudinal rib formation which in the retracted position of the jaws intrudes only partially into the geometric cylinder of said space.

A drilling device comprising a tool holder with a jaw holder having a hollow space to receive a chucking shank to be chucked, and a drill bit having a chucking shank receivable in the hollow space, wherein plural jaws are radially adjustable and lockable in the jaw holder for selective releasable engagement with the chucking shank, characterized in that the hollow space is cylindrical and the chucking shank has a cylindrical circumferential surface so conforming to the geometric cylinder of said hollow space that the hollow space forms an axial guide for the chucking shank, that each of the jaws has a radially inwardly extending longitudinal drill-bit engageable rib formation, and that the chucking shank is characterized by chucking grooves configured for angularly locating axially inserted reception of the chucking shank.

A drill bit for selective retention by the multiple-jaw chuck of a portable rotary drill, said drill bit having a chucking shank which has at least two angularly spaced longitudinal chucking grooves having bottom surfaces which are cylindrically arcuate about the axis of the drill bit, the central region of each groove bottom being characterized by a longitudinal trough.

A drill bit for selective retention by the multiple-jaw chuck of a portable rotary drill, said drill bit having a cylindrical chucking shank which has at least two angularly spaced longitudinal chucking grooves, said grooves having bottom surfaces which are convex and cylindrically arcuate to equal radii and about their respective axes, said respective axes being parallel to and equally offset from the drill-bit axis, and said equal radii being equal to or greater than the cylindrical radius of the chucking shank.

A drill bit for selective retention by the multiple-jaw chuck of a portable rotary drill, said drill bit having at one end a chucking shank which has at least two axially extending chucking grooves for keyed engagement to the chuck jaws, characterized in that at least one chucking groove terminates at a chucking-groove end which is short of said drill-bit end, and said chucking-groove end communicates directly with said drill-bit end via an introduction groove of smaller section area than that of the chucking groove, and the introduction groove being narrower than the chucking groove, whereby the terminated end of the chucking groove provides a sure abutment for an engaged chuck jaw.

A set of drill bits having chucking shanks of different thicknesses wherein at least one thicker chucking shank has at least two axially extending chucking grooves for keyable engagement to separate jaws of a chuck, and wherein at least one thinner chucking shank has at least two axially extending jaw-engageable surfaces which are not concentric to the axis of said thinner chucking shank.