Drive system for prosthetic fasteners

• US 5,019,080 A
• Filed: 02/13/1990
• Issued: 05/28/1991
• Est. Priority Date: 02/13/1990
• Status: Expired due to Fees

• Current Assignee: Camcar Division of Textron, Inc.
• Original Assignee: Trextron Incorporated
• Inventors: Hemer, H. Michael
• Primary Examiner(s): Pellegrino, Stephen C.
• Assistant Examiner(s): Jackson, Gary
• Application Number:
  US07/479,514
• Time in Patent Office: 469 Days
• Field of Search: 606/72-74, 606/104, 411/402-405, 411/408, 411/410, 411/395, 411/919
• US Class Current: 606/104
• CPC Class Codes: A61B 17/8615 at the central region of the screw head
• CPC Class Codes: A61B 17/888 the driver bit acting on the central region of the screw head
• CPC Class Codes: B25B 15/005 with cross- or star-shaped cross-section
• CPC Class Codes: F16B 23/003 star-shaped or multi-lobular, e.g. Torx-type, twelve-point star

Abstract

A fastener and fastener driver system for prosthetic devices and other more common type usages. The fastener is threaded with a driver engaging socket formed in the fastener head. The driver imparts rotational torque to the fastener and includes a drive bit portion engagable with the driver engaging socket formed in the fastener. The driver engaging socket and drive bit are formed with cooperative hexalobular surfaces the sides of which are generally parallel for releasably retaining the fastener on the driver. Each convex curved surface of the hexalobular surface formed on the end of the driver bit is downwardly inwardly beveled. Three alternating concave curved surfaces in the socket are formed with cooperatively mating beveled surface portions. When the driver is engaged with a fastener the beveled surface portions of the socket are triangularly engaged by the driver to securely releasably retain the fastener on the driver to prevent wobbling of the fastener when driven by the driver.

Claims

1. A threaded fastener with tool engaging means on a threaded shank adapted for use with a drive tool, said tool engaging means comprising:

a recessed socket formed in an end of said shank for receiving a drive tool, said recessed socket having a top edge and a bottom edge;

a central axis extending longitudinally through the fastener;

alternating concave and convex partially-cylindrical surfaces formed inside said recessed socket, the axes of curvature of said partially-cylindrical surfaces being generally parallel to each other and to said central axis, said recessed socket formed with at least three concave partially-cylindrical surfaces;

beveled surface portions formed on three of said concave surfaces sloping towards the central axis from the top edge of the recess to the bottom edge thereof, and said three concave surfaces being disposed generally at the apices of an equilateral triangle, said beveled portions formed for releasably engaging mating beveled surfaces formed on complementarily formed convex surfaces on said drive tool.

2. A threaded fastener with tool engaging means on a threaded shank adapted for use with a drive tool, said tool engaging means comprising:

an end surface formed on an end of said fastener;

a recessed socket formed in said end surface for receiving a drive tool, said recessed socket having a top edge and a bottom edge;

a central axis extending through said fastener;

alternating merging concave and convex curved partially-cylindrical surfaces formed inside said recessed socket, the axes of curvature of said partially-cylindrical surfaces being generally parallel to each other and to said central axis, said recessed socket formed with six concave partially-cylindrical surfaces;

beveled surface portions formed on said concave partially-cylindrical surfaces sloping towards the central axis from the tope edge of the recess to the bottom edge thereof for releasably engaging complementarily beveled surface portions formed on said drive tool, said beveled surface portions formed on at least three alternately spaced concave partially-cylindrical surfaces such that each beveled surface portion neighbors at least one non-beveled concave partially-cylindrical surface.

3. A threaded fastener as in claim 2 wherein said beveled surfaces taper from a top edge of said recessed socket downwardly towards the bottom of said recessed socket.

4. A threaded fastener as in claim 2 wherein said beveled surface portions are sloped downwardly at an angle of less than 5°

.

5. A threaded fastener as in claim 3 wherein said beveled surface portions taper downwardly inwardly toward said central axis at an angle of approximately 3.5°

.

6. A threaded fastener with tool engaging means on a threaded shank adapted for use with a drive tool, said tool engaging means comprising:

an end surface formed on an end of said fastener;

a recessed socket formed in said end surface for receiving a drive tool, said recessed socket having a top edge and a bottom edge;

a central axis extending longitudinally through the fastener;

alternating merging concave and convex partially-cylindrical surfaces formed inside said recessed socket, the axes of curvature of said partially-cylindrical surfaces being generally parallel to each other and to said central axis, said recessed socket formed with at least five concave partially-cylindrical surfaces;

beveled surface portions formed on at least three concave partially-cylindrical surfaces in said recessed socket of which at most two of said beveled surfaces are formed on neighboring concave partially-cylindrical surfaces, said beveled surface portions slope towards the central axis from the top edge of the recess to the bottom edge thereof for releasably engaging complementarily beveled surface portions formed on mating convex partially-cylindrical surfaces formed on said drive tool;

said complementarily beveled surface portions being sloped inwardly towards said central axis.

7. A fastener and driver combination comprising:

a threaded fastener with an end surface formed on an end of said fastener, engagement means formed on said end surface for receiving said driver, said recessed socket having a top edge and a bottom edge, a central axis extending longitudinally through said fastener;

a driver for imparting rotational torque to said fastener and including a drive bit portion engagable with said engagement means, a bit axis extending longitudinally through said bit;

alternating merging concave and convex partially-cylindrical surfaces formed on an outside surface of one of said engagement means and said bit, mating partially-cylindrical surfaces formed on an inside surface on the other of said engagement means and said bit, the axes of curvature of said partially-cylindrical surfaces being generally parallel to each other and to said central axis and said bit axis for releasably retaining said fastener on said driver, at least five convex partially-cylindrical surfaces formed on said outside surface and matingly engagable concave partially-cylindrical surfaces formed on said inside surface;

beveled surface portions being formed on said concave partially-cylindrical surfaces of said inside surface, said beveled surface portions sloping inwardly towards said central axis at an angle from the top edge of the recess to the bottom edge thereof, said beveled surface portions being formed on at least three concave partially-cylindrical surfaces of which at most two of said beveled surface portions are formed on neighboring concave partially-cylindrical surfaces, correspondingly beveled surface portions formed on said outside surface on each convex partially-cylindrical surface.

8. A threaded fastener and driver combination, said fastener being formed with tool engaging means on a threaded shank for engagement with said driver, said tool engaging means comprising a recessed socket formed in an end of said shank for receiving a cooperatively formed portion of said driver, said recessed socket having a top edge and a bottom edge;

a central axis extending longitudinally through the fastener;

alternating concave and convex partially-cylindrical surfaces formed inside said recessed socket, the axes of curvature of said partially-cylindrical surfaces being generally parallel to each other and to said central axis, said recessed socket formed with at least three concave partially-cylindrical surfaces;

beveled surface portions sloping towards the central axis from the top edge of the recess towards the bottom edge thereof and are formed on three of said concave surfaces being disposed generally at the apices of an equilateral triangle;

said driver being formed for imparting a rotational torque to said fastener when engaged therewith and including a bit portion formed with alternating concave and convex partially-cylindrical surfaces for complementary engagement with said alternating concave and convex partially-cylindrical surfaces formed inside said recessed socket, complementary beveled surface portions formed on each of said convex surfaces of said bit portion for complementary engagement with said beveled surface portions formed on three of said concave surfaces formed in said recessed socket, when said driver is engaged with said fastener, said beveled surfaces formed on said convex partially-cylindrical surfaces releasably engaging said beveled surface portions formed on three of said concave surfaces formed inside said recessed socket.

9. A fastener and driver combination comprising:

a threaded fastener with engagement means formed on said end surface for receiving said driver, a central axis extending longitudinally through said fastener;

a driver for imparting rotational torque to said fastener and including a drive bit engagable with said engagement means, a bit axis extending longitudinally through said bit and being coaxial with said central axis when said bit is engaged with said engagement means;

alternating merging concave and convex partially-cylindrical surfaces formed on an outside surface of one of said engagement means and said bit, corresponding partially-cylindrical surfaces formed on an inside surface on the other of said engagement means and bit, said inside surface being defined by a top edge and a bottom edge thereof, axes of curvature of said partially-cylindrical surfaces being generally parallel each other and with said central axis and said bit axis for releasably retaining said fastener on said driver, at least six convex partially-cylindrical surfaces formed on said outside surface and matably formed concave partially-cylindrical surfaces formed on said inside surface;

first beveled surface portions formed at the apices of a triangle formed between three of said partially-cylindrical surfaces formed on said inside surface, said first beveled surface portions being sloped inwardly towards said central axis from said top edge towards said bottom edge, second beveled surface portions cooperatively formed on each of said convex surfaces formed on said outside surface for engagement with said first beveled surface, when said bit is releasably inserted into said engagement means said bit is triangularly releasably engaged in said engagement means to prevent said fastener from wobbling when driven by said driver.

10. A threaded fastener as in claim 9 wherein said beveled surface portions taper inwardly toward said central axis at an angle of approximately 3.5°

.

11. A fastener and driver combination according to claim 9 wherein said bit axis and said central axis are coincident.

12. A fastener and driver combination comprising:

a threaded fastener with a recessed socket formed in an end surface thereof for receiving said driver, a central axis extending longitudinally through said fastener, alternating merging concave and convex partially-cylindrical surfaces formed inside said recessed socket, the axes of curvature of said partially-cylindrical surfaces being generally parallel each other and with said central axis, said recessed socket being formed with six concave partially-cylindrical surfaces;

a driver for imparting rotational torque to said fastener and including a drive bit, a bit axis extending longitudinally through said bit, alternating merging concave and convex partially-cylindrical surfaces formed on an outside surface of said bit cooperatively formed to engage said partially-cylindrical surfaces formed inside said recessed socket;

first beveled surface portions formed on three alternately spaced concave partially-cylindrical surfaces formed in said recessed socket, said first beveled surface portions sloped inwardly towards said central axis, cooperatively formed second bevel portions surfaces formed on each of the convex partially-cylindrical surfaces of said bit for engaging said first beveled surface portions when said bit is engaged with said recessed socket.