A drive system with full surface drive contact. The drive system tends to maximize the surface contact pattern or area at typical bit-recess reaction (drive) torque values, thereby tending to minimize bit-recess surface contact stresses, coating damage, recess ream and premature bit fatigue failure. The drive system comprises a fastener and/or bit having drive surfaces formed of either polygon involutes or a single arc construction. A punch is also provided for forming a recess in either the fastener or the bit, wherein the punch has corresponding surfaces.

A driver for applying torque to threaded fasteners has a plurality of teeth extending along and projecting outwardly from a longitudinal axis of a body on which the teeth are located. The teeth have a helical twist about the longitudinal axis. Each tooth has an angularly oriented engagement surface which is engageable with similarly angularly oriented surfaces within recesses in the head of a compatible fastener. When the driver engages the recesses torque applied to the driver draws the driver deeper into the recesses as the engagement surfaces react against and slide over the angularly oriented surfaces within the recesses. The torque also causes the fastener to turn and advance or retract depending upon the sense of the torque and the angles of the engagement surfaces and the angles of the surfaces within the recesses. The fastener and its method of manufacture are also disclosed.

A drive system with full surface drive contact. The drive system tends to maximize the surface contact pattern or area at typical bit-recess reaction (drive) torque values, thereby tending to minimize bit-recess surface contact stresses, coating damage, recess ream and premature bit fatigue failure.

The invention provides a screw in which the screw head (1) has a slot (2) in the upper surface of the screw head, an upper peripheral wall (9) of regular planform extending down from the rim of the slot into the screwhead, the upper peripheral wall (9) being generally aligned with the axis of the screw to form a recess (3), a sloping transition surface (15), extending downwardly and inwardly with respect to the lower edge of the upper peripheral wall (9), and a further recess (11) extending downwardly from the lower edge of the sloping transition surface (15), in which the dimensions of the screw head are such that when the screwhead is engaged by a tool (6) having upper (16) and lower (17) engagement sections, and in which the upper engagement section (16) extends downwardly with respect to the axis of the screw to which the tool is to engage and the lower engagement section (17) extends further downwardly, and in which there is at least one protrusion (or rib) (21) on the inside wall (12) of the further recess (11), so that there is a stick fit between the protrusion (21) on the inside wall (12) of the further recess (11) and the lower engagement section (17) of the tool (6).

A drive system with full surface drive contact. The drive system tends to maximize the surface contact pattern or area at typical bit-recess reaction (drive) torque values, thereby tending to minimize bit-recess surface contact stresses, coating damage, recess ream and premature bit fatigue failure.

A method and an apparatus for manufacturing a stepped member are provided. An intermediate portion of a shaft workpiece is radially enlarged while being compressed in an axial direction by applying alternating load to the intermediate portion in a direction intersecting the axial direction in a state in which pressure that compresses the shaft workpiece in the axial direction is applied to both ends of the shaft workpiece. The enlarged intermediate portion of the shaft workpiece is cat in a direction perpendicular to the axial direction so that the shaft workpiece is divided into two stepped members. Each of the stepped members has a shaft portion and a head portion provided at an axial end of the shaft portion, and the head portion has a larger diameter than the shaft portion.

A method and an apparatus for manufacturing a stepped member are provided. An intermediate portion of a shaft workpiece is radially enlarged while being compressed in an axial direction by applying alternating load to the intermediate portion in a direction intersecting the axial direction in a state in which pressure that compresses the shaft workpiece in the axial direction is applied to both ends of the shaft workpiece. The enlarged intermediate portion of the shaft workpiece is cat in a direction perpendicular to the axial direction so that the shaft workpiece is divided into two stepped members. Each of the stepped members has a shaft portion and a head portion provided at an axial end of the shaft portion, and the head portion has a larger diameter than the shaft portion.

A mold, punch and workpiece are provided. In a preferred embodiment, a tapering outer edge is provided, along with a plurality of rib sets arranged circumferentially about the outer edge, and a ramp. A ramp may be located to facilitate the removal of burrs. Various slot patterns may be provided or formed, including star-shapes/Torx slots. Using the present invention, a driver bit may be more securely fit to the slot of a screw, for example, allowing the screw to be threaded into a machined part more securely and smoothly, reducing rocking, shaking or tilt.

A method of manufacturing a welding stud. The welding stud comprises a weldable portion of light metal and a functional portion of steel. The method comprises the steps of: providing a welding part of a light metal and partially defining a recess, providing a function part of a steel and which includes a protrusion, providing a press with a die and a punch, arranging the welding part on the die and the function part on the press such that the protrusion opposes the recess, and manufacturing the welding stud by impacting the welding part and the function part into the die by the punch such that the protrusion enters the recess and the welding portion forms a sleeve around an end of the function portion to form the welding stud with the welding part forming the weldable portion and the function part forming the functional portion.

A bolt includes a head portion on which a recess is formed. The recess has a bottom surface and a sidewall extending from a periphery of the bottom surface. The sidewall has a lower end defined by the bottom surface and includes an increased diameter portion and a reduced diameter portion. The increased diameter portion has an inner diameter larger than an inner diameter of the lower end of the side wall. The reduced diameter portion has an inner diameter smaller than the inner diameter of the increased diameter portion. The reduced diameter portion is located opposite to the bottom surface across the increased diameter portion.