Abstract: A recessed screw having in its head a recess for engaging with a driver bit, with the recess being defined with curved engaging walls and radial or corner grooves. Each engaging wall is a portion of a conical surface slanted inwardly towards a bottom of the recess. Each corner groove extends outwards from the adjacent engaging walls in radial direction. A pair of vertical side walls, lying parallel with the recessed screw's axis define each corner groove. The driver bit has protrusions tightly fittable in the recess, which recess may be a superimposition of two square holes disposed symmetrically with a phase shift of 45.degree. around the axis so as to provide eight corner grooves. Each engaging wall may be formed at a place where the side walls intersect one another. The driver bit may comprise a shank and a bit portion which extends from the shank and formed with eight V-shaped grooves extending axially of the bit so that eight blades are defined each between the two V-shaped grooves.

Abstract: A screw fastener and a tool for driving the screw fastener is disclosed. The screw fastener has a polygonal driving socket in its head, the driving socket having a substantially square first section and a second section including a rectangular slot radiating outwardly from the center of each side wall of the first section. The depth of the first and second sections are the same. Further, the screw fastener may be provided with internal ducts for conveying lubricant into a workpiece hole in which the fastener is being turned. A driving tool having a square shank for turning the screw fastener is also disclosed. One end of the tool's shank has a driving section comprising a rectangular fin extending longitudinally along and radiating outwardly from the center of each side wall of the shank. The shape of the driving section is complementary in shape to, and dimensioned to be snugly received in, the driving socket.

Abstract: By modifying a shape of a head part of a screw, an inserting performance when a punching operation is carried out, a fastening performance when the screw is seated, and a finishing process upon completion of fastening against a member to be fastened are improved.A seat surface of the head part is formed in an inverse truncated conical shape with its outer circumference being a curved concave surface and the upper surface of the head part is formed with a spherical concave surface. The head part is provided with a plurality of spot facing projections extending from the seat surface of the small diameter part at the lower portion of the head part adjacent to the screw shaft part along the curved concave surface of the seat surface in a longitudinal direction. The upper surface of the head part formed in the spherical concave surface is provided with chamfered portions in which an opening edge of the engaging groove of a cross-shaped hole is cut in a conical shape.

Abstract: A shape of the head part of the screw is improved and performance of insertion of the screw when punched and performance of fastening of the screw when seated as well as a finishing treatment upon completion of the fastening against a fastened member are improved.The head part is made such that the upper surface having an engaging groove to with which a screw driver tool is engaged has a spherical surface, and the head part is comprised of an upper large diameter part formed with a first seat surface of inverse truncated cone shape having an outer circumference of a curved concave surface and a small diameter part formed with a second seat surface of an inverse truncated cone shape concentrically and integrally connecteed to a lower part of the large diameter part and having its outer circumference of a curved concave surface, and an annular projecting edge is formed at a connection part between the seated surfaces of the two-stage curved concave surfaces.

Abstract: A recessed drive socket in a fastener or the like, is driven by a mating, drive tool received within the socket. The socket cavity has a multilobular cross-section defined by an alternating annular series of adjacent socket flutes and socket lobes extending parallel along a general central axis from an entrance opening into the cavity circumscribed by a peripheral support collar. Each socket lobe is truncated by a guide surface inclined from the opening at a radially outer edge of an adjacent socket flute into the cavity to form a tool clearance recess portion of the guide surface which defines the radial outer edge of the adjacent flute.

Abstract: An angle-drive screw is provided which has a screwdriver recess in its head, the side-walls of the recess being undercut by the provision of a number of bores extending transversely through the screw head and connecting with the screwdriver recess. The screw may be formed by a casting or moulding process.

Abstract: A threaded fastener having a recess or projection in a head for engagement with a jointing equipment is disclosed. The recess or projection is composed of a center portion and radial portions extending radially outward of circumference of the center portion. Each of the radial portions includes a pair of straight line section and a rounded corner to prevent stress concentration for providing substantial strength against press-molding and applied torque.

Abstract: A screw head is provided with ribs on some of the driver engageable surfaces. The rib is slanted outwardly from the screw axis by a small angle between 1.degree. and 10.degree..

Abstract: A combined socket is provided, whereby a screw can be driven either by a cross tipped Phillips type driver or by a square Robertson type driver. The wings of the socket have end walls that curve convexly to permit the end wall to be clear of the corner of the square, right down to the bottom of the end wall. The vertical side faces of the socket have portions inclined at different angles. The upper and lower portions are inclined respectively at a greater angle to the vertical and a smaller angle to the vertical as compared to the side faces of a conventional Robertson type socket allowing a Robertson type driver to contact the side faces part way along the faces.

Abstract: The adaptor comprises a nut (2) screwed onto the end of the connection element (1) and interacting with a two-way connector (4) adapted to ensure the connection between a screwing or unscrewing member and the connection element (1), an arrangement between the nut (2) and the connector (4) allowing the connector (4) to rotate in only one direction, and a spring insert (44) for the elastic support of the connector (4) on the end of the connection element (1).

Abstract: A cover for covering closure plugs and openings and the like comprises a generally circular plate with axially positioned and extending latching fingers for engaging the corners of intersecting walls of a tool cross slot upon rotation of the cover for releasably retaining the cover in place over the plug.

Abstract: This invention relates to a bushing structure having a bushing (1) and a polygonal flange (2) said flange initially being formed with a circular circumference (5) having an outer diameter equal to the diameter of the inscribed circle (14) of the polygon to be made whereafter by means of cold deformation the material of the flange at the location of the angles of the polygon to be made is forced to flow outwards by means of a die pressed into the flat surface of the flange, the die having projections, the inner surfaces of which are steep with respect to the axis of the die and the bottom surface of which run obliquely and arching by upwards and outwards the radial width of said projections decreasing from the center to both sides.

Abstract: A modified Phillips-type cruciform recess in a screw or the like, which provides a cling-fit with a driver by causing deflection of the flutes of the driver against the walls of the slot in the recess, comprises a central socket portion and radially extending slots adapted to receive the flutes of a suitable driving tool. Each slot is defined in part by a bottom surface of substantially uniform width which slopes radially inwardly and downwardly along the axis of the screw. The bottom surface joins two opposing surfaces which form the walls of the slot. The pairs of opposite slots in the cruciform pattern are not symmetrically located relative to a plane including the longitudinal axis of the screw, but are offset laterally in opposite directions with respect to such a plane. On insertion of a standard driver into the recess, the flutes of the driver are caused to flex into frictional engagement with the walls of the slots, thereby achieving the desired cling-fit.