Abstract: A fastener system is constructed wherein the installation and removal drive surfaces intersect an enlarged core diameter in a transitional surface that extends between the installation and removal surfaces of adjacent wings. The transitional surface has a concave form that conforms to the core diameter. The projections of the driver in the system are formed in a blunt shape.

Abstract: Interference surfaces are constructed on inner transition surfaces between wings of a fastener having a spiral recess. A portion of the transition surface is tapered to provide the interference. A standard driver for a spiral recess will engage the interference surface to create a “stick fit” engagement. The punch is formed using a wire EDM operation to construct tapered surfaces within the die cavity of a hob. The hob is machined down to obtain the desired depth, which is measured up from a gage spot indicative of the sticking point.

Abstract: A fastener which includes a recess that includes a plurality of alternating lobes and recesses, where each of the flutes and lobes is twisted or angled. The fastener can be driven using a conventional multi-lobular driver. Alternatively, a driver which also has angled or twisted flutes and lobes can be used to engage the recess and drive the fastener. A punch pin includes a head that has a plurality of alternating lobes and recesses that are twisted or angled. The head of the punch pin is configured to punch the recess into the head of the fastener. A device retains the punch pin such that the punch pin can rotate out of the recess after the punch pin punches the recess into the head of the fastener.

Abstract: A screw with a recess in the head of the screw comprises a screw head; a recess formed in the screw head; a plurality of blocks protruded from a periphery wall of the recess; each block having at least two inclined walls; each of the inclined walls having a slope identical to a slope of the wall. Each block has two inclined walls; and the connection of the inclined walls belonging to one block is formed as an acute angle. Or each block has three inclined walls which are formed as a trapezoidal shape.

Abstract: A screw has a convenient head, wherein an engaging concavity is defined. Said engaging concavity includes a central portion and a plurality of radial recesses disposed around and in communication with the central portion. Each radial recess has two insides with one inside parallels to the extension line and the other inside encloses an angle with the extension line, an end surface and an opening with a smaller width defined on the junction of the recesses and the centre portion.

Abstract: Interference surfaces are constructed on inner transition surfaces between wings of a fastener having a spiral recess. A portion of the transition surface is tapered to provide the interference. A standard driver for a spiral recess will engage the interference surface to create a “stick fit” engagement. The punch is formed using a wire EDM operation to construct tapered surfaces within the die cavity of a hob. The hob is machined down to obtain the desired depth, which is measured up from a gage spot indicative of the sticking point.

Abstract: The invention provides a screw head having a hexalobular slot (2) in the upper surface of the screw head, an upper peripheral wall (9) of hexalobular planform extending down into the screw head, the upper peripheral wall (9) being parallel or near parallel to the axis of the screw, a sloping transition surface (15) extending downwardly and inwardly with respect to the lower edge of the upper peripheral wall (9), and a tapered 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 screw head is engaged by a tool (6) having upper (16) and lower engagement (17) sections, the lower engagement section (17) is tapered, and there is a ‘stick fit’ between the surface of the tapered recess (11) and the external surface of the lower tapered engagement section (17), and there is no engagement with the sloping transition surface (15).

Abstract: The fastener of this application is designed to facilitate the insertion of rotating power driven tools into the fastener recess. The recess of this fastener generally uses spirally configured driving surfaces and is formed in a counterbore in the upper surface of the fastener. The driving lobes have upper surfaces that are depressed a distance into the counterbore. A ramp surface is formed on each of the upper surfaces that causes a spinning bit to fall into the recess in an engaged manner. The ramp surfaces are constructed with both removal and installation ramp portions.

Abstract: A drive system for a surgical fastener is composed of a drive tool with a drive tip that mates closely with the recess formed in the head of a threaded fastener. The surgical fastener has a head with a quadrilobe fitting therein which closely mates with the quardilobe tip of the tool. The cooperating drive surfaces align the fastener and tool coaxially and produce four point contact equidistant about the circumference of said fastener significantly reducing angular excursions of the fastener during placement in the bone.

Abstract: A fastener is configured for use in the manufacture of molded plastic components that will be subsequently attached to other components by the fastener. The low profile head portion of the fastener has a rounded contoured and convoluted top surface to facilitate the flow of plastic material around the head portion during the molding process. The underside of the head portion is formed with a square face surrounded circumferentially by circumferential land surfaces that provides a high pull-out force resistance for the fastener. The square face on the underside and convoluted top surface of the head portion provides a high spin-out torque resistance without sacrificing the pull-out force resistance. The rounded edges of the head portion are compatible with molding processes to allow the flow of plastic material to fully encapsulate the head portion within the molded plastic component.

Abstract: A screw and a screwdriver of the present invention provide an easy insertion of screwdriver bits and the screwdriver conveys a large torque when fastening so that the screwdriver does not rise up from the screw and does not damage recesses to fasten and loosen the screw. The screw has a high strength structure for shear force. A plurality of recesses for the insertion of the bits of the screwdriver are disposed on a top face of a screw head of the screw. Engaging walls are disposed to engage with the bits between the recesses. The whole shape of the recesses has a tapered cross section. Vertical engaging faces are formed inside the recesses near an outer circumference in a fastening direction of the screw and extend to a thickness direction of the screw head. The vertical engaging faces are parallel to bisectors of the width of the engaging walls through a central axis. The screwdriver has the bits having the same shape as the recesses of the screw head with respect to the central axis.

Abstract: A screw (10) has a threaded shank (12) and a head (14). The head has a recess (18) that comprises three lobes (18a, b, c). Each lobe is separated by a curved drive flange (20a, b, c). A driver (100) has a drive tip (114) that fits the recess of the screw.

Abstract: System comprising a crew and a tool (6) therefore, in which the screw head (1) with a slot (2), the slot (2) having a first recess (3) with an approximately straight-walled cross section, and the tool being provided with an engagement section (16) that is complementary to the first recess (3). The slot has a second recess (11) at the bottom of the first recess (3), with a smaller diameter than that of the recess (3), and the tool (6) is provided with a central point (17) that complements the second recess (11). The second recess (11) has a circular cross section and the central point (17) has a circular cross section.

Abstract: A catch assembly that locks a handle onto the spindle of a lock mechanism has enhanced resistance to attempts to remove the handle by forcibly driving the catch assembly inwards. The catch assembly includes a base mounted on the spindle having a threaded opening that receives a corresponding threaded retaining pin. The pin is moved axially by rotating it. When the pin is rotated to an outward position it engages the handle and the threads act to prevent the pin from being forcibly driven inward by transferring axially applied forces to the base. In the preferred design, the head of the retaining pin is softened and specially shaped to limit the torque that can be applied.

Abstract: A combination of a screw and a screw driver bit and a header punch for its manufacture capable of effectively preventing a come-out phenomenon of the screw driver bit by improving the structure of a groove part in a cross groove part in a cross groove of a screw to prevent a conventional damage.

Abstract: A drive socket for a male threaded fastener includes a plurality of rounded lobes of equal radius which are located equidistant from the center of the fastener and an equal distance from each other. The drive socket also includes flat surfaces located opposite the lobes and equidistant from the center of the fastener. Another embodiment of a drive socket includes a first set of lobes and a second set of lobes, each lobe being of equal radius and equidistant from the center of the fastener. The lobes of the first set are equidistant apart and the lobes of the second set are also equidistant apart and equidistant apart from the adjacent lobes of the first set on either side of the lobe of the second set. Each of the lobes of the first set includes a flat surface which is adjacent and tangential to the radius portion of the lobe.

Abstract: A fastener for use in forming a joint of a framework for a patio enclosure. The joint includes an end of an elongated first frame member fastened to a side of an elongated second frame member. The fastener includes a body having a first end and a second end defining an outer surface therebetween. The second end is adapted to fit in a hollow portion of the first frame member. The fastener further includes a plate extending outwardly from the body. The plate is adapted to be fastened to the side portion of the second frame member. A stop extends outwardly from the outer surface of the body. The stop provides for positioning of the fastener relative to the first frame member when the second end is positioned within the hollow portion of the first frame member.

Abstract: Recessed head fasteners are provided with a configuration by which the force applied by the blades of the driver to the recessed wings is applied at the radially outer regions of the wings. The wings of the fastener recess may be provided with torque pads at the outer regions of the wings adapted to engage the outer portions of the driver blades. The torque pads may be defined by relieved regions on the drive walls of the recess wings. The relieved regions are formed to avoid contact with the driver blades. Stabilizing ribs also may be defined at the radially inward regions of the drive walls. A recess engageable driver may include a plurality of radially extending ribs configured to promote engagement of the ribs with the most radially outward regions of the recess drive walls. The driver and the recess are compatible with each other as well as with otherwise corresponding conventional recesses and drivers that do not incorporate the invention.

Abstract: A driver bit and a header punch for manufacture of screws comprising a screw comprising substantially vertical end wall portions of predetermined depth formed on an end edge portion of a bit fitting groove on a screw head, non-planar bottom portions raised from lower edge portions of the vertical end wall portions toward a center of the screw head, inclined groove portions extending from raised portions of the non-planar bottom portions toward a center of a screw neck, a substantially conical-shaped bottom surface formed on a bottom of the groove, the bit fitting groove being adapted to a driver bit, which has a blade adapted to be fitted into the bit fitting groove and has a lower edge portion of the blade adapted to abut against the non-planar bottom portions.

Abstract: A screw with a thin head comprising a screw head (2) and a shank (4), and with its top (5) forming a circular arc of a large radius has an unthreaded part (20) tapered down between the bearing surface (6) and the thread (3) and has a radius (21) connected to the thread portion (3), and therefore it will be readily produced to be used for compact products and correspond with thin products. And the radius (21) is connected to the unthreaded part (20) of the shank on one hand and to the screw ridge (3) on the other, preventing stress concentration at this part from occurring at time of fastening and a long time after the fastening of the screw, so ensuring a fastening strength, without causing a fatigue fracture. And further, when heating and plating treatments have been given to the screw, as the top of the screw head is not flat, there is no possibility of the heads of the screws being stacked to each other in the course of mass production, ensuring stable heat and plating treatments.

Abstract: A screw fastener (10) including an elongate shank (11) having a longitudinal axis (A), a tip (12) at one end of the shank (11), a head (13) at the opposite end of the shank (11), and a self-tapping screw thread (14) extending along at least a major portion of the shank (11). The head (13) includes a generally planar end face (17) which is generally perpendicular to the longitudinal axis (A), and which includes means (18) for cooperation with a screw driver. The head (13) further includes boring means (15) that permits the head (13) to bore into a sheeting substrate (20). Control means (19) are provided for controlling the depth of penetration of the head (13) into the sheeting substrate (20).

Abstract: New system for holding and fastening screws comprising a screw head provided with a mortise hole (1) having a tapered configuration along the screw longitudinal axis, said mortise hole (1) having a number of lugs (2) and the corresponding circular sections (3); and comprising a suitable screwdriver o fastening tool head tip (4) having a definite shape and wings (5), both according to the corresponding number of lugs (2) in order to match said screw head mortise hole (1); and comprising the required punching mortise die tool for the definite conformation of said screw head mortise hole (1) and said screwdriver or fastening tool head tip (4).

Abstract: Disclosed is a screw with an improved head, in which a stress-relieving notch is formed at each corner of a driving recess on the screw head. The stress-relieving notch is in an equal arcuate shape. Apart from the well known slotted or Phillips one, the driving recess is also available with a triangle, square, hexagonal, or any other multiangular form in section.

Abstract: A screwdriver bit (50) fitted to a screw wherein generally vertical end wall parts of a specified depth are formed in the bit fitting grooves of a screw head part at the end edge parts, a generally flat bottom part is formed directing from the lower edge part of the vertical end wall parts to the center part of a screw neck part, and a conical bottom surface is so formed at its center part, comprising flat blade parts (52) forming, at the top end parts, generally vertical end edge parts fitted into the bit fitting grooves of the screw head part along the vertical end wall parts, the top end surfaces of the flat blade parts being formed in a conical protruded part (54) having an inclination angle &thgr; of approx.

Abstract: A driver bit and a header punch for manufacture of screws comprising a screw comprising substantially vertical end wall portions of predetermined depth formed on an end edge portion of a bit fitting groove on a screw head, non-planar bottom portions raised from lower edge portions of the vertical end wall portions toward a center of the screw head, inclined groove portions extending from raised portions of the non-planar bottom portions toward a center of a screw neck, a substantially conical-shaped bottom surface formed on a bottom of the groove, the bit fitting groove being adapted to a driver bit, which has a blade adapted to be fitted into the bit fitting groove and has a lower edge portion of the blade adapted to abut against the non-planar bottom portions.

Abstract: A combination sidewalk bolt is provided. The bolt includes a head portion, a threaded shaft portion extending perpendicularly outward from a first side of the head portion, a Phillips head recess well formed within a second side of the head portion for use in driving the bolt, and a slotted screwdriver slot provided in the second side of the head portion. A depth of the recess well is greater than the width of the head portion between the first side and the second side.

Abstract: Screws with compound threads. Each of the screws includes a head with a compound drive recess therein. The compound drive recess for the screw driver(or the screw drive bit) is shaped to have four symmetrical fan-shaped portions, a center square portion with four faces, and eight chamfer edges intermediate to the center square portion and each of the four fan-shaped portions. The compound drive recess allows the screw to be driven by various screw driver such as slot, Phillips, square, Pozi and cross-square. The compound drive recess can be driven by its tailor-made driver, which gives the compound drive recess the capacity to withstand high driving torques with minimal drive bit slip or cam-out.

Abstract: A screw includes a shank and a head. The head includes a driving socket having a long slot that extends axially into the head to a depth. A first short recess is defined in a bottom wall defining the long slot and extended along a longitudinal axis of the long slot, the first short recess being narrower yet deeper than the long slot. A second short recess extends along an axis that is normal to the longitudinal axis of the long slot. The second short recess is as deep as the first short recess, the short recesses together defining a cross-shape recess for receiving a Phillips type screw driver, the cross-shape recess including four ends. The driving socket of the head further includes a square recess that is located within an area defined by the four ends of the short recesses, the square recess being adapted to receive a square socket type driver. The square recess extends axially into the head to a depth deeper than the short recesses.

Abstract: A screw with a recessed head (3) has a crossing recess (4) formed in a top of the head and consisting of a central region (5) and four grooves (6) extending radially from the central region. Each groove is tapered to reduce width towards an outer conical bottom (9), which defines the groove together with opposite side walls (7, 8) transmitting torque. The bottom connecting outer edges of the side walls has a width ‘A’ larger than width ‘a’ in the widely used standard recesses of the same length ‘M’. The side walls have a radial length ‘B’ smaller than ‘A’, and distance ‘C’ between the intersections of two side walls of different grooves is equal to or larger than the product of 1.5 and ‘A’. One side wall (7) lies in a flat plane in parallel with the screw's axis, and is located forward in a tightening direction of the screw. The conical bottom (9) slanted 5° relative to the axis provides a conical sticking surface.

Abstract: Recessed head fasteners are provided with a configuration by which the force applied by the blades of the driver to the recessed wings is applied at the radially outer regions of the wings. The wings of the fastener recess may be provided with torque pads at the outer regions of the wings adapted to engage the outer portions of the driver blades. The torque pads may be defined by relieved regions on the drive walls of the recess wings. The relieved regions are formed to avoid contact with the driver blades. Stabilizing ribs also may be defined at the radially inward regions of the drive walls. A recess engageable driver may include a plurality of radially extending ribs configured to promote engagement of the ribs with the most radially outward regions of the recess drive walls. The driver and the recess are compatible with each other as well as with otherwise corresponding conventional recesses and drivers that do not incorporate the invention.

Abstract: A mechanical clamp used to secure hoses includes an elongated band. The band surrounds a central region and has a sequence of slots along its length. An adjustment screw has a hexagonal head that rotates about a longitudinal axis and has a thread that extends into the slots. Rotation of the screw adjusts the area of the central region. The head of the screw allows a driver to transfer torque to the head of the screw at an angle from the axis of rotation. The head is either curved or angled to allow a driver to efficiently engage the head of the screw during rotation when placed at an angle to the axis of rotation.

Abstract: The drywall screw includes an elongated shaft about an axis, a screw head at one end and threads about the shaft. The screw head has a recess having upper and lower portions. The upper portion is comprised of an upwardly flared thin-walled section having convex and concave interior and exterior surfaces, respectively. The lower portion includes a Phillips head slot for receiving a Phillips head driver. The recess in the head of the drywall screw and the outwardly flared head enables the screw to be driven into the drywall without tearing or loosening the paper overlying the drywall, while simultaneously providing a sufficient recess for receiving the drywall mud finishing compound. In a further form of drywall screw, the upper portion of the screw head is formed by a thin-walled portion defining a conical surface of revolution about the axis of the screw.

Abstract: A threaded fastener for securing a first material to a support member is provided comprising a tapping or tap screw point at a first end, a threaded shank with three separate leads, a first portion of the shank, adjacent to the tap screw point, being of a trilobular thread design, a second portion of the shank, distal from the tap screw point, being unthreaded, and a head at an end opposite the tap screw point having an enlarged diameter and a countersunk shape to reduce the likelihood of pull through of the fastener through said first material, yet to allow the head to be introduced flush with a surface of the first material.

Abstract: A spiral drive system for threaded fasteners includes driver-engageable surfaces on the head end of the fastener in which at least some of the driver-engageable surfaces are defined by a spiral segment configured to maximize torque transmission while spreading the driving load over a broad driver-fastener interface to reduce the risk of development of high stress regions. Drivers and related tooling also are disclosed.

Abstract: There is provided a trocar button having an enlarged flat head at the larger exterior end connecting with a conical body and a pointed bulbous end. The large part of the conical body connects with the enlarged flat head. Between the small part of the conical body and the pointed bulbous end there is a neck. In the body of the trocar button including the enlarged flat head, the conical body, the neck, and part of the pointed bulbous end, there is a cavity. With the removal of the pointed bulbous end at the neck, there is created a through passageway in the trocar button. A needle attached to a syringe, can be inserted in the through passageway and into the interior of the cadaver. Then, an embalming fluid can be forced through the needle and into the interior of the cadaver. Also, the through passageway allows gas in the cadaver to escape. Further, if there be a liquid in the cadaver some of that liquid can collect in the passageway. On the exterior of the conical body there is a thread.

Abstract: The drywall screw includes an elongated shaft about an axis, a screw head at one end and threads about the shaft. The screw head has a recess having upper and lower portions. The upper portion is comprised of an upwardly flared thin-walled section having convex and concave interior and exterior surfaces, respectively. The lower portion includes a Phillips head slot for receiving a Phillips head driver. The recess in the head of the drywall screw and the outwardly flared head enables the screw to be driven into the drywall without tearing or loosening the paper overlying the drywall, while simultaneously providing a sufficient recess for receiving the drywall mud finishing compound.

Abstract: A cross-recessed head screw has in its head a tool engagement recess including first releasing surfaces which are adapted to be engaged with generally flat front edges of an end of a cross-headed tip screwdriver and have the function of moving the screwdriver backward when the screwdriver is turned in the reverse direction for loosening the screw. The tool engagement recess further has second releasing surfaces each contiguous to a corresponding one of the first releasing surfaces and serve to guide the backward movement of the screwdriver as the latter is turned in the screw-loosening reverse direction. By virtue of engagement between the first releasing surfaces and the front edges of the screwdriver, the reverse rotation of the screwdriver produces only a small friction torque which is quite insufficient to cause rotation of the screw in the screw-loosening direction.

Abstract: A screw includes a head and a shank which extends from one side of the head, a substantially cubic recess defined by four sides in the other side of the head, each of the four sides having a short slot perpendicularly outwardly extending therefrom and each of the four short slots communicating with the cubic recess.

Abstract: A threaded fastener which is constructed to be turned in one direction by a square socket drive includes a threaded stem and an integral modified head arranged with four raised projections which are circumferentially spaced. Each of the four raised projections includes a substantially flat wall portion and a curved and inclined ramp portion. The four flat wall portions effectively define a square center region which is compatibly sized to receive a one-half inch square socket drive. Rotation of the square socket drive in a counterclockwise direction causes the sides of the square socket drive to engage the flat wall portions so as to turn the threaded fastener in a counterclockwise direction. Any attempt to rotate the square socket drive in a clockwise direction causes the sides of the square socket drive to ride up along the ramp portions and ride out of engagement with the modified head of the threaded fastener.

Abstract: The screw, of the type provided with a coaxial recess adapted to mate with the tip of a screwing tool has in plan view a configuration in the overall form of a star with six chamfered points, with the lateral walls of the recess flared outwards and inclined to the screw axis by an angle of between 7 and 15 degrees. The sides of the chamfered points of the star consist of flat surfaces, pairs of which form on the lateral wall of the recess six corresponding ribs of isosceles triangle cross-section, the angle at the vertex of the isosceles triangle being substantially 90 degrees and the height of the triangle being substantially equal to one half the base length of said isosceles triangle. The screwing tool has a tip which mates with the lateral walls of the screw recess.

Abstract: An eagle wing tips tamper-proof fastener and driver tool with complementary driver head contact for operating the same. A conventional threaded shank is perpendicularly connected to a substantially flat head. The head comprises a plurality of recessed channels numbering three and the channels radially curve outwards from a common center point. In one embodiment, the substantially vertical right and left walls of each channel allow application of torque with the driver tool in both directions. In an alternate embodiment, the substantially vertical right wall and the surface of the substantially inclined left wall allow application of torque with the driver tool to the right only.

Abstract: A fastener system includes a fastener and a driver tool in which the fastener includes a cavity for insertion of the driver tool and in which the driver tool and the fastener form an interlocking relationship between the driver tool and the fastener is formed by having a portion of the fastener overlie a portion of the driver tool. This interlocking relationship prevents accidental separation of the driver tool from the fastener and consequent marring of the surfaces of the work pieces being joined together and also prevents stripping of the driver tool and the fastener cavity.

Abstract: A screw for snugly-fitted tightening pairs, of the type having a lobate head or a lobate-socket head (31), in which each lobe (37) is formed of one face (37') directed in a substantially circumferential manner and two other substantially parallel faces (35, 36) directed inwardly of the screw; said screw is provided with a reaction surface (33) with a tightening wrench (32). The portions of said reaction surface (33) included between two adjacent lobes are comprised each of a pair of faces (38, 39) inclined to each other to form an angle concave towards the outside of the screw, so as to constitute a reaction surface with a wrench of a polygonal profile. Such a screw can be operated to advantage either with the polygonal wrenches of the known art, or with an innovatory mating wrench of a lobate configuration.

Abstract: A recessed screw has a recess formed in the head of screw, with the recess being defined as a superimposition of two equilaterally-triangular recesses each having vertices shaped arcuate and arranged coaxially with a phase shift of 60.degree. around the screw axis. The recess thus has alternating six grooves and six driven vanes having side walls extending parallel with the axis, and an inner ridge of vane is a conically curved sticking wall inwardly slanted towards a bottom of the recess. A cross-sectional area of groove is larger than that of each vane. A driver bit has six driving vanes in conformity with the grooves and six valleys each interposed between the adjacent driving vanes and corresponding to the driven vanes in the recess, such that a biting action appears between the recess and bit, the driving vanes can be strengthened, and any conventional bit for Torx screws can be used with the recessed screw.

Abstract: A threaded tubular fastener having an elongated central through-bore having engaging means for engaging said through-bore with a rotary device having a rotary driver, a generally cylindrical body having an external surface with a main external thread formed thereon with a plurality of slots, said thread being larger than the diameter of a pre-drilled hole in a first work piece and a second mating work piece wherein the said threaded tubular fastener is employed to fasten the first work piece to the second work piece.

Abstract: A driver assembly for driving fasteners into a workpiece comprises a multilobular fastener engaging portion for engagement in a complementary multilobular socket or recess on a fastener. Each lobe is bounded on opposite sides by a flute, and each lobe includes a driving side wall and a trailing tapered side wall. The driving side walls are adapted to contact the complementary lobular portions of the fastener for applying torque to the fastener, while the trailing tapered side wall is aligned to contact the complementary lobular portion in wedged engagement at a point when the fastener is applied to the fastener portion. A fastener socket is also provided having a driven side wall and a trailing tapered side wall, which is constructed substantially similarly to the tapered side wall of the drive bit and which provides similar attributes.

Abstract: The invention herein disclosed involves a "tamper-evident bolt". More specifically, the bolt has ratchet or splined teeth on the outer periphery of the bolt head which will accept a socket for tightening the bolt. In the center of the head of the bolt is a sealed or capped blind axial recess. The recess is fitted to accept a driver to release the bolt. In a specific embodiment the blind axial recess has ratchet teeth. A seal or cap is received within the blind axial recess such that the seal or cap must be removed for access to the bolt releasing means, thereby indicating the possibility of unauthorized tampering with the bolt.

Abstract: For its drive a screw is given a recess, which has an outer contour diverging from the circular shape. In the radial inner area and/or radial outer area of the recess the side walls are formed by individual surfaces located on a conical surface.

Abstract: A tamper-proof drive system including a drive tool and a complementary nut or fastener drive head each having a body defining a central axis and a drive portion formed in an end surface of the body about the central axis. The drive portion defines a plurality of symmetrical lobes in a circular array. The lobes are defines by three series of arcuate surface, two of which may be generated from circular or elliptical configurations while the intermediate surface is partially circular.

Abstract: A threaded fastening member includes an actuating end having a head. The head has a diameter projecting beyond a diameter of the thread of the fastening member and is coaxial with a thread axis. A centrally located recess is provided within the head for the application of interior forces. The recess includes radial outwardly projecting slots, each having two flanks lying in respective planes. Each flank plane is essentially tangential to an imaginary cone that is co-axial with the thread axis. The recess further includes a pair of segmented circumferential faces separating each slot from an adjacent slot, and a transitional linear inner edge formed between each pair of segmented circumferential faces and each flank of a respective slot.