Abstract: A double flush clinch stud includes adjacent clinch means of different diameters with planar end surfaces. The stud may be employed in forming an assembly wherein two metal sheets are joined in face-to-face contacting relationship. This assembly can provide a flush attachment on the outside surfaces of both sheets when the length of the stud is equal to the combined widths of the sheets. In an alternative embodiment, the top undercut groove can be adapted to be underfilled with the material of the top sheet. In this alternate configuration, the top sheet is effectively constrained between the head of the fastener and the second sheet while permitting the top sheet to pivot with respect to the second sheet.

Abstract: The invention relates to a function element (10) comprising a head part (14) with an annular bearing surface (12) and tubular rivet segment (16) that is provided on the side of the bearing surface of the head part and that extends away from said head part. The invention is characterized in that a tubular guide segment (18) is concentrically disposed relative to the tubular rivet segment and radially inside said rivet segment, wherein an annular gap is provided between the guide segment and the rivet segment and the guide segment projects beyond the free end of the rivet segment.

Abstract: A unified head for a staked fastener wherein the unified head is made from a first member in combination with a supplemental member, and the two members have at least one shared fiber. In a staking operation that forms the unified head, the operation is conducted in such a manner that a portion of a fiber, initially within the first member or the supplemental member, crosses the boundary therebetween creating the shared fiber, i.e., a segment of a single fiber is embedded in the first member and a segment is embedded in the supplemental member.

Abstract: One embodiment includes a system of joined structures that includes a first structure having a first aperture in a composite material. The first aperture has a first interior surface and a first minimum radial extent. The system further includes a second structure having a second aperture in a metallic material. The second aperture has a second interior surface and a second minimum radial extent at least approximately the same as the first minimum radial extent. The system still further includes a coupling device having a first shank section extending through the first aperture and a second shank section extending through the second aperture. The portion of the second shank section applies a first radial force to the second interior surface and the first shank section applies at least approximately no radial force to the first interior surface. The composite material proximate to the first aperture is undamaged.

Abstract: A self-piercing blind fastener comprising a mandrel having an elongate cylindrical shell mounted on a stem of such mandrel and which extends co-axially about a central elongate axis of the blind fastener, the shell having a radially extending flange at one end and a tail-end portion at the opposite end for insertion through a workpiece, the mandrel further having a mandrel head in operative engagement with the tail-end of the fastener for transmitting a setting force thereto during setting of such fastener, the blind fastener further comprising a longitudinally extending indenting member extending co-axial with and away from the tail-end of the blind fastener, which indenting member having a cross sectional area less than the cross sectional area of the shell.

Abstract: The invention relates to a method for connecting components (5), whereby at least one rivet (1) penetrates at least one component (5), and a closing head (6) is molded on the rivet (1) or any given molded part (1) by means of a molding machine. According to the invention, prior to the deformation of the closing head (6) on the rivet (1) or the given molded part (1), a rivet projection (U) is determined for the respective determination of the molding parameters, such as the molding course, molding time, and molding force.

Abstract: A force connection strut (1) of a chassis of a passenger car or utility vehicle is provided for the non-positive connection between a chassis and a wheel carrier, preferably an axle strut or a chassis control arm. An elongated basic body (G) and at least two end-side mount supports (5) are provided for introducing and leading out forces.

Abstract: A river body (40) is formed with cutting teeth (68) in a forward edge (66) of the rivet body. A mandrel (96) is formed at a forward end with an enlarged head (104) having a drill point (60) thereon. A plurality of the rivet bodies (40) are stacked on the mandrel (96), with the drill point (60). The rivet body (40a) is rotated and, through rotative coupling, the mandrel (96) is also rotated. The rotating drill point (60) forms pilot holes I workpieces (186) and (188), and the rotating cutting teeth (68) enlarge the pilot holes to form holes (192) and (194), respectively, for receipt of a cylindrical portion (42) of the lead rivet body (40a).

Abstract: The current invention is directed to a three piece blind fastener comprising a mandrel 40, a tubular body portion of 10 and a radially extending flange 14, wherein the cylindrical body 10 is mounted on an elongate stem 42 of the mandrel so as to extend co-axially about a central axis of such blind fastener, and the mandrel having a mandrel head in operative engagement with a tail end of the body for transmitting force there to during setting of the fastener, wherein the radially extending flange is separate from and held in crimped engagement with the body portion at or towards a front end of the tubular body so as to be axially remote from the tail end of such body.

Abstract: A die (18) for use in a self-piercing rivet setting apparatus comprises a cavity (25) for receiving therein a protruded workpiece zone consisting of respective portions of the workpieces (2, 3) to be protrudingly deformed toward the die through the pressure of the self-piercing rivet (1). The cavity has a bottom surface provided with a central raised portion (29) protruding from the center of the bottom surface toward a punch. The central raised portion of the cavity has a vertical angle in the range of 90 to 160 degrees. Preferably, the central raised portion has a top formed in a spherical shape. The cavity has an approximately cylindrical outer wall (27) in the periphery thereof. The cavity has a curved inner surface extending from the top of the central raised portion to the lower end (33) of the outer wall through the bottom (35) of the cavity.

Abstract: A blind rivet and a method of assembly comprising a tubular shell and mandrel in combination. The mandrel comprises a stem and a radially-enlarged head which in use forms a blind head to the shell to set the rivet, in which either the head of the mandrel or the bore of the shell is formed with a plurality of depressions the bases of which lie on a notional circle having a diameter which, where the depressions are formed in the head of the mandrel, is less than the bore of the shell or, where the depressions are formed in the bore of the shell, is greater than the diameter of the head of the mandrel. The depressions, which are preferably generally longitudinally disposed, define ribs, ridges or other protusions therebetween which in use and on pulling the mandrel into the shell bore extend radially beyond the bore of the shell, so that material of the shell becomes displaced by contact with the ridges and occupies the depressions. The invention may be applied either to pull-through, or self-plugging rivets.

Abstract: A fastener is used to connect a first link to a second link in a vehicle seat assembly. The fastener has a head portion and a body portion extending outwardly from the head portion and defining an external diameter. The body portion is generally cylindrical and has a central bore with an internal diameter that is less than the external diameter. The method for connecting the first link to the second link with the fastener includes the steps of inserting the central body portion through aligned apertures in the links to form a subassembly and holding the subassembly fixed while a tooling member applies a linear load to the distal end of the body portion. The tooling member is inserted into the central bore and deforms the body portion for engagement with the first and second links to allow relative rotational movement between the links while eliminating relative linear movement therebetween.

Abstract: A fastening element capable of being attached to a panel by deforming the panel is disclosed. A barrel portion is tubular with an open free end and has an axis defining a circumference. A radial flange portion is integral with the tubular barrel portion opposite the free end and defines a circumferential surface. The radial flange portion includes a plurality of projections spaced apart and extending outwardly from the circumferential surface. Each of the projections defines at least one wall generally perpendicular to the circumference about the axis of the barrel portion.

Abstract: The invention concerns a functional element, in particular a bolt, consisting of a shank portion (14) and a head portion (16) designed to be assembled riveted with a plate element, in particular a sheet metal part. The invention is characterised in that the head portion (16) is hollow and has practically the same external diameter as the shank portion. When mounted, the hollow head portion (16) of the functional element (10) forms a riveting edge (37) on one side of the sheet metal part and an annular groove (52) on the other side of the sheet metal part, the annular groove (52) acting as a flange. The invention further concerns a method for fixing the functional element in a sheet metal part and the resulting assembling element (16), as well as a matrix and a swaging assembly.

Abstract: The invention relates to a blind rivet, a rivet pin, a holding device, a method for producing a blind rivet and a method for creating a riveted joint which enables a permanent joint to be produced between several workpieces in one working cycle.

Abstract: A heatstake for fastening a workpiece includes a base portion (12) having at least one shaft portion (22). A central passage (30) extends though the shaft portion from its leading end (28) to the base portion. A plurality of slots (22) are disposed about an outer surface (34) of the shaft portion (22). The plurality of slots (32) have a predefined angular separation. Preferably, the plurality of slots (32) disposed about the outer surface of the shaft portion form a heatstake having multiple fastening portions. The multiple fastening portions are adapted to form a geometric flower shape for increasing the fastening strength of a heatstake when staked.

Abstract: The preferred embodiment of a fastening system includes a self-piercing fastener having a thread-like pattern. In another aspect of the present invention, a fastener insertion machine employs an electromagnetic actuator without fluid actuation. A further aspect of the present invention uses a rotary-to-linear transmission within the machine to advance the fastener. In still another aspect of the present invention a self-piercing fastener is a clinch nut or a clinch stud.

Abstract: An explosive assisted fastener for joining steel framing members. The fastener is comprised of an integrally formed member having a head section, a stem section and a tip section, such that the head section is disposed at a first end of the stem section and adapted to be linearly driven by a driving device into the framing members, and the tip section is disposed at a distal second end of the stem section and adapted to penetrate the framing members. The fastener further includes an explosive material embedded in the tip section of the fastener. In operation, the fastener is driven through the framing members until the head section of the fastener seats against an outer surface of the framing members. Once driven into place, the explosive material residing in the fastener is detonated, thereby radially expanding the tip section of the fastener and preventing removal of the fastener from the framing members.

Abstract: A method for placing a functional element, especially a fastening element, in an especially liquid-tight and/or gastight manner, on a metal part. The inventive method is characterized in that a functional element provided with a hollow head segment is pressed against the metal part (212) which is supported by a die (214) and the metal material is deformed into an undercut (324) by deforming the head segment when simultaneous deformation of the hollow head segment occurs and the metal pant is shaped in a forming area defined by parts (216) of the die (214). Said parts (216) are kept in a stationary position during the forming process but are partially removed from the die to enable the functional element which is placed on the metal part (212) to be extracted therefrom. The invention also relates to a die, a functional element, an assembly element and a die arrangement.

Abstract: A rivet is provided which includes axially opposite end portions at least one of which is more likely to be deformed radially outwards than a remaining portion thereof, and the remaining portion is more resistant to a load applied in an axial direction of the rivet than the axially opposite end portions. As one example, the rivet includes a head portion and a cylindrical portion that extends from the head portion, and a recess is formed in the head portion so as to be open to a top surface of the head portion.

Abstract: A rivet and method for riveting metal members, and particularly, metal sheets is disclosed. The apparatus includes a rivet assembly for driving a piercing rivet into stacked metal sheets and a die for assisting in supporting the sheets during driving of the rivet and for assisting in securing the rivets to the sheets. The rivet of the invention includes an adhesive that is forced through passages in the rivet for assisting in fastening the rivet to the sheets and for assisting in fastening the sheets to each other with greater strength.

Abstract: A joining pin (3.2) with which two parts (1 and 2) made from a porous material, particularly wood or a wood-like material, are to be joined together, is anchored in the porous material at predetermined anchoring points (31, 33). For this purpose, a bore (4.2) with a closed inner end (41) is made in the parts (1 and 2). The shape of this bore (4.2) is so matched to the joining pin (3.2) that it can be introduced substantially without force expenditure into the bore and is positionable in a first position. At least one predetermined anchoring point (31, 33) between the joining pin (3.2) and the wall of the bore (4.2) is formed when pressure is built up by pressing the joining pin (3.2) with a pressing force (F) more deeply into the bore to a second position. Energy is supplied in a planned manner to the joining pin (3.2) so that at the predetermined anchoring points (31, 33) the thermoplastic material of the joining pin (3.2) is plasticized.

Abstract: An assembly which includes a fastener assembly that clamps together two or more clamped components between clamping structures of the fastener assembly. One of the clamped components that the fastener assembly clamps together with the other clamped components is a clamp-force-check component that defines a fastener hole through itself. The clamp-force-check component is disposed adjacent one of the clamping structures of the fastener assembly. A fastener shaft of the fastener assembly extends through the fastener hole defined through the clamp-force-check component. The clamp-force-check component has an outer perimeter of such a shape that a wrench may engage the outer perimeter of the clamp-force-check component and apply a torque thereto.

Abstract: The present invention provides a method of joining a sheet metal part to a metal tube to form an assembly. In an overlapping configuration, the parts are held together under a clamping force while a self-piercing rivet is driven through the assembly by a welding electrode. The rivet pierces and passes through the sheet metal part and then through at least substantial portion of the metal tube to thereby form a mechanical interlock. An electrical current is then applied to this mechanical retention to melt a portion of the rivet as well as a portion of the metal surrounding the joining region. The flow of electrical current is then stopped after several welding cycles where the now melted material is allowed to solidify upon cooling, thereby forming a weld.

Abstract: A sheet metal assembly includes first and second metal sheets having flanges extending from the sheets. The flanges overlap and are in engaged parallel facing relation for a width between outer edges and flanges. At least one pair of self-piercing rivets joins the flanges at spaced locations along the width. The rivets each have a head and a shank extending into the flanges from opposite sides. The rivet heads of each pair are located in opposite flanges and are spaced further from the outer edges of their respective flanges (nearer the load-application ends) than are the shank portions of other rivets of the pair.

Abstract: A system for pivotably coupling components. The system comprises a pivot structure having a head, a body, a deformable retention feature and a stop. The stop is positioned to limit movement of a cooperating deformation tool to ensure predictable pivot spacing.

Abstract: The present invention is directed to a blind fastener, usually a blind rivet, (10) comprising a mandrel (22) and an elongate cylindrical body (16) mounted on a stem (24) of such mandrel so as to extend co-axially about a central axis A of such blind rivet, the body (16) having a flange (18) at one end and a tail end (20) at an axially opposed end, for insertion through a hole in a workpiece, the mandrel having a mandrel head (26) in operative engagement with this tail end (20) for transmitting force thereto during setting of such fastener, wherein the body (16) has two different external diameters (d, D) and a radially extending shoulder (32) therebetween such that the external diameter (D) of the body adjacent to the flange (18) is greater than the external diameter (d) of the body adjacent to the tail end, wherein the body between this shoulder (32) and the flange is at least partially encased in a resilient, shock absorbing material (36).

Abstract: A blind setting rivet assembly capable of permanently fastening sheet metal work pieces or the like together comprises a rivet body having a hollow tubular sleeve and an enlarged flattened head. The rivet body surrounds a mandrel that may have a weakened area to allow detachment of the mandrel shaft following application of sufficient axial force to the shank. This application of force sets the rivet by causing a tapered shoulder section of the mandrel to deform the rivet sleeve. The mandrel shank is terminated in a coring head that cores an aperture in the workpieces through which the rivet sleeve passes. The mandrel shank includes a weakened area of reduced diameter adjacent to the screw tip that allows detachment of shaft following application of sufficient axial force to the shank. This application of force causes the tapered shoulder section of the screw tip to compress and deform the rivet sleeve setting the rivet.

Abstract: The present invention is a self-piercing rivet wherein the hollow shell has an external axial asymmetry wherein the asymmetry is with respect to the axis of rotation of the hollow shell. Once installed in a stack of sheets, the asymmetric self-piercing rivet prevents relative sheet rotation of the sheets relative to the axis because of rotational interference caused by the external axial asymmetry of the hollow shell.

Abstract: The present invention is a self-piercing rivet wherein the hollow shell has an external spiraling, wherein the spiraling is with respect to the axis of rotation of the hollow shell. Once installed in a stack of sheets, the spiraling prevents the riveted sheets from mutually separating and the rivet loosening with respect to the sheets.

Abstract: A blind rivet system including a number of parts to be joined that have aligned holes. A tubular rivet body is disposed in the aligned holes and includes a rivet head portion and a sleeve portion. The head portion and sleeve portion include a longitudinal bore. A mandrel having a head portion greater in diameter than the bore and a shaft portion is disposed within the longitudinal bore. An adhesive is disposed in an annular space defined by the interior surface of the bore and an exterior surface of the shaft portion. An installation tool having a seal intersects with the rivet head portion such that when the head portion is drawn within the bore during installation, the adhesive is maintained within the tubular rivet body and extruded from the annular space to a region between faying surfaces of the parts to be joined.

Abstract: An elastic fastener 1 comprises a hollow tubular portion 7, an internally threaded portion 2 provided at one of the ends of the tubular portion 7, and a flange 9 formed at the other end of the tubular portion 7. The tubular portion 7 and the flange 9 are integrally formed of an elastomeric material, such as a styrene-based elastomer, a polyamide-based elastomer and a polyester-based elastomer. The internally threaded portion 2 is formed of a rigid resin material such as a polycarbonate resin. The internally threaded portion 2 is integrally fixed to the tubular portion 7 in a hole of the tubular portion.

Abstract: A threadedly engageable coupling device is used with a complementary coupling device for tightening first and second article pieces, and includes an abutment head, a cylindrical shank extending from the head, and a plurality of blade portions disposed on a proximate segment of the shank proximate to the head. Each of blade portions has a cutting edge which gradually deviates from the proximate segment when extending towards the head such that when the shank is inserted into a bore in the first article piece to permit the head to abut against the piece by a friction force generated through screw movement of a threaded surface of a distal segment of the shank and a threaded surface of the complementary coupling device, the cutting edge incrementally incises the first article piece so as to guard against rotation of the shank relative to the piece to thereby tighten the first and second article pieces together.

Abstract: A rivet and method for riveting metal members, and particularly, metal sheets is disclosed. The apparatus includes a rivet assembly for driving a piercing rivet into stacked metal sheets and a die for assisting in supporting the sheets during driving of the rivet and for assisting in securing the rivets to the sheets. The rivet of the invention includes an adhesive that is forced through passages in the rivet for assisting in fastening the rivet to the sheets and for assisting in fastening the sheets to each other with greater strength.

Abstract: The present invention is a self-piercing rivet wherein the hollow shell has an external spiraling, wherein the spiraling is with respect to the axis of rotation of the hollow shell. Once installed in a stack of sheets, the spiraling prevents the riveted sheets from mutually separating and the rivet loosening with respect to the sheets.

Abstract: The present invention is a self-piercing rivet wherein the hollow shell has an external axial asymmetry wherein the asymmetry is with respect to the axis of rotation of the hollow shell. Once installed in a stack of sheets, the asymmetric self-piercing rivet prevents relative sheet rotation of the sheets relative to the axis because of rotational interference caused by the external axial asymmetry of the hollow shell.

Abstract: A plastic fastener is disclosed. The fastener may be employed in a vehicle generator. The fastener has a plastic body extending through an aperture of a first component and through an aperture of a second component. The body has a first distal head that retainingly abuts the opening of the aperture of the first component. The plastic body also has a second distal head that retainingly abuts the opening of the aperture of the second component. The configuration of the body secures the first component to the second component. The invention further provides a method of fastening components of a vehicular generator. A plastic body with first and second studs is over molded about a first generator component. At least one stud may be extended through an aperture of a second generator component. The studs are then formed into distal heads to secure the first component to the second component.

Abstract: A peel type blind rivet (30) for securement in an aperture (9) of one or more workpieces (5,7), the rivet having a tubular shell (4) a flange (6) abutting one side of the workpieces, together with a mandrel (10) with a stem (8) extending through the shell and forming an enlarged head (32) adjacent to the tail end face (20) of the shell, whereby the head (32) has a plurality of axially extending cutting edges (36) for engaging with the body shell (4) the setting process of the rivet whereby when the stem (8) is subjected to a tensile load these edges (36) serve to split the shell into a plurality of segments (40) to engage with a remote side (5) of the workpieces.

Abstract: A self-piercing rivet comprises a flange with a large diameter and a shank with a hollow cavity extending from the flange inward. The rivet is made of aluminum or an aluminum alloy. The shank is a straight cylinder with outer diameter D1, and the hollow cavity in the shank has conical section tapered from the shank end and converging towards the flange at angle &agr; and a straight cylinder section with inner diameter D2 extending from the conical section to the end on the flange side. The shank has a substantially flat ring-shaped end with outer diameter D1 and radial length T1. The angle &agr; of the conical section ranges between 70° and 110°.

Abstract: The rivet (1) comprises a bearing head (2), a pulling stem (3) and an insertion body (4) which itself comprises:

Abstract: A flooring system includes a first floor member having a through hole and includes a second floor member having a non-through hole which extends from the bottom side toward the top side of the second floor member. The second floor member is positioned above the first floor member with the non-through hole aligned with the through hole. A radially-expandable fastener (such as a rivet) extends through the through hole and into the non-through hole. A method for installing a flooring system includes obtaining a first floor member having a through hole, obtaining a second floor member, and positioning the second floor member above the first floor member. A non-through hole is created extending from its bottom side toward its top side. A radially-expandable fastener (such as a rivet) is installed in the first and second floor members. The radially-expandable fastener extends through the through hole and into the non-through hole.

Abstract: A rivet capable of self-piercing at least one sheet of material and becoming embedded in one of such sheets, generally consisting of a head section and a shank section formed integrally with the head section, wherein the head section includes an upwardly and outwardly curved side wall surface extending from the shank section to an upper portion of the head section, and the shank section includes a recess in a lower end thereof, with the lower end of the shank section having a peripheral cutting edge sufficient to penetrate such material.

Abstract: A rivet having improved formability is provided. The rivet has a shank having a head at one end. The shank and the head have a refined grain structure. The rivet is manufactured from the region of the workpiece having a refined grain structure by first forming a region having a refined grain structure in a workpiece and then forming the rivet. The refined grain structure results in improved mechanical properties, such as formability, strength, toughness, ductility, corrosion resistance, and fatigue resistance. The improved formability of the rivet reduces the formation and propagation of cracks during the manufacture and installation of the rivets.

Abstract: An enhanced pop rivet capable of joining materials that may not be joined using a conventional pop rivet is provided. The pop rivet has contains a detachable shank that exposes a sharpened brad when removed. A user may then impale a second material with the sharpened brad so that the second piece of material becomes securely attached.

Abstract: A rivet capable of self-piercing at least one sheet of material and becoming embedded in one of such sheets, generally consisting of a head section and a shank section formed integrally with the head section, wherein the head section includes an upwardly and outwardly curved side wall surface extending from the shank section to an upper portion of the head section, and the shank section includes a recess in a lower end thereof, with the lower end of the shank section having a peripheral cutting edge sufficient to penetrate such material.

Abstract: According to an embodiment of the present invention, a fastening assembly has a first component containing a first aperture and a second component containing a second aperture. A pin made of a super-elastic alloy defines a shank with a bore having an axis, the shank being at least partially constrained within and juxtaposed with both the first and second apertures. Activation of the super-elastic alloy generates a retaining force normal to the axis of the pin, fastening the components together. Several embodiments are shown where a unitary pin fastens the components, while other embodiments are shown where the super-elastic properties of the pin are activated by another independent element of the fastener, for example a retainer that co-acts with the pin to fasten the components together. Activation forces can be applied to the pin through relative motion, or stretching against a shoulder.

Abstract: A fastening element for doubleglass panels has a threaded bolt having a forward end and provided with an expansion cone at the forward end, an annular expansion element pushed onto the expansion cone for expansion in a hole drilled in a rear glass panel and provided with an undercut in a region of a bottom of the drilled hole, a cap placed on the expansion element and resting against an end face of the threaded bolt, and a spacing sleeve arranged on a shank of the threaded bolt so as to rest against the rear glass panel and to pass through a front glass panel, the spacing sleeve having a portion engageable in the hole drilled in the rear glass panel and providing an abutment for the expansion element.

Abstract: A self-piercing rivet has a hollow deformable shank (10) with a piercing edge (11) for insertion into sheet material (14,A,B). A piercing end of the shank is covered by a cap (12, 30, 40, 50, 60 71) of material. The cap deforms around the shank and its piercing end as the rivet is inserted into the sheet material, and acts as a top layer of sheet material. This ensures that the piercing edge does not perforate the sheet material, enabling use of the rivet to join very thin sheets of material, or in tile case of a rivet stud, enabling its insertion into a single sheet of material.

Abstract: A temporary fastener that fastens two adjacent workpieces. The fastener includes a shank that extends through a hole of the workpieces. Extending from one end of the shank is a conical shaped head. The fastener also contains a pull stem which has a head located adjacent to the blind end of the shank. The stem head is pulled through the shank to expand and tightly fasten the shank to the workpieces. The fastener is removed by drilling through the head and the shank. The diameter of the conical shank head is smaller than the diameter of the drill so that part of the head does not become attached to the drill bit and scratch the workpiece. The conical shape of the head also reduces the volume of fastener material to further reduce the size and amount of chips produced during the drilling process. The tightly engaged shank prevents the fastener from rotating during the drilling operation.

Abstract: A method for creating a hole for a permanent fastener that replaces a temporary fastener that fastens two adjacent workpieces. The temporary fastener includes a shank that extends through a hole of the workpieces. Extending from one end of the shank is a conical shaped head. The temporary fastener has an inner channel that extends through the shank from the head to the opposite end. The fastener also contains a pull stem which has a head located adjacent to the blind end of the shank. The stem head is pulled through the shank to expand and is expanded to tightly fasten the shank to the workpieces. The fastener is removed by drilling through the head and the shank. The diameter of the conical shank head is smaller than the diameter of the drill so that part of the head does not become attached to the drill bit and scratch the workpiece. The conical shape of the head also reduces the volume of fastener material to further reduce the size and amount of chips produced during the drilling process.