Abstract: A twist drill includes a cylindrical body having an axis of rotation therethrough and having a forward end which contacts a workpiece. The body has a spiral flute formed in an outer peripheral surface thereof so as to extend spirally along a length thereof to the forward end and a land disposed adjacent to the flute. The flute has a first wall facing in the direction of rotation of the body and a second wall extending from an inner end of the first wall to the outer periphery of the body. The first wall terminates at the forward end in a first cutting lip having a radially outermost end disposed on the outer periphery of the body. The second wall is concavely shaped when viewed from the forward end and formed so that, assuming a first line extending from the outermost end perpendicular to a second line which connects the outermost end and the axis of the body, the maximum distance between the first line and the second wall is set to range between 0.45 D and 0.65 D, wherein D is a diameter of the body.

Abstract: This invention relates to a nicked cutting tool suitable for cutting fiber-reinforced composite materials. It has an even number of twisted grooves and lands on the cutting part and the lands have nicks thereon. The nicks are preferably designed so as to incline to the longitudinal axis of the tool, and the nicks on two lands adjacent to each other in the circumferential direction incline in opposite directions to the longitudinal axis of the tool. It is possible to design the nicks so as to incline with regard to the tangent of the helix line of the twisted grooves, and in this case, the nicks on two lands adjacent to each other in the circumferential direction incline in opposite directions with regard to the helix line. In the rotation of the tool, the lands having nicks inclining in opposite directions contact alternately with the workpiece, and the fibers of the workpiece are thereby cut securely, and the shavings are discharged smoothly. The heat generated when cutting can also be dispersed.

Abstract: The drill tool for drilling a drilled hole with an undercut in a wall has a drill tool shaft having a drill head at a free end of the drill tool shaft, a depth insertion stop formed on the drill tool shaft to limit an insertion depth of the drill tool in the drilled hole and cutting elements projecting laterally from the drill head for making the undercut. The drill tool shaft (15) has an enlarged portion (10) acting as a pivot bearing for making the undercut spaced approximately equally from the insertion depth stop (4) and the drill head (6). To prevent sticking of the drill tool in the drilled hole the drill tool shaft (15) also has a cylindrical step portion (11) connected to the enlarged portion (10) and located between the enlarged portion (10) and the insertion depth stop (4). A discontinuous transition between the enlarged portion (10) and the cylindrical step portion (11) forms a scraping edge (12) and the cylindrical step portion (11) has a diameter less than a diameter of the enlarged portion (10).

Abstract: A twist drill has a cutting member at the bottom, a shaft at the top, and a reduced-diameter root clearance region between the cutting member and the shaft. Cutting edges are provided at the transition between the cutting member and the root clearance region, and further cutting edges are provided at the transition between the shaft and the root clearance region. After a throughhole has been drilled using the cutting member, the drill is displaced laterally and moved along a circular path while it is still rotating. As a result, the cutting edges at the transition between the cutting member and the root clearance region countersink the bottom end of the throughhole. A similar procedure is employed to countersink the top end of the throughhole using the further cutting edges at the transition between the shaft and the root clearance region.

Abstract: An improved drill bit having a shank of larger diameter than the body of the drill has an intermediate section rearward of the point section of the drill of smaller diameter than the point, and a longitudinally elongated, enlarged diameter root section joining the rear end of the intermediate section to the shank. The reduced diameter of the intermediate section provides a clearance space, preventing rubbing of the wall of a hole drilled by the bit, while the enlarged diameter root section increases the resistance of the bit to breaking. An improved method of making the enlarged-root drill bit includes inclining a relieving wheel at a substantially smaller angle to the longitudinal axis of a blank than the angle at which the blank was fluted. In one embodiment having a front tapered tip made by the novel method, rearwardly directed teeth are formed at the rear plane of the drill point, by fluting and relieving steps alone, without requiring an additional machining step.

Abstract: A drill having a pair of cutting edges formed at one end of a shank and arranged symmetrically with respect to a point, each cutting edge comprising a central edge portion and an outer edge portion, the central and outer edge portions each extending substantially straight and being joined to each other with an obtuse angle formed therebetween when seen from below, the central edge portion being formed with a central face substantially parallel to the axis of the drill, the land portion of the two edge portions having a top face joined to the central face of the central edge portion and curved in a direction to give a large area to the central face; a method of grinding the drill with the outer periphery and a side surface of a rotary grinder; and a drill grinding apparatus for practicing the method comprising a holding frame for reciprocatingly moving the drill axially thereof, means for rotating the drill, a disklike rotary grinder, and posture changing means for altering the angle between the grinding porti

Abstract: A drill construction to overcome the problem of high speed (>5000 rpm), high feed rate (>200 inches/minute) chip removal in deep hole drilling of nonferrous workpieces, comprising: (a) a shank for receiving rotary power, (b) an elongate bit extending from such shank coaxially aligned therewith and having a continuous single spiral land occupying one quadrant or less of said bit cross-section with a single spiral flute surrounding said land; (c) a cutting end portion extending integrally from said bit, said end portion having a conically-shaped end surface interrupted by diametrically opposed flutes, one of said flutes being a continuation of the bit flute thereby to define cutting edges, said edges further being defined by arcuate indentations resulting in a plurality of cusps to assist in breaking chips as they are formed; and (d) channels for conducting high pressure (>800 psi) fluid for cooling the bit, end portion, and chips during drilling and for hydrodynamically forcing the broken chips along

Abstract: A twist drill with a novel cutting and configuration is provided that has the center cutting capability of a two flute drill combined with the stability and accuracy of a four flute drill. The drill has four flutes and four lands, but only to complete cutting edges. The two complete cutting edges are formed by two complete lead facets that run all the way to the center axis of the drill, thereby also forming two chisel edges. The other two cutting edges terminate short of the center axis of the drill, each stopping at an intermediate gash located to either side of the chisel edges. The intermediate gashes interconnect the chip removal gashes that serve the four cutting edges, joining them in two pairs. A coolant passage exits each intermediate gash, near the chisel edges. Thus, as the drill center cuts, the chisel edge chips have a clear exit path into the intermediate gash and then out to one of the other chip removal gashes.

Abstract: A cutting tool in the form of a drill bit or end-milling tool has an elongated body formed with at least one cutting edge defined by a flank of a flute running primarily along a rotation axis of the body and having leading and trailing flanks one of which is formed with wavelike and spaced projections and recesses. The depth of these grooves and, hence, the height of the projections increases toward the end cutting edge to break up chips.

Abstract: Disclosed is a bit which can be cut both axially and laterally, and which is especially useful to cut an access opening in a sheetrock panel covering an electrical outlet box. The bit self-guides itself laterally around the periphery of the outlet box so that the opening will correspond to the shape of the box. The configuration of the bit permits it to be made in an unusually small diameter so as to minimize the width of the slot it cuts.

Abstract: A cutting tool such as a body drill has a cylindrical shank portion and a body section connected to the shank portion. The twist section terminates at a cutting end. A pair of flutes are formed in the body section, defining a land therebetween. The land includes a narrow margin having a width between 0.015 and 0.025 inches. The land also has a body clearance of a diameter less than that of the margins. The flutes terminate at flute faces at the cutting end. The flute faces are disposed parallel to each other at a zero degree rake angle. The narrow margin aspect of the invention could also be applied to a counterbore or spotface.

Abstract: The drill bit for producing a cylindrical drilled hole, especially in concrete, has a shank and a drilling head at one end of the shank provided with at least one helically extending drilling dust groove. At least two bulb-like shank enlargements (6,7) are provided on the shank (5) arranged in succession axially. Each of the shank enlargements (6,7) has the same maximum diameter and the drilling head has a drilling head diameter which is at least as great as the maximum diameter of the shank enlargements (6,7). Advantageously two drilling dust grooves with semicircular cross sections are provided on the shank displaced from each other radially by about 180.degree. to form a cross member with cutting edges on the drilling dust grooves.

Abstract: The subject of the invention is wood industrial drilling cutting tool for preparing holes mainly in wood and in the like sort, which holes can be used as blind holes for fastening together wooden constructions, furniture, toys etc. and which has one or more swarf-leading surface which is situated behind one or more main cutting edge which is continuously rising and reach the backside of the drilling body.The essence of the invention is that the swarf-leading surface is concave-courved seeing from the direction of bore rod, further, as a continuation of the swarf-leading surfaces a swarf-lifting spiral is formed on the bore rod.

Abstract: A twist drill includes a cylindrical body having an axis of rotation therethrough and having a forward end which contacts a workpiece. The body has a spiral flute formed in an outer peripheral surface thereof so as to extend spirally along a length thereof to the forward end and a land disposed adjacent to the flute. The flute has a first wall facing in the direction of rotation of the body and a second wall extending from an inner end of the first wall to the outer periphery of the body. The first wall terminates at the forward end in a first cutting lip having a radially outermost end disposed on the outer periphery of the body. The second wall is concavely shaped when viewed from the forward end and formed so that, assuming a first line extending from the outermost end perpendicular to a second line which connects the outermost end and the axis of the body, the maximum distance between the first line and the second wall is set to range between 0.45D and 0.65D, wherein D is a diameter of the body.

Abstract: A drill, which is excellent in sharpness and strength, capable of preventing burrs at an exit of a machined bore and of suppressing an excessive enlargement of the machined bore size, and is low in manufacturing costs, and easy te re-grind.A rake face (30) is provided to improve sharpness of a single chisel edge (3) formed between the tip of the drill and a first main cutting edge (1), and a non-chisel-edge-forming portion (B.sub.1 OB.sub.2) is provided between the drill tip end and a second main cutting edge (2) to improve strength of the drill.

Abstract: A drill screw is composed of a drill portion on a tip of the drill screw, a threaded portion succeeding to the drill portion and a head succeeding to the threaded portion whereby a ridge on the threaded portion threads into an inside wall of a hole the drill portion drills through a punctured object. The drill screw has cutting edges leading from both ends of a chisel positioned at the center of the tip of the drill screw. Each of the cutting edges forms an arc curving to a head side in an axial direction of the drill screw. Also, a shape of each of the cutting edges forms an arc curving to a back in a rotational direction of the drill screw.

Abstract: Method of making and tool bit construction; the bit has a diametrical blade implant of a two-phase material: a main phase of cemented carbine with diffusion bonded cubic boron nitride insert phases placed at high stress corners of such blade, limited strictly to the radial cutting zone of the bit without penetrating the centering zone.

Abstract: Disclosed is a spotweld removal tool adapted for removing spotwelds which join two or more layers of sheet metal to thereby free the sheet metal layers from one another. The spotweld removal tool comprises a split point twist drill having a central cutting tip (38) having leading edges (44 and 46) and defined by flared walls (56 and 58), recessed surfaces (64 and 66) adjoining the flared walls and peripheral cutting flats (40 and 42).

Abstract: The invention relates to the cutting tools for machining of holes.The claimed drill has helical chip flutes wherein the leading (5) and flank (8) surfaces and their mating surface (10) represent, each, a part of the circular helical surface.

Abstract: The brazing seams that attach cutting edge wear inserts on a drill are protected against wear and erosion. The inserts are deliberately differentially sized so that the points where the brazing seams that attach them intersect the cutting edges are differentially spaced from the drill center line. Then, a notch is cut into each cutting edge just wide and deep enough to prevent the brazing seam from contacting the cut. Cutting is still complete, despite the notches, since they do not overlap.

Abstract: The inserts and pockets in an inserted drill are provided with differing curvatures on their arcuate back edges. Consequently, when the insert is aligned in the pocket, a crescent shaped, instead of annular, gap is created, with minimal or no thickness at the outboard ends. Very little braze seam is thus exposed to erosion at the cutting edge, but the braze seam is as strong or stronger than conventionally. It is also easier to maintain the desired thickness of the braze seam during manufacture.

Abstract: For drilling a hole and machining at least its opening end without changing tools, a through-hole is drilled using a special tool, and then the same tool is moved sideways by means of a special chuck which guides the tool during machining of the drilled hole. The chuck has a locking means which when engaged holds it in a drilling position and which when disengaged allows sideways motion of a tool mounted in the chuck. The longitudinal section of the tool used, to be located within the hole during the machining operation, is situated within a curved surface having a radius just as great as that of the drill and having its center of curvature on the line about which the tool rotates during drilling.

Abstract: A twist drill for deep hole drilling comprises a cutting portion, margins (2) and helical flutes (3) designed for chip removal. The front-end wall (4) of the helical flute (3) comprises two conjugate sections (7, 8). The first section (7) intersecting with the margin (2) forms with the generatrix of the twist drill outer cylindrical surface an angle (.psi.) which is smaller than 90.degree.. The angle (.delta.) of inclination of the tangent at any point of the second sections (8) of the front-end wall (4), to the generatrix (9) of the twist drill outer cylindrical surface is selected proceeding from the relationship:125.degree.>.delta.>(57.degree.-.omega.).multidot.K+90.degree.,where: .omega. is the angle of helix of the helical flute (3) relative to the twist drill axis at the point under consideration.K=1.4-2.1.

Abstract: A twist drill having a longitudinal axis, a shank portion sized and shaped to be grasped by a twisting tool, and a barrel portion for cutting a workpiece. The barrel portion has a number of flutes formed therein spiraling about the axis and terminating at a point end of the barrel portion. The point end has a number of point surfaces including an inner flank surface, an outer flank surface, a groove surface positioned between the inner and outer flank surfaces and a split surface. The inner flank surface extends from the center of the point end to the inner extent of the groove surface and the outer flank surface extends from the outer diameter of the point end to the outer extent of the groove surface.

Abstract: A drill having a shank formed with helical or straight flutes for discharging chips therethrough and a pair of cutting edges formed at one end of the shank and extending continuously from the center of rotation of the drill to the periphery thereof. Each of the flutes is defined by a wall which is positioned rearward with respect to the direction of rotation of the drill and against which a flat plate portion of the chip formed by the portion of the cutting edge on the peripheral side is to be pressed, and by a wall positioned forward with respect to the direction for a side edge portion of the chip to come into contact with. The forward wall is inclined with respect to the rearward wall so as to prevent the chip from curling in its entirety. The drill is given improved rigidity and adapted to discharge chips as broken into fragments of suitable length.

Abstract: A body reaming tool for body work which can be used with a conventional drill to remove spot welds during automotive body repairs. A rigid shank coaxial with the longitudinal axis of the tool is fitted within the conventional chuck of a suitable electric hand drill. This increased diameter section is integral with the shank, and it includes an internal bore which coaxially receives twist drill bit used as a pilot. A conventional machine screw is employed in the counterbore section to lock the drill bit in place. The counterbore terminates in a plurality of fluted cutting teeth of a special configuration for quickly removing the metal, while preventing the metal from burring or otherwise interfering with subsequent part separation. Each of the cutting teeth terminate in a leading point which initially engages metal and the body part to be removed. A plurality of spiraling flutes are defined between the cutting teeth.

Abstract: A twist drill includes a cylindrical body having an axis of rotation therethrough and having a forward end which contacts a workpiece. The body has a spiral flute formed in an outer peripheral surface thereof so as to extend spirally along a length thereof to the forward end and a land disposed adjacent to the flute. The flute had a first wall facing in the direction of rotation of the body and a second wall extending from an inner end of the first wall to the outer periphery of the body. The first wall terminates at the forward end in a first cutting lip having a radially outermost end disposed on the outer periphery of the body. The second wall is concavely shaped when viewed from the forward end and formed so that, assuming a first line extending from the outermost end perpendicular to a second line which connects the outermost end and the axis of the body, the maximum distance between the first line and the second wall is set to range between 0.45D and 0.65D, wherein D is a diameter of the body.

Abstract: A drill having a shank formed with helical or straight flutes for discharging chips therethrough and a pair of cutting edges formed at one end of the shank and extending continuously from the center of rotation of the drill to the periphery thereof. Each of the flutes is defined by a wall which is positioned rearward with respect to the direction of rotation of the drill and against which a flat plate portion of the chip formed by the portion of the cutting edge on the peripheral side is to be pressed, and by a wall positioned forward with respect to the direction for a side edge portion of the chip to come into contact with. The forward wall is inclined with respect to the rearward wall so as to prevent the chip from curling in its entirety. The drill is given improved rigidity and adapted to discharge chips as broken into fragments of suitable length.

Abstract: A drilling tool, in particular for use in axially striking drive machines for drilling in rock, concrete or the like, which drilling tool is designed from both a vibration point of view by varying the abrupt changes in cross-section and from a drilling point of view by optimising the transport of the drilling dust. In order to arrange, from a vibration point of view, the abrupt changes in cross section, caused by the flute webs, in asymmetrically arranged axial positions, the inclination of the conveying flute constantly changes its size within a lead. Furthermore, the radial, tangential and axial force vector which acts on the drilling dust constantly changes its size, the radial force vector also changing its direction. In this way, the drilling dust is subjected to a constantly changing acceleration.

Abstract: A self-centering twist drill bit 20 is formed with a "fishtail" cutting section 32 having major cutting lips 72 and 74 on a working end 26 thereof at a point angle of 190.degree.. Tip relief surfaces 76 and 78 trail cutting lips 72 and 74. A pilot tip 38 on the working end 26 extends axially from the "fishtail" cutting section 32 and is formed with a split point having leading cutting edges 40 and 42 and minor cutting lips 46 and 48. Outer surfaces 58 and 60 of pilot tip 38 are each formed with a radial relief and a back taper and joins with cutting section 32 along fillets 92 and 100 which are also radially relieved.

Abstract: A drill for chipforming machining comprising a drill body (11), two cutting inserts (12, 13) and screws (14, 15). The cutting inserts are screwed to cutting insert sites (18, 19) in the axially forward end of the drill (10). The screws force the cutting inserts radially outwardly during tightening until a shoulder (28) at the lower side of each cutting insert abuts against a vertical support surface (22) on the drill body (11). The cutting inserts are tangentially mounted, i.e. they have holes for accomodating the screws, which terminates in the chip surfaces of the cutting inserts.

Abstract: A cutting tool for forming an opening in an object, such a steel belted tire or the like, is disclosed. The cutting tool is provided with a relatively small number of first helical grooves in its body portion, and a relatively large number of second helical grooves. The first and second sets of grooves are oriented in opposite directions relative to the longitudinal axis of the cutting tool. The tool so constructed is durable and capable of providing quick and clean operation in forming an opening in the said object.

Abstract: A drill for metal working comprises a drill body and a replaceable drill tip. The drill tip carries cutting elements and is releasably fastened to the drill body by means of fasteners which are provided on opposite sides of the centerline of the drill. A rear surface of the drill tip is provided with a central and at least partially conical, recess which is intended to receive a central tap extending forwardly from a mainly planar front surface of the drill body in order to center the drill tip in relation to the drill body. The tap engages the partially conical recess, and includes an elastic portion enabling the tap to yield axially.

Abstract: A drill/reamer bit has a drill portion formed by cutting edges at the end of a plurality of flutes. A reamer portion is contiguous with the drill portion and includes a first relief formed on each flute surface disposed at a predetermined angle with respect to the flute surface to form a first reamer cutting edge. A second relief is formed contiguous with the first face on each reamer portion and is disposed at a second angle, less than the first angle with respect to the flute surface. Preferably, the angle of the first reamer relief is substantially 30.degree. and the angle of the second reamer relief is substantially 10.degree..

Abstract: A tool in the form of a tapering borer or reamer has cutting portions adjacent the body of the tool with chip-receiving grooves therebetween, arranged alternately around the periphery of the tool. The cutting portions and the grooves may be of a helical configuration or may extend in a straight configuration parallel to the longitudinal axis of the tool. Each cutting portion has a cutting face and a relief face which intersect at a cutting edge. The cutting face defines a rake angle with respect to a first reference plane while the relief face defines a relief angle with respect to a second reference plane which is normal to the first reference plane.

Abstract: A rock drill for rotary and/or percussive stress, in particular for use in percussion or hammer drilling machines, is proposed, which by its geometrical design makes improved efficiency and simplified production possible. For this purpose, the feed spiral 5 is designed alternately with horizontal feed sections 8,8' with a 0.degree. pitch, and adjoining lead sections 9,9', the respective feed sections assuming an angle of rotation of 90.degree. on the drilling tool.

Abstract: A two-flute drill bit includes two drill webs each provided with a cutting lip. The cutting lips are unequally angularly spaced from each other and the smaller one of two pitch angles included between two cutting lips is preferably 160.degree.. One of the webs has two peripheral margin lands spaced from each other whereby a three-point guidance of the drill bit is obtained.

Abstract: The invention is a split-point twist drill for use in drilling holes in sandwich structures composed of a combination of organic matrix composite, titanium and steel. The drill (20) preferably has a web thickness (50) prior to splitting of between 23 and 27 percent of the drill diameter, a point angle (60) between 132 and 138 degrees, a web taper from the point to flute run out between 0.015 to 0.020 inch per inch, a chisel-edge angle (44) between 115 and 121 degrees and a splitting angle (70) between 127 and 137 degrees. Further important dimensions are a helix angle (24) of between 28 and 32 degrees and a lip relief angle (62) of between 10 and 14 degrees. Additional important splitting dimensions are a positive notch rake angle (74) of between 5 and 10 degrees, and an angle of the notch (72) to the drill axis between 32 and 38 degrees.

Abstract: A rock drill for rotary and percussive stressing exhibits equally good or improved transport characteristics of driling dust for a smaller transport groove as compared with prior rock drills. In order to achieve this, a main transport groove having longitudinal profiles is formed, with an interrupted secondary transport groove integrated in the main transport groove, the transport ribs of which exhibit a greater angle of twist than the angle of twist of the main transport groove.

Abstract: Disclosed is a drill for drilling thin plates and which has a pair of major cutting edges each including an inner major cutting edge diagonally extending in an inner portion of the tip so as to form a protrusive leading part, and an outer major cutting edge radially extending in the tip, a chisel edge formed at the junction of the inner major cutting edges, and continuous flanks formed behind the inner major edges and the outer major cutting edges, respectively. The diameter of the leading part formed by the inner major cutting edges is in the range of 40 to 50% of the drill diameter, the point angle formed between the inner major cutting edges is in the range of 100.degree. to 115.degree., the outer corner angle formed between the outer major cutting edge and a plane perpendicular to the axis of the drill is in the range of 4.degree. to 10.degree., and no margin is formed in the circumference of the tip.

Abstract: A coupling between a tool head and a tool support exhibits, for rough positioning, a holding fixture pin connection. By at least one fastening bolt running in the axial direction of the tool support, the tool head is braced against the tool support. In doing so the fastening bolt engages through a first screw coupling with the tool head and through a second screw coupling with the tool support. The first and second screw couplings exhibit synchronized threads of differing pitch so that, when tightening the fastening bolt, the tool support and the tool head are braced against each other in the axial direction. Further, the fastening bolt exhibits a centering section which, in the assembled state of the coupling, centers the tool head relative to the tool support. The fastening bolt, in the assembled state of the coupling, is received in its entirety in the inside of the unit formed by the tool support and the tool head and is accessible only through a borehole.

Abstract: A deburring drill bit having a shank, an elongated shaft, a drill bit head having forward drilling surfaces formed in the head, and rearward deburring surfaces formed behind said forward drilling surfaces, whereby drilling and deburring can be performed in a single operation, the drilling surfaces having a first longitudinal axis and the deburring surfaces having a second longitudinal axis not coincident with said first longitudinal axis.

Abstract: A drill includes a plurality of lips with enlarged portions at one end defining heads therefore. The heads form frusto-conical surfaces and cutting edges extend from the frusto-conical surfaces to remove chips. The cutting edges are limited in size with respect to the frusto-conical surfaces to control the removal of chips and a pocket behind each head readily receives the shavings to convey the latter away from the one end.

Abstract: A twist drill having a longitudinal axis and major flanks ground by helical face grinding by means of a grinding wheel having a grinding face perpendicular to its axis of rotation and a circumferential profile, each major flank terminating in a cutting edge and having a surface which defines a clearance angle relative to the cutting edge wherein: the drill has an outer diameter and a central solid core having a thickness equal to 25% to 40% of the outer diameter; and each major flank is ground by a grinding operation performed by rotating the grinding wheel while its grinding face forms the major flank, effecting angular movement of the drill about its longitudinal axis and relative to the axis of rotation of the grinding wheel, effecting relative radial movement between the grinding wheel and the drill in the direction perpendicular to the drill axis and away from the axis of rotation of the grinding wheel, and effecting axial movement of the drill along its longitudinal axis toward the grinding wheel in a p

Abstract: A one-piece rotary drill or end milling cutter is an extruded product made of sintered hard metal. The front end portion of its shank has one or more cutting edges and its rear end portion tapers in a direction away from the front end portion and is receivable with friction in a complementary conical socket of a rotary holder. The shank has one or more longitudinally extending coolant holes with a circular or triangular cross-sectional outline, and such hole or holes are formed in the course of the extruding step. The periperhal surface of the shank has one or more longitudinally extending chip evacuating grooves, and those portions of the grooves which are formed in the rear end portion of the shank contain fillers of bondable plastic material or solder.

Abstract: A drilling tool which has at least one helical fluid flow channel at its interior, is composed of a hard metal core having an exterior surface and a hard metal tubular casing having an interior surface. The casing encloses the core with their surfaces in firm contact so that the core and casing form a composite body. Each channel is formed as a groove in the surface of the core or casing.

Abstract: There is disclosed a twist drill particularly adapted for drilling plastics and composite materials having a sharp point angle, typically 85.degree. to 95.degree., and a very low lip relief angle, typically 2.degree. to 3.degree.; the relief surfaces are broad, though not unusually so, and may each subtend an angle of 40.degree. to 60.degree. about the drill longitudinal axis. A two-flute drill is shown, but the structure may be modified to provide three or more flutes. Land width, helix angle, and other attributes of the twist drill are generally similar to most common varieties of twist drills for steel, wood, or other uses in drill presses or hand drills.

Abstract: A self-drilling screw having a head at one end and a forged drilling end configuration at the other. The drilling end configuration comprises a pair of longitudinally extending flutes which are separated by land portions and which extend through a tapered tip end to form two cutting edges. The forging operation is performed in such a way as to promote complete formation of the tip end and that may be achieved by inhibiting material flow away from that tip end or by promoting extrusion of material towards the tip end. The drilling end portion of the screw is of elliptical cross section having a minor axis in the region of 60 to 80% of the major axis, and a fillet is formed in the base of each flute at the tip end portion of the flute. Each fillet has a flat surface arranged generally parallel to the screw axis and angularly relative to the ajacent cutting edge of the tip end.

Abstract: A helically fluted twist drill apparatus in which offset, opposed veins of sintered abrasive particulate, such as diamond, are embedded within a drill blank made of a less abrasive material such as carbide. The non-aligned veins of abrasive material, in one embodiment, themselves intersect through juxtapositioning adjacent the point and web of the drill, and in another embodiment, rely upon the interpositioning of a third intermediate vein which, in turn, intersects at least part of both the first and second nonintersecting veins, to describe a more economical and effective highly abrasive material region at the drill point and web locations.

Abstract: A four surface point type drill has its primary clearance faces configured so that their circumferential width decreases as the longitudinal axis of the drill is approached. The trailing edge and cutting edge of the primary clearance face surfaces substantially intersect each other at a point where they both intersect the opposite ends of the chisel edge of the drill point. The chisel edge itself is totally defined by a line formed by the intersection of the two secondary clearance face surfaces of the drill point. This new improved drill point geometry permits the use of reduced primary and secondary clearance face relief angles at the drill point which improves the structural integrity of the cutting edge of the drill and hence reduces chipping at the cutting edge.