Abstract: A tool shank for use with a cutting insert in a rotary cutting tool includes a body having, and adapted to be rotated about, a central longitudinal tool axis, the body having a tip portion structured to receive at least a portion of the cutting insert therein. The shank also includes a pair of chip flutes formed in the body and a pair of recesses, each recess bordering a respective chip flute. Each recess includes a rim portion extending perpendicular to the tool axis and a bearing surface extending at an incline relative to the tool axis. Each rim portion is adapted to engage a corresponding surface on the cutting insert. Each bearing surface is adapted to engage a corresponding bearing surface on the cutting insert in a manner such that the cutting insert is pulled against the body when the rotary cutting tool is rotated about the tool axis.

Abstract: A rotary cutting tool includes a generally cylindrical body having a first end, a second end and a longitudinal axis therebetween. A mounting portion is disposed about the first end, a head portion having an outer diameter is disposed about the second end, and a body relief portion having an outer diameter less than the head portion is disposed therebetween. The head portion is structured to engage and cut a workpiece. A number of flutes extend from the second end of the cylindrical body along the head portion and along at least a portion of the body relief portion. The head portion includes a number of margin relief surfaces, each disposed between adjacent flutes and inset a distance from the outer diameter of the head portion and extending from the second end of the cylindrical body and terminating at a margin seal within the head portion.

Abstract: A drill bit with high performance for chip removal. The drill bit comprises a cutting tip and a drill body. The cutting tip comprises a chisel edge, a back edge, a cutting edge groove and a rear rib. The cutting edge groove is a circular groove having meniscus shape. A primary cutting surface interposed between the cutting edge groove and the back edge has a trapezoidal or triangular shape. Grinding the rear rib forms a quadratic rear plane. The quadratic rear plane crossing with the chisel edge and the cutting edge groove defines a cutting edge groove plane. The drill bit has three tips and seven cutting edges. A drill bit according to the present invention provides a significant improvement in cutting performance over known twist drill bit in the prior art.

Abstract: The invention proposes a drill bit (1) leaving at least one main cutting edge (3, 3?) and at least one center cutting edge (15, 15?), wherein the drill bit (1) comprises a longitudinal axis (13), and wherein the at least one main cutting edge (3, 3?) and the at least one center cutting edge (15, 15?) are each assigned a rake face (7, 7?, 11, 11?). The drill bit (1) is characterized in that the rake face (11, 11?) assigned to the at least one center cutting edge (15, 15?) has at least two part faces (19, 19?; 21, 21?) which—as seen as perpendicular to the longitudinal axis (13) of the drill bit (1)—form an obtuse angle with one another, so that the at least one center cutting edge (15, 15?) comprises at least two part cutting edges (23, 23?; 25, 25?).

Abstract: A drilling tool of the loose top type includes a basic body having two bendable branches having inner support surfaces that are resiliently pressable against side contact surfaces of a replaceable loose top. The mounting of the loose top is affected by turning-in from an initial position to an operative end position. An abutting edge along each side contact surface then bends out the branches and subjects the branches to a spring force that reaches a maximum in a dead position so as to then decrease somewhat up to the operative end position. During the final phase of the rotary motion, the operator obtains, in a tactile and/or auditory way, confirmation of the loose top indeed reaching its operative end position.

Abstract: A bit exchangeable drill includes a detachable cutting head at the tip of a drill body, and the cutting head includes a cutting edge extending linearly from a rotation center to a radial outer end in axial end view, and a helical flute. At a rake face continuous with the cutting edge, a thinning face inclined relative to the rotation axis and rendering an axial rake angle of the cutting edge negative is formed entirely from a radial inner end to a radial outer end of the cutting edge.

Abstract: A twist drill for drilling composite materials includes a shank; a drill body; a drill tip having a cutting edge, a chisel edge, and a secondary chisel edge, wherein the secondary chisel angle of the drill tip is 145° to 165 and the point angle is 70° to 100°; and a flute extending from the drill tip to the drill body. The flute has a constant helix, and the helix angle of the flute being selected from the range 45° to 55°. A method of drilling a composite material comprising fibres uses the twist drill of the present embodiment. Suitably, the composite material is carbon fibre reinforced plastic or glass fibre reinforced plastic, and optionally being a laminate material such that the method comprises stack drilling. Embodiments achieve a combination of good hole quality, good tool life and good hole size spread.

Abstract: A drilling tool for machine tools has a drill body and a cutting head arranged on the front face of the drill body. The drill body has at least two chip flutes, which are delimited at their flanks by ribs and at least one of which is spirally curved. Arranged in the ribs of the drill body are coolant channels, which have an outlet opening at the end of the drill body on the cutting head side. A special feature is that the outlet openings are arranged within each one of the chip flutes and communicate with one of the coolant channels arranged in the ribs by way of a straight channel endpiece.

Abstract: A combination drill bit for use in both hand held drills and stationary drill presses has a shanking end, a working end and a helical flute portion between the shanking and working ends. The helical portion has a helix length (L) of L = ( D × ? tan ? ? ? ) . The drill bit has a core that is tapered from the working end to the shanking end. A web thickness length at the working end is 10% to 35% of the diameter and the thickness length at the junction of the shanking end is 70% to 90% of the diameter. The drill bit is manufactured from a high speed steel including at least 5% by weight of cobalt.

Abstract: A tool bit providing a combined drill bit and milling bit is disclosed herein. The tool bit in one embodiment includes a working section having a longitudinally extending central axis, an O-flute extending along the working section, and a tooth formed at a tip portion of the working section, the tooth offset from the central axis.

Abstract: A tool bit (1) ready for use consists of a sintered material. It has a longitudinal axis (3). At least one swarf chamber (4) spaced from the longitudinal axis (3) land extending along the longitudinal axis (3) is formed in the tool bit (1). The tool bit (1) has at least one cutting edge (8, 10), which is formed in the tool bit (1) by grinding the already sintered tool bit (1), adjoining the swarf chamber (4). According to the invention the swarf chamber (4) is ground only partly and is otherwise unground.

Abstract: A cutting tool having a shaft with a longitudinal axis, wherein the cutting tool includes a first flute extending about the longitudinal shaft along a helix angle and a first cutting edge adjacent the first flute. The cutting tool also includes a second flute extending about the longitudinal shaft along a helix angle and a second cutting edge adjacent a second flute. The cutting tool further includes a third flute extending about the longitudinal shaft along a helix angle and a third cutting edge adjacent the third flute. The first cutting edge, the second cutting edge, and the third cutting edge are unequally angularly spaced from each other.

Abstract: The invention relates to a rock drill comprising an insertion portion, a flute adjoined to the insertion portion, and a head portion adjoined to the flute, wherein the flute is of at least double-spiral configuration and correspondingly has at least two substantially spiral discharge grooves, to which respectively two substantially spiral flute webs forming the lateral groove walls are assigned. It is proposed that a constant spiral pitch is assigned to the first discharge groove, inclusive of the lateral groove walls thereof, along the drill longitudinal axis, and that at least one of the two flute webs assigned to the first discharge groove has or have along the drill longitudinal axis, at least in sections, a web spine width which changes, in particular, alternately.

Abstract: Embodiments of the disclosure provide a drill bit including a drill bit body having a central axis. A first cutting edge is disposed on the drill bit body at a first radial distance from the central axis as measured within a plane normal to the central axis. And a second cutting edge is disposed on the drill bit body at a second radial distance from the central axis as measured from within the plane. The first radial distance is less than the second radial distance.

Abstract: A rotatable tool for chip removing machining, including a basic body having front and rear ends between which a first center axis (C1) extends around which the basic body is rotatable, and a loose top having front and rear ends between which a second center axis (C2) extends. The front end of the basic body includes a jaw which is delimited by two torque-transferring drivers and an intermediate bottom in which a part of the loose top is receivable, and a center hole that mouths in the bottom of the jaw and has a hole wall which extends axially inside the basic body and in which a threaded hole mouths for a screw to co-operate with a centering pin that protrudes axially rearward from the loose top, the centering pin being insertable into the center hole. The centering pin has a cross-sectional area that is less than a cross-sectional area of the center hole.

Abstract: A twist drill includes a drill body having a chip flute extending a distance along the drill body. The chip flute has a leading edge and a run-out edge running along the chip flute. The run-out edge is disposed behind the leading edge in a direction of rotation of the twist drill. The chip flute, viewed cross-sectionally in a direction perpendicular to the longitudinal axis, includes a first wall portion and a second wall portion. The first wall portion extends along a curve between the run-out edge and the second wall portion. The second wall portion extends in a straight line from between the leading edge and the first wall portion. The first wall portion and the second wall portion are disposed adjoining one another and together define a J-shaped cross-sectional profile perpendicular to the longitudinal axis.

Abstract: A drill having end-face major surfaces, contiguous faces descending from the major cutting edges and flanks contiguous to the major cutting edges. Center cutting edges are formed by end-face taperings. A chisel cutting edge is between the center cutting edges. Shapes of the cutting edges are disclosed. First ones of the flanks are angled to create an outward apex angle so that the major cutting edges and the center cutting edges run at a constant taper angle.

Abstract: A drill bit having features rendering it particularly effective in cutting holes in carboresin laminates of the type used in the aircraft industry. A pair of diametrically opposite lands slope radially inward at the working end of the bit to a pair of cutting edges disposed at an obtuse angle to one another and forming an efficient cutting tip. Notches with sloping ramps adjacent the cutting edges efficiently convey cut material to adjacent flutes. The lands curve radially inward between their full diameter portion and their cutting tips and the junction of the curved portion and the constant diameter portion of the lands is machined to provide a more gradual transition.

Abstract: [Problem] To provide a drill which enables a great reduction in cutting resistance and easy performance of a drilling operation by human power using a hand drill, a drilling machine, or the like. [Solution] A drill has two cutting edges formed symmetrically with respect to a rotation axis, and is subjected to thinning at the tip thereof. The cutting edge is configured from a thinned cutting edge (1) which extends in a shape including a curved line from a chisel edge to the outer peripheral side of the drill, and a main cutting edge (2) which extends from the end of the thinned cutting edge to the outer peripheral end of the drill when viewed from the tip side of the drill, and a thinned surface formed by the thinned cutting edge is formed into an approximately parabolic shape inclined in a drill axis direction when viewed from the front side of the drill.

Abstract: A drill bit for drilling having at least two cutting edges, each with two cutting portions and a non-cutting portion between the two cutting portions. The abstract of the disclosure is submitted herewith as required by 37 C.F.R. §1.72(b). As stated in 37 C.F.R. §1.72(b): A brief abstract of the technical disclosure in the specification must commence on a separate sheet, preferably following the claims, under the heading “Abstract of the Disclosure.” The purpose of the abstract is to enable the Patent and Trademark Office and the public generally to determine quickly from a cursory inspection the nature and gist of the technical disclosure. The abstract shall not be used for interpreting the scope of the claims. Therefore, any statements made relating to the abstract are not intended to limit the claims in any manner and should not be interpreted as limiting the claims in any manner.

Abstract: A drill bit for drilling holes in wood or the like has a spade cutting element, a thick elongate shaft and a shank adapted to be inserted into an SDS drill chuck. In a preferred embodiment, the shaft is provided with one or more ridges extending helically along most of its length, to strengthen and stiffen the shaft and to direct drilling debris away from the cutting element. The shaft has a diameter greater than or equal to that of the shank. The drill bit may be installed in and removed from the drill chuck more rapidly than conventional wood bits, is more robust and is more convenient and reliable in use.

Abstract: A flute spread angle ? in a drill axis-perpendicular section of a spiral flute is defined, a region of the flute taking part in chip treatment is formed along a first circle along an cutting edge of a concave curve and a second circle inscribed in this circle, both of the first circle and the second circle are circumscribed on a third circle expressing the web thickness, the radius R of the first circle and the radius R1 of the second circle are in the range of 0.40 D to 0.70 D and in the range of 0.15 D to 0.30 D respectively, and a drill rotational direction front portion of the spiral flute is formed on the second circle to be closer to the drill center than a fourth circle having a diameter of 0.65 D.

Abstract: A metal-working twist drill is provided with inner cutting edges that form a point (18) having an angle, A, of 130°. An outer, peripheral, part of each cutting edge (55, 57) forms an outer cutting portion (59, 61). The outer cutting portions slope in the opposite direction to the corresponding inner cutting edges and form an angle B, of 3° with respect to a plane normal to the axis of rotation of the twist drill. The width of the outer cutting portion, D as measured at the cutting edge, is 10.5% of the diameter of the twist drill. The metal-working twist drill produces bores having a reduced exit burr height.

Abstract: A cutting tool has a tool shank and a replaceable cutting head resiliently secured to the tool shank by an interference fit between a male fixation member of the cutting head and a female fixation member of the tool shank. The male fixation member has a resilience slit. In each cross section of the cutting tool taken perpendicular to an axis of rotation of the cutting tool through mutual abutment regions, the cross sectional profiles of the mutual abutment regions are arcuate sectors.

Abstract: A twist drill includes a drill body having a chip flute extending a distance along the drill body. The chip flute has a leading edge and a run-out edge running along the chip flute. The run-out edge is disposed behind the leading edge in a direction of rotation of the twist drill. The chip flute, viewed cross-sectionally in a direction perpendicular to the longitudinal axis, includes a first wall portion and a second wall portion. The first wall portion extends along a curve between the run-out edge and the second wall portion. The second wall portion extends in a straight line from between the leading edge and the first wall portion. The first wall portion and the second wall portion are disposed adjoining one another and together define a J-shaped cross-sectional profile perpendicular to the longitudinal axis.

Abstract: A drill according to an embodiment of the present invention includes a body part and a cutting part with a cylinder-like shape. The cutting part includes two cutting edges located separately from each other at a front end portion of the cutting part, two flutes which are continuous with each of the two cutting edges and extend spirally toward a rear end portion of the cutting part, and a clearance which extends spirally from a side of the front end portion to a side of the rear end portion, and is recessed inward in reference to a periphery of the cutting part in a sectional view. The cutting part includes a first joining flute including at least one of the two flutes and the clearance being joined together. The first joining flute includes a bottom surface being outwardly protruding curve-like line in a sectional view. A method of manufacturing a machined product using the drill is also provided.

Abstract: The invention relates to a drilling tool comprising a clamping shaft and cutting element contiguous with said clamping shaft. The cutting element comprises at least one flute having a flute surface that has a concave cross-section. The at least one flute has a cut-in section in the chip-forming zone adjacent to the main cutting edge in the area of the flute front and/or the back segment to enlarge the flute cross-section.

Abstract: A rotatable tool for chip removing machining including a basic body and a loose top; the body includes two torque-transferring drivers and an intermediate bottom in which a rear coupling part of the loose top is receivable, and a center hole that mouths in the intermediate bottom. A centric pin is insertable into the center hole, and a screw is accessible from the outside of the basic body. The coupling part includes a pair of side contact surfaces which cooperate with a pair of side support surfaces on the drivers of the basic body for the transfer of torque and negative axial forces between the coupling part and the drivers.

Abstract: A self-drilling screw (10) has a thread-carrying shaft (11), a head (15) provided at one of its ends, and a drilling tip (12) provided at another of its ends, opposite the one end thereof, with the drilling tip (12) having first and second cutting edges (21, 22) and first and second chip channels (24, 25) associated with the first and second cutting edges (21, 22), respectively, beginning at first and second start points (26, 27) at the free end (14) of the drilling tip (12), and located on opposite first and second sides of the drilling tip (12), with the first and second start points (26, 27) being spaced from the center (Z) of the drilling tip (12) by a mean distance (X) corresponding to from 0.01 to 0.15 of the drilling tip diameter (D), and being spaced from each other by a maximum distance (Y) corresponding to from 0 to 0.8 of the mean distance (X).

Abstract: A rock drilling tool includes a drilling head provided with a cutting body and a helix arranged between the drilling head and a shaft. The cutting body extends continuously over a nominal diameter of the rock drilling tool and has an inner region configured as a centering tip and an outer region bordering the centering tip in the radial direction. The outer region is offset towards the rear in relation to the centering tip in the active direction of the rock drilling tool. The centering tip is configured as a pyramid or a truncated pyramid and has pyramidal edges with lateral surfaces located therebetween. At least one lateral surface of the centering tip is configured as a cavity.

Abstract: A drill is capable of forcibly aspirating and discharging chips to prevent environmental contamination as well as to simplify cleaning the chips. The drill has an intake hole and an opening formed therein so that the aspiration takes place through the intake hole and the chips generated in the cutting process can forcibly be aspirated from the opening. Because the chips can be discharged without using cutting fluid, the drill is useful for preventing environmental contamination. Moreover, as the chips are forcibly aspirated from the opening and discharged through the intake hole, the chips are not scattered around a workpiece under the cutting process and cleaning the chips can become simple and easy.

Abstract: A cutting bit for a pruning tool includes an elongate body having a first end and a second end. At least one flute extends at least part of a distance between the first end and the second end of the elongate body. A shank is located at the first end of the elongate body and is adapted for connection to an associated pruning tool. The second end of the elongate body defines a boring tip.

Abstract: A drill for making a hole within a workpiece has a body extending along a longitudinal axis, at least one flute extending along the body, and a drill point extending from the end of the body. The drill point has a periphery and is comprised of a chisel edge, a primary cutting edge extending inwardly from the periphery, a secondary cutting edge extending outwardly from the chisel edge, and a tertiary cutting edge connecting the primary cutting edge with the secondary cutting edge, wherein the tertiary cutting edge has a negative axial rake angle. A method for producing such a drill point is also disclosed wherein in one grinding pass a gash forms the axial rake angle of the secondary cutting edge, and in a separate grinding pass a portion of the secondary cutting edge is removed to produce a tertiary cutting edge having an axial rake angle that is negative.

Abstract: Rotatable multi-operation tool including replaceable cutting inserts of different types, and a basic body rotatable around a center axis with rear and front ends from which there is extending rearward an envelope surface in which at least one chip space is countersunk, which opens in the envelope surface and in the front end. A first cutting insert type is mounted in a first insert seat formed in one side surface of the chip space in the immediate vicinity of the front end and included in a cavity opening in the front end for the cutting insert to partly protrude axially forward from the front end. A second cutting insert type is mounted in a second insert seat formed in the same side surface as the first insert seat and situated axially behind the first insert seat and included in a cavity opening in a part of the envelope surface.

Abstract: An indexable drill includes an insert attachment seat and a chip discharging groove formed so as to extend from a leading end surface to a trailing end side of the drill in the direction of the axis of rotation and through which chips generated by the cutting insert are discharged, and in that a wall surface defining the chip discharging groove at least partly includes a smoothed surface with a surface roughness of at most 0.5 ?m in terms of arithmetic average roughness Ra, the wall surface of the chip discharging groove is partly formed on a thinned wall portion thinned by the central edge attachment seat and the outer peripheral edge attachment seat, and a crossing portion between the first wall surface and the second wall surface in the thinned wall portion is rounded.

Abstract: A drill in which a flute is formed from a point to a base end side of a body of the drill, on a side face to be rotated about an axis, a cutting edge is formed between a wall surface of the flute which faces a drill rotational direction side and a flank at the point of the body, and a thinned portion is provided to a web portion of the point. The cutting edge is formed in a convex arc shape with a curvature radius 0.25 to 1 times a drill diameter; a radial rake angle at an outer peripheral portion of the cutting edge is ?60 to ?15 degrees; a corner portion, closer to the center of the point, of the thinned portion is formed in an arc shape with a curvature radius of at least 0.1 mm and not greater than 0.05 times the drill diameter; and the drill includes three flutes and three cutting edges.

Abstract: A drilling tool includes at least two chip flutes and a chisel edge with a thinned region. The thinned region merges continuously into the chip flutes in such a way that the thinned region forms the end of the respective chip flute in the region of the chisel edge.

Abstract: The present invention is concerned with twist drills for drilling of composite materials such as carbon fibre reinforced plastic (CFRP) and glass fibre reinforced plastic (GFRP). The present invention proposes that a twist drill (2) is provided with a variable helix having a defined start and finish helix angle, in combination with primary and secondary relief angles such that the drill (2) is adapted to minimise thrust force, particularly when used for drilling fibre—containing composite materials and especially for hand drilling. Start and finish helix angles of 50° and 10°; 50° and 30°; and 30° and 10° have been shown to provide excellent cutting performance and exit hole quality. A large secondary chisel edge angle (24) has also been found to contribute to excellent performance with composite materials, including stack machining.

Abstract: A cutting tool insert and holder therefore, the drill insert having a helical geometry corresponding to helical flutes in a drill body holder which enable the drill tool assembly to more efficiently remove chips from a hole during operation, the drill insert comprising a drill insert body having a first end opposite a second end, a plurality of helical flutes formed in the drill insert body, a plurality of cutting edges formed at the interfaces of the plurality of helical flutes and the first end of the drill insert body, and an aperture formed in each helical flute.

Abstract: A rotary cutting tool that is composed of a tool shank with at least one chucking groove or chip flute and one exchangeable cutting insert. At the tip of the shank a recess for accommodating the cutting insert is provided. The tool shank, on its circumference, has a limb with a bearing surface that is inclined relative to the tool axis and that corresponds to a likewise inclined bearing surface on a wing of the cutting insert. The inclination of the bearing surfaces produces an axial force that retains the cutting insert on the tool shank.

Abstract: A rotatable multi-operation tool for chip removing machining, including a plurality of replaceable cutting inserts of different types, and a basic body that is rotatable around a center axis and includes a rear end and a front end from which there is extending rearward an envelope surface in which at least one chip space, delimited by two opposite side surfaces, is countersunk, which opens in the envelope surface and in the front end. A first cutting insert is mounted in a first insert seat that is formed in one side surface of the chip space and situated in the immediate vicinity of the front end and included in a cavity that opens in the front end for the cutting insert to partly protrude axially forward from the front end. A second cutting insert, of a type other than the first cutting insert, is mounted in a second insert seat, which is formed in the same side surface as the first insert seat and situated axially behind the first insert seat.

Abstract: A drilling/reaming tool includes a basic body which extends in a longitudinal direction. The basic body includes at least one end-side drilling major cutting edge, a main flute which is assigned to said drilling major cutting edge and is wound at a first helix angle, and a plurality of reaming cutting edges which are arranged circumferentially on the basic body and have in each case one reamer flute which is assigned to the respective reaming cutting edge and is wound at a second helix angle. The reaming cutting edges adjoin the at least one major cutting edge directly in the longitudinal direction. Each reamer flute is merged into the main flute.

Abstract: A drill body for chip removing machining, including a rotationally symmetrical envelope surface and front and rear ends between which a center axis extends, around which the envelope surface is rotatable in a predetermined direction of rotation. A head is formed in the front end that includes two cutting edges, each one of which includes a first part edge and a second part edge. The first part edge is included in a central tip part having a front end portion situated along the center axis. The second part edge extends between a peripheral end point positioned along the envelope surface and a radially inner end point where the second part edge transforms into the first part edge. The two first part edges converge at a positive nose angle (?) in an axially forward direction, and the two second part edges diverge at a negative angle (?) in the axially forward direction.

Abstract: A drill in which no positional shift on a drilled hole and no irregularities on an internal wall are formed. A torsion angle of a shaving discharge groove of a drill is set in the range of 30 degrees to 50 degrees. In this manner, a positional shift of a through hole to be drilled can be reduced. In addition, shavings of the drill are properly discharged, and thus, drilling is not precluded by the shavings. Therefore, a printed wiring board having excellent electric connectivity and reliability can be obtained.

Abstract: A twist drill having at least two cutting inserts at the tip each with its own J-shaped chip guiding flute and a method for the production thereof.

Abstract: Rotatable drilling tool has an insert top detachably connectable to a basic body and at least one chip flute. In each cross-section, each chip flute has a depth equal to the difference between the radius of a cutting circle and a radius of a greatest possible core circle centered on the longitudinal axis and tangential to a limiting curve of the respective chip flute. The basic body is divided longitudinally into a coupling segment, extending axially rearward from a coupling end, and a transportation segment that is situated axially behind the coupling segment, extends rearward toward a fixing end, and is longer than the coupling segment. Each chip flute extends through the coupling segment and the transportation segment. At least essentially the entire female part is situated in the coupling segment, and each chip flute has a smaller depth in the coupling segment than in the transportation segment.

Abstract: A bit for removing a broken fastener comprises a tip from which extend two or more notches separated by traction or biting surfaces formed from two-sided frusto-conically-shaped regions. The surfaces are bounded on one side by a nonlinear cutting edge and on the other side by a non-cutting edge and are configured to cut into the fastener when the bit is rotated in a direction opposite to the fastener's direction of engagement. Specific embodiments include configurations where the cutting edges extend at different angles with respect to the bit axis, where the biting surfaces comprise a plurality of serrations, and where the cutting edges are separated by flutes which spiral along a longitudinally extending periphery of the bit.

Abstract: A drill body for chip removing machining, including an envelope surface which is concentric with a center axis around which the drill body is rotatable, and transforms into a front end surface, and a front cutting edge adjacent to a chip flute which is countersunk in the envelope surface in the area in front of the cutting edge as viewed in the direction of rotation of the drill body and runs out into the front end surface. In the front part of the chip flute, a depression is formed, which includes two part surfaces extending at an obtuse angle (?) to each other, one of which forms a bottom surface in the depression, and the other of which faces the cutting edge and is in front of the cutting edge as viewed in the direction of rotation to form a stop face for a chip removed by the cutting edge.

Abstract: An object is to provide a drill for a composite material which can realize high-quality boring hardly causing burrs or delamination in boring of a member to be machined containing a fiber reinforced composite material at least partially.

Abstract: This invention has to do with a rotary twist drill of the type having a fluted cylindrical shank with a drill bit end having at least two cutting edges extending radially outwardly from the longitudinal axis of the drill. Cutting edges are formed by the intersection of the flutes with the drill point end and extend radially outwardly from the center of the drill body to the outer perimeter of the drill body. Gashes formed on the drill point end form innermost cutting edge portions which are symmetrical with one another about a point offset both horizontally and vertically from the axial centerline of the drill body so as to allow a positive cutting action at the centerline of the material to be removed.