Abstract: The invention relates to a drilling tool (11) for bores in solid material, comprising a drill shank (26) which has a radially inner indexable insert (13) at an inner chip space (21) and a radially outer indexable insert (14) at an outer chip space (22), the working areas of which indexable inserts (13, 14) overlap, the inner chip space (21) having a cover (36) which extends at least partly along the shank longitudinal axis (20), and the inner chip space (21) merging into the outer chip space (22), so that the chip discharge is effected via a common chip space (23) in the rear area (32) of the drilling tool (11).

Abstract: An end mill (10) has a cylindrical shank (12) with a longitudinal axis (22). Attached to the cylindrical shank (12) is a center flute (14) having a cutting edge (18) extending beyond the longitudinal axis (22). A non-center flute (16) is also attached to the cylindrical shank (12). The center flute (14) has a first rake angle (32) and the non-center flute (16) has a second rake angle (32) not equal to the first axial rake.

Abstract: A percussive blow assisted rotary drill includes an axially extending shank (1) with a leading end face (3) and an axially extending outside surface (2) containing a helically extending drilled material removal groove (4, 5). At least one hard metal cutting plate (6) extends across a diameter of the shank and has a base part fixed in a continuous groove (9) in the leading end face (3) of the shank (1). The base part (10) is reinforced by an outwardly extending projection (12) in at least one of its side surfaces extending across the shank diameter. Preferably, the projections forms a part of a circle and are centered between the opposite ends of the cutting plate. The continuous groove (9) has a recess in at least one of its side surfaces shaped to coincide with the shape of the outward projection (12) on the cutting plate. Accordingly, the base part (10) is secured in a positively locked manner and preferably is centered in the leading end face of the shank.

Abstract: A compost aerator and monitor which has a cylindrical helical screw, preferably with a sharpened first end. The diameter of the cylindrical helix and the tightness of the windings are selected so as, when the screw is inserted into a compost pile, to create a core of compost material that is sufficiently large to be cohesive and representative but not so large that the weight of the core will cause the core to fall from the screw when such screw is withdrawn from the compost pile. Attached to the second end of the screw is a handle with sufficient leverage to enable the screw to be turned rapidly and, consequently, rapidly introduced into a compost pile and to preclude the screw from rotating as the screw is withdrawn from the pile, thereby retaining the core of compost material. Optionally, either a traditional brace or a traditional power drill can replace the simple handle; and a shaft can be inserted between the screw and the handle or the brace.

Abstract: A self-centering indexable drill having cutting inserts disposed such that cutting forces on the inboard and outboard flutes of the drill body are substantially equal while boring a hole, thereby keeping the drill body substantially centered. The drill includes a drill body and a plurality of cutting inserts. The drill body includes a shank portion configured to be received by the spindle of a machine using the drill, a collar, and a fluted portion. The fluted portion of the drill body defines an inboard flute and an outboard flute. At least one cutting insert is releasably secured to each of the inboard and outboard flutes, with an equal number of cutting inserts carried by each. An insert pocket is defined by the drill for closely receiving each cutting insert such that the leading face of the cutting insert is substantially flush with the face of the flute.

Abstract: A tool for preparing a coaxial cable for termination includes a tool holder supporting an axially elongated cylindrical cutter and carrying a guide bushing for maintaining an end portion of a coaxial cable in coaxial alignment with the cutter as the cutter is rotated relative to the cable. A chamfer on the free end of the cutter defines the radially outer extent of a first cutting edge which removes core material contained within the metallic outer sheath of the cable. A coaxial bore extends through the cutter and receives the cable central conductor. A second cutting edge located near the free end of the cutter and partially defined by the cutter bore wall skives core material in close proximity to the surface of the central conductor. A third cutting edge spaced from the first and second edges strips material from the metallic sheath to expose an end portion of the conductor beyond the end of the sheath.

Abstract: Method of forming rotary drilling tools (1) for working on materials subject to brittle failure, such as drilling tools or hammer drilling equipment, includes shaping an axially extending conveying helix (3) in an axially extending tool blank (11) and forming the conveying helix (3) in a region between an axially extending cutting head region (4) at one end of the blank and an axially extending shank (2) at the other end of the blank. The cutting head region (4) is free of any conveying helix and has an axial extent of at least 10% of the maximum diameter (d) of the rotary drilling tool in the axially extending region of the conveying helix.

Abstract: The cutting end or head of a helically grooved drill bit is of generally hemispherical shape and has four cutting lips, two of which are disposed in end-to-end relationship at the point S of the bit. The cutting angle of the edge of each lip is evolutive, varying from 0.degree. at the point S to a value, determined experimentally in accordance with the material to be machined, at a position P at the intersection of the cutting edge with the end of the outer diameter d of the bit.

Abstract: A chip discharge flute 22 is formed on the side surface of a drill main body 21 to be rotated about an axial line from the tip to the base end of the drill main body 21 and a cutting edge 25 is formed along the intersecting ridge where the wall surface 23 of the chip discharge flute 22 facing to the drill rotational direction thereof intersects with the tip flank 24 of the main body 21.

Abstract: An endodontic instrument which comprises an elongate shank which has a tapered working length adjacent the pilot end, and at least two continuous helical flutes formed along the tapered working length. The flutes are non-uniformly separated in the axial direction, and they define a relatively broad helical land and at least one relatively narrow helical surface. In one embodiment, the helical surface is a relatively narrow helical land and in another embodiment, the helical surface is a sharp helical edge.

Abstract: Cutting elements or cutter chips (7, 8) are located on a tool body (1). Cutting chip removal spaces (14, 15) are formed in the tool body in three segments. A first segment (I) adjoins the end face (4) of the drill body and includes at least one cutting element seat (10, 11); a chip removal space extends axially, i.e. straight, or slightly obliquely fluted. A second segment (II), adjacent thereto, is formed partially helically with a twist (21) of less than 90.degree. relative to the tool body axis; the second segment (II) terminates axially at a point where, in operation, the direction of radially acting cutting forces coincides essentially with the primary axis of inertia (0-0) of the geometrical moment of inertia. A third segment (III) adjoins the second segment (II); it is essentially straight-fluted.

Abstract: A twist drill comprising a shank section at a top of the drill and a body section at a bottom of the drill, the body section having two or more flutes which spiral downwardly in a first direction and terminate proximate a point, the drill having cutting lips formed by the flutes and operatively arranged to cut material when the drill is rotated in a second direction opposite that of the orientation of the spiral flutes.

Abstract: The invention relates to a twist drill, especially for metals. It has a substantially cylindrical basic component (1) divided into a shaft (2) and a cutting section (3), the central longitudinal axis (5) of which is the axis of rotation of the twist drill. Several swarf grooves (4, 4') are made in the cylindrical surface of the basic component (1) which extend spirally and continuously from the shaft (2) to the drill tip (6) and bound a swarf chamber (35). The feature of the twist drill is that its drill core diameter tapers continuously from the drill tip (6) to the shaft (2).

Abstract: A novel surgical router bit is disclosed which comprises a shaft having a distal end and a proximal end and an outer surface tapering outwardly from its distal end to its proximal end, at least one spiral cutting flute or groove formed in and extending along the length of the shaft from the distal end of the shaft to the proximal end of the shaft, with the at least one spiral cutting flute or groove having a planar floor which is inclined relative to the center axis of the router bit, wherein for each pitch of the at least one spiral cutting flute or groove, the distal end of the floor is level with the tapering outer surface of the shaft and the proximal end of the floor has a fixed depth relative to the tapering outer surface of the shaft so as to define a helical cutting edge of fixed height, and at least one straight cutting flute or groove formed in and extending along the length of the shaft from the distal end of the shaft to the proximal end of the shaft, the at least one straight cutting flute or gro

Abstract: A cutting tool or drill bit (10) has a shank (12) with two ends. A chucking end (14) is on one end of the shank (12) and a cutting end (16) is on the other end of the shank (12). At least one flute (30) is formed on the shank (12) between the chucking (14) and cutting ends (16). The flute (30) includes a web (36) and a debris channel (32). The web (36) includes a first (38) and second (40) surface continuous with a debris channel side wall (34). The first surface (38) is substantially parallel to the shank longitudinal axis (18) and the second surface (40) is on an angle from about 100.degree. to about 120.degree. with respect to the shank longitudinal axis (18). The second surface forms the base of the debris channel or groove (32) with the debris channel side wall (34). The debris channel side wall (34) is on an angle from about 10.degree. to about 20.degree. with respect to the shank longitudinal axis (18).

Abstract: A drill for fiber-filled synthetic plastics has an axially extending body with helical grooves spiraling from a drill point toward a shank end. The grooves define helical lands between them having helical land machining edges. At the point axially tapering land and groove point surfaces converge and land point surfaces with machining edges are radiused to merge gradually with the land surfaces rearward of them. The land machining edges are configured with a negative rake. A plurality of cross notches on the lands extending over an axially extending region of the lands from substantially the axially tapering land point surfaces a predetermined distance toward the shank end are configured to create fiber-snipping crosswise helical cutting edges with a positive rake facing the point.

Abstract: A drill bit is provided with a pair of spiral cutting blades having opposed cutting edges which come together at an angle to form a starting tip. Each of the spiral cutting blades includes a spiral flute which extends longitudinally thereof and is provided with a cutting face thereon. Each cutting edge is provided with an inner edge segment and an outer edge segment wherein the inner edge segment extends outwardly from the starting tip a preselected distance and terminates at an inwardly extending inner wall portion of a gullet. The inner wall portion of the gullet is arcuate in structure and terminates at a preselected inward position with an outer wall of the gullet. The outer wall of the gullet extends angularly outwardly terminating at the intersection with an outer segment of the cutting edge. The outer edge segment of the cutting edge is defined by the outward terminating end of the outer wall of the gullet and the outer most extremity of the cutting edge.

Abstract: A drill but having a drill body with a cutting tip, an axis of symmetry, and a plurality of flutes wherein said flutes have a rake surface at said cutting tip. The cutting tip includes a plurality of side blades between said flutes and joined at a web, a plurality of flank surfaces extending from an outer diameter of said cutting tip to said axis of symmetry, and a plurality of primary cutting edges at the intersection of said flank surfaces with said rake surfaces. Both the rake and flank surfaces have extensions which would intersect each other at an intersection. The primary cutting edges include an angular surface formed on the forward end of said rake surfaces which is located such that the length of said extension of said rake surface measured between said angular surface and said intersection is a first predetermined value and the length of said extension of said flank surface measured between said angular surface and said intersection is a second predetermined value.

Abstract: A drill to cut hardly machinable materials has major flanks extending in a backward direction of rotation from major cutting edges with an ascending slope and ultra-hard cutting grains adhered to said major flanks, at least. When the rotating drill contacts the work-piece, the ultra-hard cutting grains adhered to the most backward part of the major flanks to the direction of rotation cut the work-piece at first. As the ultra-hard cutting grains of the major flanks drop off by the cutting, actual cutting parts move to adjacent part forward of the rotation of the major flanks. Finally, major cutting edges take over the cutting of the work-piece.

Abstract: A drill bit, and associated method of manufacture, characterized by the presence of a low friction coating on the drill flute surfaces and the absence of such coating from the facets on the cutting surfaces of the drill bit. In one form, a tungsten carbide based microdrill bit is coated with a high temperature diamond like carbon to a layer thickness measured in microns. The cutting facets of the microdrill bit are then ground to expose the tungsten carbide material. The microdrill bit formed thereby is particularly useful in creating holes through multilayer printed circuit boards as a part of forming electrical vias. Low friction flute surface coated microdrills exhibit materially longer drill life, better drill location accuracy, can operate at materially greater chiploads, and produce higher quality holes through printed circuit boards.

Abstract: A cutting tool for cutting a honeycomb core having a plurality of spiral blades each of which is formed integratedly with a cylindrical body of the cutting tool and has a lead angle of 60 degrees and more with respect to an axis of the cylindrical body. Each of blades comprises a radial edge with a lip angle ranging from 1 degree to 20 degrees along the periphery of the cutting tool and a bottom edge with a lip angle ranging from 1 degree to 20 degrees at the bottom of the cutting tool. The bottom edge curved outward in the revolutional direction of the blade.

Abstract: A precision twist drill bit provided with two helical teeth separated by grooves. According to the invention, its diameter is equal to the minimum diameter of the hole to be drilled plus 0.005 mm, the width of the land (3) lies in the range 0.1 mm to 0.2 mm, neither tooth is ahead of the other, the end is ground so that it has two slopes with pits (4) that radiate from the center, the cutting edges (1, 2) of the two pits (4) are symmetrical, and all of the surfaces of the drill bit are polished to within an accuracy of less than 0.1 microns Ra.

Abstract: A drill bit for forming holes in a printed circuit board. The drill bit includes a first end including a tip for contacting the material of the circuit board. A second end of the drill bit is attached to apparatus for rotating the drill bit. A cutting edge is in the vicinity of the first end. A pressure pad is opposite the cutting edge. A flute winds upwardly about the drill bit in a helix. An angle of the helix with respect to a longitudinal axis of the drill bit varies continuously, wherein the angle is about from about 15.degree. to about 35.degree. in the vicinity of the first end and increases with increasing distance from the first end to at least from about 35.degree. to about 65.degree..

Abstract: Wear resistant rotary machining tools including twist drill bits, slot drill bits, thread taps, end mills and reamers are disclosed. The tools comprise a body of cemented tantalum, titanium tungsten carbide (1) having a layer of abrasive polycrystalline diamond or cubic boron nitride compact (2) bonded to a convex curved surface of the tool body. The twist drill bits of the invention comprise a layer of abrasive compact of substantially uniform axial thickness extending over substantially the whole top surface of the tip of the drill bit. Methods of manufacturing the wear resistant tools are also disclosed.

Abstract: A drill to cut hardly machinable materials has major flanks extending in a backward direction of rotation from major cutting edges with an ascending slope and ultra-hard cutting grains adhered to said major flanks, at least. When the rotating drill contacts the work-piece, the ultra-hard cutting grains adhered to the most backward part of the major flanks to the direction of rotation cut the work-piece at first. As the ultra-hard cutting grains of the major flanks drop off by the cutting, actual cutting parts move to adjacent part forward of the rotation of the major flanks. Finally, major cutting edges take over the cutting of the work-piece.

Abstract: A drill includes a substantially cylindrical bit body 10 having an axis O. The bit body 10 has a flange portion 13 which includes a converging portion 13a which reduces its diameter progressively towards the front end of the bit body and a flange 13b which is provided with a rearwardly facing annular surface 13c. The annular end surface is contactable with the front end surface of a drill holding portion of a machine too. Chip discharging flutes 14A,14B, each having an inner surface constituted by first and second inner surface portions 14a,14b and a third inner surface portion 14c arcuately recessed therefrom, are formed in the front end portion of the tip body 10. An inner peripheral cutting insert 16A and an outer peripheral cutting insert 16B are mounted on the ends of the chip-discharging flutes 14A,14B. The cross-sectional area S.sub.A of the first-mentioned chip-discharging flute 14A is determined to be greater than that S.sub.B of the second-mentioned chip-discharging flute 14B.

Abstract: A rock drill is formed of an axially extending shank (2) with a drill head (1) at one end and chuck end (3) at the other end. The axially extending outside surface of the shank has at least one helically extending conveying groove (4, 5) and at least one helically extending land (6, 7). The land (6, 7) forms the radially outer surface of the shank (2). Grooves (8, 9) extending perpendicularly of the shank axis are formed in the surface of the land.

Abstract: A boring tool having a tool body (10) which has a pair of chip discharge flutes (11) formed in the peripheral surface thereof. A cutting edge (13) is formed on the edge line where the end relief surface of the tool body intersects the wall surface of each chip discharge flute which faces forwardly as viewed in the direction of the tool rotation. A first margin (15) is provided on the end of the land which is on the trailing side of the flute (11) as viewed in the tool rotation direction, while a second margin (17) is provided on the end of the land adjacent to the heel (16). The lands are provided with recesses (20) in the depths of each of which progressively increase from the first margin towards the second margin. A sub cutting edge (21) is formed on the edge line where the end relief surface meets the wall surface of the recess (20) which faces forwardly as viewed in the direction of the tool rotation.

Abstract: A metal cutting drill includes a shank having cutting edges at a front end and helical flutes extending rearwardly from respective cutting edges for conductive cutting fluid away from the front end. The cross-sectional area of each flute, as seen in a plane oriented non-perpendicular to an axis of rotation of the drill, becomes progressively smaller in a rearward direction. A helix angle defined by each flute becomes progressively smaller in the rearward direction. An angle formed between the plane and another plane oriented perpendicular to the axis equals the helix angle at the location where the planes intersect each other and the axis.

Abstract: This Improved Rotary End Cutting Tool is a completely new concept in twist-drill theory, design, and method of construction. Which will revolutionize the rotary end cutting tool systems as presently known today; especially in larger drill (30) diameters. The new concept of an incurvate cutting-edge (38), purposely orchestrated and offset volumetric grooves (41) combined with a tapered residual core-area (50) in the forward conical forward-end, along with all other renovative improvements. Has virtually resolved drill-chatter, rapid dulling, poor centering, penetration, and even breakage; naming just a few from a list of problems inhabiting currently marketed twist-drills (30). With the overall combined improvements, being to extensive to list herein, having afforded a uniquely simple insert cutting-unit (47) displaying a fixed and removable version capable of equally performing as well as its one-piece counterpart twist-drill (30).

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 bit for cutting hard and abrasive materials has cutting lips formed from sintered polycrystalline diamond (PCD) or polycrystalline cubic boron nitride (PCBN) contained in one or more inserts installed in a drill bit blank. The inserts are made by forming depressions in the upper surface of a matrix slab of tungsten carbide, filling the depressions with fine mesh grains of diamonds or cubic born nitride, subjecting the slab to heat and pressure sufficient to fuse the grains to one another and to the surrounding matrix walls, and then cutting the matrix slab to remove individual inserts containing an elongated vein having an exposed PCD or PCBN surface supported by at least one and preferably two or more side walls of tungsten carbide. A rectangular slot having side walls parallel to one another and equidistant from the diameter of a cylindrical drill bit blank is cut into one transverse end wall of the blank, and one or more inserts placed in the slot.

Abstract: Spiral drill comprising a cylindrical part with two chip grooves (15,16) and a principal maximum stiffness direction (22,23), an attachment part (30) with larger diameter connecting to the cylindrical part at a transition (14), and a tip with indexable cutting inserts (12,13), the chip grooves spirally encircling the cylindrical part to make the principal direction turn an angle C which is at least 110 degrees and at most 125 degrees.

Abstract: The present invention relates to a drill comprising a shaft with chip-conveying flutes and a drill head with two or more cutting elements. Each of the cutting elements comprises a cutting edge which is delimited between a chip-breaking surface and a relief surface and which, at least in the proximity of the geometrical center or rotational axis of the drill, comprises a curved portion. The cutting edge of the individual cutting elements is located with its curved portion in such a way that a tangential point on a straight line that extends from the central axis and tangentially touches said curved edge portion, is provided distantly from the central axis of the drill. In the immediate proximity of this central axis, the cutting edge is terminated in a small material portion which is common for all cutting edges and which extends between the cutting elements in order to serve for centering the drill.

Abstract: A new and improved interchangeable head boring or driving apparatus includes a first head-receiving member which includes a first polygonal-shaped receiving well which is in alignment with a longitudinal axis of the head-receiving member. A plurality of respective interchangeable head assemblies include respective head elements and respective projections which project from the head elements. The respective projections include a first polygonal shape complementary to the first polygonal-shaped receiving well. The respective projections project from the head elements, such that, when the respective projections are inserted into the first polygonal-shaped receiving well, the respective projections and the first polygonal-shaped receiving well arc coaxial along the longitudinal axis. A locking assembly locks the respective projections into the first polygonal-shaped receiving well of the head-receiving member.

Abstract: A modified flute drill which prevents non-circular oval shaped drill holes which occur from incidental lateral or non-axial forces imparted by the operator is provided. The design modification is based on relieving, beveling, or dulling of the leading or side-cutting edge of the flutes of the drill bit for most of the length of the drill bit except for an initial specified length of the flutes where the leading edge of the flutes retains its sharpness and side-cutting capacity. The flute modification additionally imparts to the fluted drill a capacity of self-directional stability after the drill begins its penetration into the material being drilled, at the chosen initial angle of orientation of the drill bit, due to the absence of a side-cutting edge on the following major portion of the drill flutes.

Abstract: A drill bit for drilling holes in concrete and asphalt, or the like, includes a circular drill bit body having two helical grooves in its cylindrical side surface. Pressurized air is injected into the drilled hole through a passage system extending longitudinally within the drill bit. The injected air is forced out of the drilled hole through the helical grooves, such that particulates formed by the drilling process are flushed with the air out of the hole. The flushing action prevents the bit from becoming immobilized by heated asphalt sticking against the drill bit side surface.

Abstract: Drill bit of the twist drill type with turns which are held together by a drill center web and each issue in a radially extending cutting edge of which one extends to the bit axis and the other is shorter than it. This is characterized by the following features:a) the cutting edges (2,3) formed by continuos straight edges lie essentially in a plane coinciding with the bit axis (9),b) the cutting edges (2,3) form an obtuse angle (cutting angle), lying below 180.degree., of at least 175.degree.,c) the cutting edges (2,3;16) having a leading edge angle (K) of about 30.degree. with a rake angle (S.sub.1, S.sub.15) of about 30.degree. to 45.degree.,d) the diameter (D) of the drill center web (6) is at most half the bit diameter.

Abstract: An apparatus machines a workpiece by a rotating cutting tool having at least one coolant channel extended toward the free end thereof with high-pressure coolant jetting onto the free end of the cutting tool. The coolant has sufficient pressure and flow rate to remove the heat and the chips generated during the machining. The cutting tool is fed in a path suitable for each machining operation with the cutting edges being advanced into the workpiece in a reverse direction to the feed direction. The apparatus can machine a workpiece of a material having high hardness and high toughness.

Abstract: A twist drill is disclosed. The twist drill comprises a substantially cylindrical tool body having a rotational axis therethrough, a front portion, a rear portion, a plurality of web thickness, a front flank face, a plurality of flutes formed on an outer peripheral surface thereof and extending to the front flank face, and a land disposed between a pair of the flutes. The flute has a wall portion facing toward the rotational direction of the tool body. A cutting edge is formed at an intersection between the wall portion of the flute and the front flank face. The web thickness at the rear portion of the tool body is smaller than the web thickness at the front portion of the tool body.

Abstract: A router bit for laterally cutting through sheets of wood product, such as plywood and the like. The bit includes a shank portion adapted to be gripped in the chuck of a router, a fluted portion, and a tip. The fluted portion has two helical left-hand flutes. Each flute has a cutting edge and a web portion having a convex surface that extends rearwardly and immediately inwardly from the cutting edge, without a land, in a continuous curve. The flutes are formed by parabolic grinding. In one embodiment the tip is conical in shape and has two diametrically opposed tip flutes for cutting axially into a workpiece. In another embodiment the tip is flat and the bit is adapted only to cut laterally through the workpiece.

Abstract: A drill comprising a solid shank with a first, tip-forming end having cutting edges on opposite second end and a number of flutes corresponding to the number of cutting edges. The flutes extend from the tip end towards the other end and have the purpose of forming and conveying chips from the corresponding cutting edge. At a predetermined distance from the tip, each individual flute turns from a first, chip-forming zone with a predetermined width or cross-sectional area into a second, merely chip-conveying zone with a larger width or cross-sectional area. After having been formed in the first zone, the chips are given the possibility of dilating in the second zone, in order to facilitate chip conveyance.

Abstract: The invention provides a method of manufacturing a twist drill having a cutting insert. The method includes the steps of providing a cutting insert which has a prismatic shape and which comprises a layer of abrasive compact which is bonded to a cemented carbide backing. The insert has on a first facet a cutting edge formed by the abrasive compact layer, and on a second facet a seating surface formed predominantly by the cemented carbide backing. The first and second facets define a predetermined first angle with each other. A twist drill is provided, having a seat in its flank. The seat defines a support surface adapted to receive a seating surface of the insert, and is inclined at a predetermined second angle to the face of the drill. The insert is bonded into the seat, so that the cutting edge of the insert defines the major cutting edge of the drill and the first facet of the insert coincides with the face of the drill. The invention includes cutting inserts and twist drills produced by the method.

Abstract: A drill bit is provided having a novel drill point for drilling a variety of materials. The drill point comprises at least two opposed cutting edges, the cutting edges forming a predetermined drill point angle. The cutting edges have a first radial component between the extreme tip of the drill point and their respective lands. The first radial component is substantially concave. The cutting edges have a second radial component defined generally where the cutting edge merges with its respective land, the second radial component being substantially convex. The drill point of the invention can be applied to any variety of drill bit or cutting tool having any number of flutes, or may comprise a replaceable drill point. A method is also provided for forming the novel drill point according to the invention.

Abstract: A blank material for a drill having a cutting edge and a drill produced from this blank material. The blank material comprises a first blank material having a twisted groove formed on the outer circumference of a columnar base metal sinter and filled with a superhigh pressure sinter, the base metal sinter and the superhigh pressure sinter being sintered and affixed together into one body, and a second blank material composed of a base metal sinter, and the first and the second blank materials are sintered and affixed together at the end faces at superhigh pressure and high temperature. A drill is manufactured by fixing a shank material to the blank material, and forming a twisted cutting edge and a front edge part continuing therefrom, the cutting edge being formed on the superhigh pressure sinter on the first blank material and the front edge part being formed on the second blank material.

Abstract: A rock drill has an axially extending shank (1) with a drill head (2) on one end. The drill head (2) has an end face (3) with a cutting blade (4) and cutting pins (5) extending outwardly from the end face in the drilling direction. The cutting blade (4) extends diametrically across the end face and projects radially outwardly from the drill head (2) and axially outwardly from the end face (3). The cutting pins (5) are arranged on a diameter of the drill head which forms an acute angle relative to the cutting blade (4). Due to the acute angle between the cutting pins and the diametrically arranged cutting blade, removal grooves extending axially from the end face can be enlarged.

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 cutting face substantially parallel to the axis of the drill, the land portion of the two edge portions having a top face joined to the cutting face of the central edge portion and curved in a direction to give a large area to the cutting 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 three-flute, three-tooth drill has a central peak on the central axis between three V-shaped teeth that provides improved cutting chisel edges. The rake faces, which produce the V-shaped cutting teeth, are setback of radial planes of the drill, and have a slight positive rake angle. Gashes are ground into the clearance faces in such a way as to produce the peak with three chisel edges, each of which curves radially out and merges into a straight cutting edge with no reversal in slope. Therefore, the chisel edges cut cleanly, due both to their positive axial rake, and due to the fact that there are no undercuts along their length in which chips could build up.

Abstract: A drilling device for producing drilled holes with an undercut has a drill bit having a drilling head, a depth stop, an enlargement provided between the the drilling head and the depth stop and acting as a swivel bearing, a suction bell rotatably mounted on the depth stop, a bearing washer, and a resilient, ring-shaped cushioning element provided on the depth stop. The cushioning element abuts against the bearing washer and is connected to the suction bell. The depth stop of the drill shank has a concavely curved end face and the bearing washer has a convexly curved sliding face which rests on the concavely curved end face of the depth stop.

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 cutting face substantially parallel to the axis of the drill, the land portion of the two edge portions having a top face joined to the cutting face of the central edge portion and curved in a direction to give a large area to the cutting 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