Abstract: Flutes or channels are provided at the ramped entryways of an orifice plate of a grinding machine head. Ramped entryways lead from the grinding surface of the orifice plate to one or more hard material collection passages located toward the center of the plate. Providing flutes at the ramped entryway, rather than a smooth surface, helps control the flow of hard material into the hard material collection passages by creating friction to maintain hard materials in the entryway area once collected there, and by encouraging flow of hard materials toward the collection passage.

Abstract: The invention relates to a milling tool intended for chip-removing machining, comprising a basic body rotatable around a geometrical centre axis and a plurality of peripherically spaced-apart, detachable cutting inserts, which separately are securable in insert pockets adjacent to chip channels formed in the basic body, the individual cutting insert having at least one edge formed between a chip surface on the top side of the cutting insert and a clearance surface along the periphery side of the cutting insert, the tool geometry being markedly positive so far that the individual insert pocket is arranged to secure the individual cutting insert in a position in which the chip surface is inclined in relation to the centre axis while forming a positive angle of inclination.

Abstract: A radius endmill has a peripheral cutting edge, a bottom cutting edge, and a rounded corner cutting edges whose ridge line is defined by a circular arc having a given radius as measured in a side view of the endmill that is parallel to the axis. The rounded corner cutting edge is located in a corner portion of the endmill in which the outer peripheral and the axial end intersect each other such that the peripheral cutting edge and the bottom cutting edge are connected to each other through the rounded corner cutting edge. The bottom cutting edge has a radially inner end lying at the axis, and a radially outer end at which the bottom cutting edge is connected to the rounded corner cutting edge. The bottom cutting edge is curved such that its ridge line is defined by a circular arc as seen in a plan view of the endmill that is perpendicular to the axis.

Abstract: A center or non-center cutting end mill for orbital drilling of fiber reinforced plastic (FRP) materials includes a shank, a neck, a cutting head and two or more flutes. The end mill has a tool geometry with the following features: a dish angle between about 2 degrees to about 6 degrees; a helix angle between about 5 degrees to about 18 degrees; an end teeth radial rake angle between about 0 degrees and about 15 degrees; a peripheral teeth radial rake angle between about 8 degrees and about 16 degrees; a gashing axial rake angle between about 3 degrees to about 10 degrees; and a primary clearance angle between about 10 degrees to about 18 degrees. The end mill is made from a tungsten carbide substrate with cemented cobalt in a range between about 3 to 10 wt. % and a diamond coating having a thickness in a range between about 8 to 20 ?m.

Abstract: A method for constructing tambour slats using a system of router bits. The router bit system can include at least two router bits, one of which may have a semi-spherical nose cutting surface and a concave ‘S’ shaped ogee cutting surface; and the other of which may have a ‘S’ shaped ogee cutting surface and a concave quarter round cutting surface. The method for constructing a tambour slat can include milling a groove in a strip of material. The strip of material with a groove may then be milled to form a tongue and a neck portion that may slide into a groove milled in another strip of material. The milling operations may be performed by a router fitted with the router bits from the router bit system. By using the router bit system, each strip of material may yield up to two tambour slats.

Abstract: An indexable milling insert includes opposite top and bottom sides between which a peripheral clearance surface extends, and two opposite cutting edges formed in the transition between the top side and the clearance surface. Each of the cutting edges includes a substantially straight portion connected with a straight section of the clearance surface, and further includes a curved portion connected with a convexly arched section of the clearance surface. A coupling including one or more male- and/or female-like engagement members is located along said clearance surface. Furthermore, the milling insert may be used with a shim plate for attachment to a milling tool.

Abstract: A rotary cutting tool is provided having an axis of rotation, a shank section, a fluted section, and a plurality of helical teeth. The shank section and the fluted section both extend along the axis of rotation. The fluted section has a first end integrally attached to the shank section, a second end, and an outer surface extending between the first and second ends. A plurality of helical teeth is disposed along the outer surface, each having a cutting edge and an undulating geometry. The helical teeth are arranged so that rotationally successive cutting edges are sufficiently dissimilar relative to one another to inhibit a detrimental periodic response in the rotary cutting tool.

Abstract: A toolholder (50) with a controllable critical angle, such as a lead, trailing, rake or clearance angles, includes a tool spindle (42a) for retaining the toolholder in a tool rest (42) of a machine tool. The machine tool (10) includes at least one linear axis, for example, three mutually perpendicular axes, a rotary axis and a rotation axis. The rotary axis and/or rotation axis is controllable to move to a specified position in synchronization with a movement of one of the linear axes. An adaptor (54) supports a cutting tool (56) that is retained in the adaptor by a clamp (58). The cutting tool (56) defines a critical angle, such as a lead angle, a trailing angle, a rake angle and a flank clearance angle, wherein the critical angle is corrected as a vector of movement of at least one of the linear axis is changed. In addition, the cutting tool (56) can be positioned on opposite side of a centerline of rotation of the workpiece to effectively double the life of the cutting tool.

Abstract: An end mill enable to suppress vibrations in cutting and improve chip discharging property, thereby achieving both high cutting efficiency and long tool life. The first clearance angle t1 of outer peripheral edges of the end mill 1 is set to a range of more than 0° to approximately 3°, the first clearance width ?1 of the outer peripheral edges is set to a range of approximately 0.005D or more to approximately 0.03D where the outside diameter is D, and a helix angle ? is set to an equal value for all the outer peripheral edges in a range of approximately 35° or more to approximately 40°. As a result, the vibration in cutting can be suppressed, and the chip discharging property can be improved.

Abstract: A cutting tool having multiple cutting edges includes a tool body having a longitudinal axis, a first cutting edge including a first leading edge that defines a first profile when rotated about the longitudinal axis, and a second cutting edge including a second leading edge that defines a second profile when rotated about the longitudinal axis, the first and second profiles being different from each other and being adapted to cut a workpiece in succession. A method is also disclosed.

Abstract: A cutting tool for cutting a material is provided with a cylindrical body having a cross-sectional diameter and a longitudinal rotating axis, and a plurality of teeth disposed on a circumference of the body, each tooth having a cutting edge and separated by a flute. The number of teeth is selected such that a ratio of the number of teeth to the diameter in millimeter (mm) is at least 0.75:1, that the cylindrical body is rotated with a tooth pass frequency of at least 400 teeth-per-second, and that the tool is used for machining in a way that all the material is removed at a rate of rough machining and in a manner to eliminate finishing pass.

Abstract: In the radius end mill, main gash faces has an angle of inclination with respect to an axis that is smaller than a twist angle of chip discharge flutes. The main gash faces are formed on inner circumferential sides of distal end portions of wall surfaces that face in a tool rotation direction of helically twisted chip discharge flutes, which is formed on an outer circumference of a distal end portion of a tool body that is rotated around the axis. End cutting edges are formed on a distal end of the main gash faces. Sub gash faces has an angle of inclination with respect to the axis that is greater than that of the main gash faces. The sub gash faces are formed on an outer circumferential side of the main gash faces such that they extend away via step portions from the main gash faces.

Abstract: The router bit includes an upper and a lower cutter, axially aligned and separated by a fixed longitudinal displacement. No substantial portion of the bit extends beyond the lower end of the lower cutter. In some embodiments, the lower cutter may be configured with bottom face blades to allow the router to be used as a plunging bit. The cutters may use wing blades or spiral blades. The portion of the bit intervening between the upper and lower cutters may also be configured as a cutter. In some embodiments, the router bit is integral. In other embodiments, it comprises separate elements that may be axially secured.

Abstract: A rotary multi-tooth milling cutter, each tooth having a tooth face is provided. The tooth face has at least two sections, a first section nearest the cutting edge having a convex form as viewed in a cross section perpendicular to the cutter axis and a second section in a concave form.

Abstract: The present invention relates to tools for the machining of materials by milling or drilling. The invention provides an improved form for an end mill having a semi-spherical cutting end, or flat cutting end, or drill end the center area of which is configured to better eject chips and thus to improve the surface finish of the metal work piece and tool life. The comprising a body portion to be gripped by a machine tool and a plurality of flutes machined to form a cutting tooth adjacent to the flute, each tooth being provided with a chisel edge, the cutting end being semispherical, or flat, or like drill point and when viewed endwise there being seen a cutting edge starting proximate to the tool center at a position B above the x axis and 0.5A to the right of the y axis.

Abstract: A thread mill that is to be moved along a helical interpolation path while being rotated about an axis of the thread mill in a rotating direction, for forming a thread in a circumferential surface of a workpiece. The thread mill includes a cylindrical main body having (a) at least one spiral flute formed in an outer circumferential surface of the cylindrical main body, and (b) at least one cutting edge each provided by a rear-side one of widthwise opposite edges, as viewed in the rotating direction, of a corresponding one of the at least one spiral flute. Each of the at least one spiral flute extends in a direction opposite to the rotating direction as viewed in a direction away from a proximal end of the cylindrical main body toward a distal end of the cylindrical main body. Also disclosed is a method of forming the thread by using the thread mill.

Abstract: A cutting portion for rotary cutting machining includes a cutting edge structure which comprises at least one cutting edge which is integral with the cutting portion. The cutting portion includes a fastening structure for mounting of the cutting portion to the holder. The cutting portion includes a gripping structure for a wrench that shall be used for mounting the cutting portion to the holder. The cutting portion includes an intermediate, substantially round, part provided between the first fastening structure and the cutting edge structure. The intermediate part includes at least one friction surface provided with one or more recesses or one or more protrusions intended to cooperate with a wrench. The recess or protrusion has a component extending substantially radially.

Abstract: A milling tool 1, in particular a tubular drill, includes a shaft 2 and a working portion 3. At least one cutting edge 8 is provided at a face of the working portion 3 and at least one bore 4 extends into the face of the working portion 3. The axis of the bore 4 extends axially parallel or in an angle, preferably between 0° and 20°, with respect to an axis 5 of the tool 1.

Abstract: A rotary cutting tool comprises a shank extending along an axis of rotation of the cutting tool and a fluted portion adjacent the shank, the fluted portion having an effective flute length and a plurality of peripheral cutting edges indexed about the axis of rotation. At least one of the plurality of peripheral cutting edges is formed such that a two-dimensional representation of the peripheral cutting edge in schematic development view follows a quadratic curve over the effective flute length.

Abstract: An end mill 10 is a tool for milling a metal block such as a metal mold and is placed in a machine tool such as a milling machine when in use. The end mill 10 is used to provide a rotary milling cutter and a milling method using the same, in which it is possible to perform orthogonal milling and pocket milling to efficiently form four corners with small radius, without repeatedly milling using a small-diameter end mill. The end mill 10 has two cutting edges 11a and 11b at its distal portion, and an edge angle D1 formed by the two cutting edges 11a and 11b is 70.53 degrees.

Abstract: A multi-function miller cutter includes a shank with a receiving portion defined in the shank at an end of the shank. A threaded hole is defined in the receiving portion so as to secure a disposable cutter. An angle is defined between an axis of the shank and a center of the threaded hole.

Abstract: In a ball end mill, cutting can be carried out with high precision, and abrasion or breakage of the cutting blade can be reduced. The ball end mill is provided with a cutting blade section having a cutting blade, which is U-shaped in front view, at the end section of a shank. The cutting blade is provided on a flat surface deviated by a predetermined distance from the shank axis, and comprises blade faces having rake faces, which become negative angles at the time of cutting. In cross-section intersecting the cutting blade, all the blade faces have the same shape.

Abstract: The invention relates to a rotary cutting tool (1) extending along a longitudinal axis (10) and comprising a first cutting portion (4) including a plurality of first helical teeth (12) having a given helix direction and being designed to work in a first direction of rotation of the tool. According to the invention, said tool also includes a second cutting portion (8) including a plurality of second helical teeth (16) having, as helix direction, the given helix direction and being designed to work in a second direction of rotation of the tool, opposed to the first. The preferred application is in the field of aeronautical constructions.

Abstract: In this insert, in addition to the insert being formed so that the cutting edge is twisted at a helix angle within the range of 5° to 25° about the axis when the insert is attached to the insert mounting seat, the thickness of the insert body at the flank located on a straight line, which passes through the center of the rough hemisphere formed by the rotational locus of the cutting edge and forms an angle of inclination of 90° relative to the axis, is set to be within the range of 0.5 D to 0.9 D relative to the thickness D of the rough plate that composes the insert body. As a result, since a comparatively gentle but adequately large helix angle is imparted to the cutting edge, cutting resistance decreases. In addition, since the thickness of the insert body at the flank on the rear end side of the insert body is not excessively thin, the rigidity of the insert body is adequately secured.

Abstract: A rotary cutting end mill is provided. The end mill includes a shank section and a fluted section. The fluted section has a first end integrally attached to the shank section, a second end, and an outer surface. One or more helical teeth are disposed along the outer surface of the fluted section. Each helical tooth has a cutting surface and a relief wall that intersect to form an angle defining a helical cutting edge. The helical cutting edge defines an outer circumferential cutting path. The cutting surface includes first, second, and third sections, and first and second take-off peaks. The first take-off peak is disposed between the first section and second section. The second take-off peak is disposed between the second section and the third section.

Abstract: A rotary multi-tooth milling cutter, each tooth having a tooth face is provided. The tooth face has at least two sections, a first section nearest the cutting edge having a convex form as viewed in a cross section perpendicular to the cutter axis and a second section in a concave form.

Abstract: Face milling cutter with a shaft section and a tool section, whereby the front end of the tool section has at least one flat, arched, lower cutting edge, a rounded corner cutting edge, and a peripheral cutting edge, whereby the lower cutting edge has a radius r1 from 1 to 2 times d1 and begins at a distance of 0.1 to 0.2 d1 to the axis of the shaft section, whereby d1 is the diameter of the flight circle of the axially parallel tangent to the rounded corner cutting edge.

Abstract: A shank milling cutter includes a cutting portion which is intended to come into engagement with the workpiece, wherein the envelope surface of the cutting portion is substantially cylindrical. At least one major cutting edge is arranged at the peripheral surface of the cutting portion and at least one minor cutting edge (face cutting edge) is arranged at the end face of the cutting portion and with an end diameter D. The minor cutting edge, in projection onto a plane containing the milling cutter axis, has a convexly curved portion with a radius of curvature R>D/2 and a center of curvature M located such that a distance from the center of curvature M to the axis is in a range from zero to a value smaller than D/2.

Abstract: A technique having superior efficiency for manufacturing a bevel gear forging die is presented. In the present invention, raw material is machined by means of a radius end mill, manufacturing a bevel gear forging die 10. In recent years, it has become possible to use radius end mills to form complex shapes from raw materials having a high degree of hardness, owing to the fact that NC construction devices and their controlling programs control the deployment of radius end mills, and due to the improved accuracy of the radius end mill itself. By improving the process path of the radius end mill, the inventors have succeeded in creating a process whereby a radius end mill can be used to cut a bevel gear forging die 10 having a side face, a base face, and a diagonal face.

Abstract: Tools, including end mills, include a flute having a helix which varies along the length of the tool. The invention is not limited in terms of the number of flutes, whether odd or even; helix change(s) within a flute or between flutes; or indexing between cutting edges or flutes. Nor is the invention limited in terms of materials used, and may employ carbide or high-speed steel grades of materials, ceramics, or any other material that will be used in the future for material removal in a rotary tool. According to the invention, a ‘slow’ or ‘high’ helix may be used at the end or starting point of the tool, depending upon the application. A slow helix at the end or starting point is desirable for a strong corner in ramping and plunging into the material. When a higher helix is used at the end transitioning to a smaller helix at the shank, the corner is also protected because of the helix change. The high helix at the tip may be needed for shearing action in a given material.

Abstract: A cutting tool having a blade section on one end is mounted on a spindle of a cutting machine, and the blade section is contacted with a workpiece to perform planing of the workpiece into a desired shape. Because the tip of the blade section is disposed on the spindle axis, the position of the cutting edge is controlled by performing drive control of the X-axis and Y-axis of the spindle. Thus, the control of the cutting machine is simplified, and path errors resulting from synchronous control can be eliminated.

Abstract: A shank-end tool is described that is simple and economical to manufacture, with permanently attached wing-like inserts for the milling-type machining of chipless materials that remains functional with unavoidable frictional wear and with increasing erosion. The shank-end tool is characterized by a shank (1) rotatable around its longitudinal axis (2) that can be connected detachably to a drive device and is provided at its free end section (6) with at least one groove-shaped recess (7) extending in the axial direction and one flat cutter blade (8), which is provided with a non-cutting blade edge (12) on its leading face viewed in the direction of advance (9). The shank-end tool is used for the manufacture of molds, especially heat-resistant casting molds for the production of metal castings.

Abstract: A milling cutter includes a body having three cutting edges formed by the body. An end of the body situated opposite the cutting edges defines a fastening end of the milling cutter. Each cutting edge extends from an outer periphery of the body substantially to a center rotational axis of the body along a substantially convexly curved path. Radially outer and radially inner ends of each cutting edge are situated axially rearwardly of an axially foremost point of the cutting edge. Each cutting edge lies on a respective imaginary sphere having a radius which has a center which that is spaced from the cutting edge in a direction toward the fastening end and spaced radially from the center axis.

Abstract: A cemented carbide ball end mill comprises a cutting portion with a semi-spherical ball portion at a tip thereof. The cutting edge portion has a cutting edge rake face and a chip evacuating flute at the ball portion. An angle formed by a straight line connecting a vertex of the ball portion, where an intersection line passes through, and another end of the intersection line with respect to the central axis, is from 30° to 50°. Further, and angle formed by the rake face and the chip evacuating flute is from 100° to 150°, and a width of the chip evacuating flute is 0.5 to 5 times as large as a radius of the ball portion.

Abstract: A milling tool has a cutting edge geometry with a main cutting edge, a cutting corner, optionally with a bordering planar cutting edge segment, and a secondary cutting edge. The tool is used for milling to achieve the smoothest level surface possible parallel to the rotational axis of the milling tool. Each main cutting edge is formed to result in a generatrix of the envelope curve described by the rotation of the milling tool that has a first outwardly curving segment and a second inwardly curving segment. The first segment increases in its distance from the rotational axis from the beginning of the segment to the end of the segment. The distance of the second segment decreases from its beginning towards its end. The tangents at each point of the second segment encompass an angle ?2 of more than 0° and up to 3° with a parallel to the rotational axis.

Abstract: A throwaway-type cutting tool including a tool body having a distal end, and a plurality of throwaway tips mounted to the distal end. Each of the plurality of throwaway tips including a plate of a substantially rectangular shape. The plate has a corner angle of two adjacent corner cutting edges of a first side in a surface being to 90° or less, and two opposing ridges on the first side including the two adjacent corner cutting edges are defined as cutting edges which are in a non-parallel orientation to each other. Each of the plurality of throwaway tips have a cutting edge arranged to project toward the distal end. The two adjacent corner cutting edges on the first side in each of the plurality of throwaway tips are arranged to project toward an outer periphery of the distal end of the tool body.

Abstract: An apparatus for making microlens molds and microlens array molds is described which utilizes a forming element having a rotating half radius diamond cutting member. A substrate is alignably arranged with the diamond cutting member so that the cutting member can mill a mold cavity in the substrate. The apparatus can be used to make high sag lens molds with high accuracy and a nearly 100% fill factor.

Abstract: A rotary end-mill is disclosed having a deferential flute construction with all individual flutes being unequally spaced about the circumference of the cylindrical tool body at different helix angles.

Abstract: The invention refers to a tool (1), a machine tool, and a method for cutting machining of a workpiece. The tool includes a mounting portion (5) for mounting of the tool in the machine tool, a tool shaft (7), which has a first inner end (7?), connected to the mounting portion (5), a longitudinal center axis (a), which extends through the mounting portion and the tool shaft, and a main cutting edge (9) on the tool shaft. The main cutting edge (9) has an extension in an axial direction along an imaginary envelope surface, which is concentric to the center axis (a) and located radially outside an outer periphery surface of the tool shaft (7). The main cutting edge (9) is arranged to permit cutting engagement with said workpiece when the tool is rotated around the longitudinal center axis.

Abstract: In a radius end mill having a bottom edge formed on the end face thereof, a radius edge designed in a substantially quarter arc shape and formed at a corner portion thereof, and an outer peripheral edge formed spirally on the side surface thereof, the bottom edge and the radius edge being continuously connected to each other at a connecting point A while the radius edge is continuously connected to each other at a connecting point B, when a view taken along a plane that passes through the connecting points A and B and crosses a rake face of the radius edge is represented by an R cross-sectional view, the rake face of the radius edge is designed to have a convex curved line extending from the connecting point A to the connecting point B in the R cross-sectional view.

Abstract: An apparatus for making microlens molds and microlens array molds is described which utilizes a forming element having a rotating half radius diamond cutting member. A substrate is alignably arranged with the diamond cutting member so that the cutting member can mill a mold cavity in the substrate. The apparatus can be used to make high sag lens molds with high accuracy and a nearly 100% fill factor.

Abstract: A cutting tool for cutting a material is provided with a cylindrical body having a cross-sectional diameter and a longitudinal rotating axis, and a plurality of teeth disposed on a circumference of the body, each tooth having a cutting edge and separated by a flute. The number of teeth is selected such that a ratio of the number of teeth to the diameter in millimeter (mm) is at least 0.75:1, that the cylindrical body is rotated with a tooth pass frequency of at least 400 teeth-per-second, and that the tool is used for machining in a way that all the material is removed at a rate of rough machining and in a manner to eliminate finishing pass.

Abstract: A rotary end-mill is disclosed having a deferential flute construction with all individual flutes being unequally spaced about the circumference of the cylindrical tool body at different helix angles.

Abstract: A cutter bit is provided which includes a body having a pair of free ends with a cutter bit mounted adjacent each free end. A boss extends outwardly from the center of the body such that a portion of the body and the cutter bit may be mounted in a rotary cutting tool to allow the second cutter bit to be utilized. The bit is reversible such that either cutter bit may be positioned within the chuck of a rotary cutter tool while the cutter bit mounted on the opposite side of the body is utilized. A method of mounting a cutter bit in a rotary cutter tool is also provided which includes steps of loosening the bit within the chuck of the rotating cutting tool, removing the bit from the chuck, rotating the bit end to end, replacing the end of the bit that was out of the chuck originally into the chuck, and tightening the chuck.

Abstract: The ball nose end mill cutter according to the present invention includes a cutting face 12 providing a plurality of alternating crest 52 and root 54 profiles arranged with respect to each other to further provide a serrated cutting edge 16 on the cutter. The serrations and serrated cutting edge positioned on a cutter insert 10 for removable affixation to a tool body 20 having a centerline of rotation 28, and including an insert body 18 having a contact surface 30 for mating engagement with a mounting surface of the tool body. The ball nose end mill insert further including a curved cutting face surface 12, and a plurality of face serrations formed along the curved cutting face surface, the face serrations having face crests 116 and face roots 216 forming a serrated curved cutting edge 16.

Abstract: The invention is a rotary cutter having both coarse teeth and fine teeth. The coarse tooth gives great cutting and removal of the dust fast, then the fine tooth can finish the surface smoothly. The invention improves cutting speed and has smooth surface finish. The invention can apply to different head shapes, such as ball, cylinder, cone etc.

Abstract: A power tool chuck and bit shank system for attaching changeable tool bits to a power tool such as a router. The chuck includes a body having a bore which is sized to accept a tool bit shank. At least two movable gripping jaws are included for gripping the tool bit shank, which are moved with a tightening mechanism. At least one flat surface is provided in at least a section of the bore for mating with at least one corresponding flat surface provided on a tool bit shank to prevent rotational movement of the tool bit shank within the bore. A tool bit shank having a flat surface can be gripped in the chuck with hand tightening of the tightening mechanism, and a tool bit shank without a flat surface can be gripped in the chuck with assisted tightening of the tightening mechanism.

Abstract: A milling cutter comprising at least one cutting end and a cutter shank. The at least one cutting end including a core of cutter material having a cutter axis. The core includes a plurality of cutting edges extending therefrom, wherein the total cross-sectional area of the cutter material, taken at right angles to the cutter axis, increases gradually from the cutting end towards the cutter shank.

Abstract: A cutter bit is provided which includes a body having a pair of free ends with a cutter bit mounted adjacent each free end. A boss extends outwardly from the center of the body such that a portion of the body and the cutter bit may be mounted in a rotary cutting tool to allow the second cutter bit to be utilized. The bit is reversible such that either cutter bit may be positioned within the chuck of a rotary cutter tool while the cutter bit mounted on the opposite side of the body is utilized. A method of mounting a cutter bit in a rotary cutter tool is also provided which includes steps of loosening the bit within the chuck of the rotating cutting tool, removing the bit from the chuck, rotating the bit end to end, replacing the end of the bit that was out of the chuck originally into the chuck, and tightening the chuck.

Abstract: In a ball end mill, cutting can be carried out with high precision, and abrasion or breakage of the cutting blade can be reduced. The ball end mill is provided with a cutting blade section having a cutting blade, which is U-shaped in front view, at the end section of a shank. The cutting blade is provided on a flat surface deviated by a predetermined distance from the shank axis, and comprises blade faces having rake faces, which become negative angles at the time of cutting. In cross-section intersecting the cutting blade, all the blade faces have the same shape.