JP2018164946A - Radius end mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radius end mill which can prevent deposition at a boundary part between a rake face of a peripheral cutting edge and a rake face of a corner blade, which can maintain good cutting discharge property and cutting performance, and which can stably improve a quality of a processed face of a material to be cut.SOLUTION: This radius end mill comprises: a shaft-like end mill body 2; a peripheral cutting edge 8 which is formed on an outer periphery of the end mill body 2; a bottom edge 9 which is formed on a tip of the end mill body 2; a convex-curved corner blade 10 which connects the peripheral cutting edge 8 and the bottom edge 9 to each other, and is convexed toward a tip outer peripheral side of the end mill body 2; a rake face 11 of the peripheral cutting edge 8; a rake face 13 of the corner blade 10 which is formed on a same surface as the rake face 11 of the peripheral cutting edge 8; and plural stripes 17 which are formed from the rake face 11 of the peripheral cutting edge 8 to the rake face 13 of the corner blade 10, so extend as to cross the peripheral cutting edge 8 and the corner blade 10, and are so made as to be parallel to one another.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a radius end mill.

Conventionally, for example, a radius end mill as shown in Patent Document 1 below is known.
This radius end mill has, as cutting edges, a peripheral twisting blade, a bottom blade, and a radius blade (corner blade) that connects the peripheral twisting blade and the bottom blade. Further, these rake surfaces are continuously connected so as to eliminate the step difference between the outer periphery twist rake face of the outer periphery twist blade and the radius rake face of the radius blade.

JP 2006-26839 A

  In the end mill manufacturing process, the radius end mill of Patent Document 1 forms the outer periphery twisted rake face of the outer periphery twisted blade and the radius rake face of the radius blade in different grinding processes (two steps). Therefore, when viewed microscopically, both rake faces are formed with streaks of different orientations given in each grinding step. That is, because the direction of the streak is changed or the streak is divided at the boundary part between the two rake faces, the chip is caught at the boundary part or the frictional resistance is increased, and the welding of the chip is likely to occur. Chip dischargeability and cutting performance were unstable.

  The present invention has been made in view of such circumstances, and can prevent welding at the boundary portion between the rake face of the outer peripheral edge and the rake face of the corner edge, thereby improving chip discharge performance and cutting performance. An object of the present invention is to provide a radius end mill that can be maintained and can stably improve the quality of the work surface of the work material.

  A radius end mill according to an aspect of the present invention includes an end mill body having an axial shape, an outer peripheral blade formed on an outer periphery of the end mill main body, a bottom blade formed on a tip of the end mill main body, the outer peripheral blade and the bottom Convex-curved corner blades that are connected to a blade and project toward the outer peripheral side of the tip end of the end mill body, the rake face of the outer peripheral blade, and the corner formed on the same plane as the rake face of the outer peripheral blade A rake face of the blade, and a plurality of streaks formed from the rake face of the outer peripheral blade to the rake face of the corner blade, extending across the outer peripheral blade and the corner blade, and parallel to each other. It is characterized by.

  In the radius end mill of the present invention, the rake face of the outer peripheral edge and the rake face of the corner edge are formed on the same plane. A plurality of streaks extending in a direction crossing the outer peripheral edge and the corner edge are formed parallel to each other over the rake face of the outer peripheral edge and the rake face of the corner edge. With this special configuration, the following excellent effects can be obtained.

  That is, chips of the work material cut by the outer peripheral edge and the corner edge are easily guided along the lines extending in the direction intersecting the extending direction of the cutting edges (the blade length direction), and easily flow along these lines. It is possible to promote the discharge of chips. Moreover, since the contact area of the chip | tip with respect to a rake face is restrained small by forming the grid, frictional resistance is reduced. Further, by appropriately setting the direction in which the lines extend (the direction in which the lines intersect with the cutting edge), it becomes easy to discharge the chips in the intended direction.

Specifically, unlike the present invention, for example, when trying to control the chip discharge direction by adopting a complicated shape on the surface that is easy to cut, the cutting load on the cutting edge and the rake face is in the blade length direction. Therefore, uneven wear, chipping, etc. are likely to occur. Further, in order to realize a complicated shape, the manufacturing process of the radius end mill becomes complicated.
On the other hand, according to the present invention, even if a complicated shape is not adopted on the face that is easy to cut, the chip is formed by a simple configuration that continuously forms a line from the rake face of the corner blade to the rake face of the outer peripheral edge. Since the discharge direction of the gas can be controlled, the manufacturing process of the radius end mill is not complicated. Moreover, since the cutting load of a corner blade, an outer peripheral blade, and these rake faces can be made uniform along a blade length direction, uneven wear, a chip | tip, etc. can be suppressed.

  Moreover, a coolant (oil-based or water-soluble cutting fluid) can be held in the valleys of the plurality of streaks formed on the rake face. Since these lines intersect (reach) the outer peripheral edge and the corner edge, the coolant is retained in the lines and is less affected by chips flowing on the rake face, while being centrifuged during cutting. The coolant can surely reach the outer peripheral edge and the corner edge by force or the like. Therefore, the coolant can stably improve the cooling effect of the outer peripheral blade, the corner blade and each rake face, and the chip discharge performance.

  According to the present invention, the rake face of the outer peripheral blade and the rake face of the corner blade are formed as the same surface, and the direction of the streak is at the boundary portion between the rake face of the outer peripheral blade and the rake face of the corner blade. No change or streaking. Therefore, it is reliably prevented that chips are caught or the frictional resistance is increased at the boundary portion between these rake faces. In other words, it can be said that the boundary portion is ambiguous and the boundary portion itself does not exist even when viewed microscopically.

  Thereby, chip welding can be prevented on the outer peripheral blade, the corner blade, and each rake face, and the chip discharge performance can be maintained well. Further, the cutting performance (machining accuracy and machining efficiency) can be maintained well, and the quality of the machined surface of the work material can be stably improved.

  In order to continuously form a plurality of parallel lines that are parallel to each other from the rake face of the outer peripheral edge to the rake face of the corner edge, when the radius end mill is manufactured, for example, the rake of the outer peripheral edge is used by using a grinding wheel. It is preferable to continuously grind the face and the rake face of the corner blade in one step. In this case, the manufacturing process of the radius end mill is not increased as compared with the conventional one, while the remarkable effect described above is achieved, and the manufacturing is easy.

  Further, in the radius end mill, the surface roughness along the direction perpendicular to the streaks of the rake face of the outer peripheral edge and the rake face of the corner edge is 0.8 μm or more and 2.0 μm or less at the maximum height roughness Rz. Preferably there is.

  In this case, since the maximum height roughness Rz of the rake face of the outer peripheral edge and the rake face of the corner edge is 0.8 μm or more, the above-described operation and effect due to the formation of the streaks on these rake faces can be reliably obtained. It becomes easy. That is, the effects of facilitating the discharge of chips along the lines, reducing the frictional resistance between the rake face and the chips, and making it easier for the coolant to reach the cutting edge become particularly remarkable.

  Further, since the maximum height roughness Rz is 2.0 μm or less, damage to the crests can be reliably prevented. That is, when the maximum height roughness Rz exceeds 2.0 μm, the ridges of the streak are excessively raised, and the chips are likely to collide, and the ridges may be damaged. In this case, minute separation occurs in the base material (end mill main body), and the function of the mesh becomes unstable. On the other hand, if the maximum height roughness Rz is 2.0 μm or less, the chips flow on the ridge without colliding with the ridge, so that the damage to the ridge is reliably prevented, and the effect of the present invention is achieved. The effect can be achieved stably.

  In the radius end mill, the surface roughness along the direction perpendicular to the streak surface of the rake face of the outer peripheral edge and the rake face of the corner edge is 0.2 μm or more and 1.0 μm or less in terms of arithmetic average roughness Ra. It is preferable.

  In this case, since the arithmetic average roughness Ra of the rake face of the outer peripheral edge and the rake face of the corner edge is 0.2 μm or more, it is easy to surely obtain the above-described operational effect by forming the streaks on these rake faces. Become. That is, the effects of facilitating the discharge of chips along the lines, reducing the frictional resistance between the rake face and the chips, and making it easier for the coolant to reach the cutting edge become particularly remarkable.

  In addition, since the arithmetic average roughness Ra is 1.0 μm or less, it is possible to reliably prevent damage to the crests. That is, when the arithmetic average roughness Ra exceeds 1.0 μm, the crests of the streaks are excessively raised and chips are likely to collide, and the crests may be damaged. In this case, minute separation occurs in the base material (end mill main body), and the function of the mesh becomes unstable. On the other hand, if the arithmetic average roughness Ra is 1.0 μm or less, the chips flow on the peak without colliding with the peak of the streak, so that damage to the peak is reliably prevented, and the effect of the present invention is achieved. Can be played stably.

  Further, in the radius end mill, the streak extends obliquely from the front end along the axial direction toward the rear end side toward the inner side in the radial direction perpendicular to the axis of the end mill body from the outer peripheral blade. It is preferable.

  In this case, the chips generated by cutting with the outer peripheral edge and the corner edge are easily discharged toward the rear end side in the axial direction of the end mill body along the streak. Therefore, the effect that the chip discharging performance is enhanced by the lines becomes more remarkable.

  The radius end mill preferably includes a flank surface of the outer peripheral blade and a flank surface of the corner blade that is smoothly continuous with the flank surface of the outer peripheral blade.

  In this case, the flank face of the outer peripheral edge and the flank face of the corner edge are formed smoothly and continuously with each other (that is, on the same face), and a step, a protrusion, or the like is formed at the boundary between these flank faces. There is nothing to do. Therefore, it is possible to prevent welding, chipping, and the like even at the boundary portion between the flank surfaces.

  Further, in the radius end mill, the center thickness of the end mill main body is the smallest at the front end portion in the axial direction of the end mill main body, and gradually increases from the front end portion toward the rear end side along the axial direction from the front end portion. It is preferable.

In this case, since the center thickness of the end mill body is the smallest at the tip in the axial direction, at the time of manufacturing the radius end mill, for example, the rake face of the outer peripheral edge and the rake face of the corner edge should be integrated using a grinding wheel. It becomes easy to grind continuously in the process. That is, it is possible to secure a large space for inserting the grinding wheel at the tip of the end mill body, and it is easy to form a continuous line between the rake face of the outer peripheral edge and the rake face of the corner edge.
In addition, since the center thickness of the end mill body gradually increases from the front end portion of the end mill body toward the rear end side in the axial direction, sufficient rigidity of the end mill body can be ensured.

  In the radius end mill, it is preferable that the center thickness of the end mill main body is not more than half of the diameter of the blade portion of the end mill main body at least in the axial end portion of the end mill main body.

  In this case, since the core thickness of the end mill body is 50% or less of the blade diameter (the diameter of the blade part) at the tip part of the end mill body, when manufacturing the radius end mill, for example, using a grinding wheel, It is easy to continuously grind the rake face and the rake face of the corner blade in one step. That is, a sufficient space for inserting the grinding wheel can be secured at the tip of the end mill body, and continuous lines are easily formed on the rake face of the outer peripheral edge and the rake face of the corner edge.

  In the radius end mill, the radial rake angle of the bottom blade is a negative angle and the smallest at the connection portion with the corner blade, and the radial rake angle of the corner blade is from the connection portion with the bottom blade to the outer periphery. It is preferable that the diameter gradually increases toward the connection portion with the blade, and is increased at the regular angle and the largest at the connection portion with the outer peripheral blade.

In this case, the radial rake angle of the bottom blade is the negative (negative) angle and the smallest at the connection portion with the corner blade. In other words, the radial rake angle of the bottom blade is maximized on the negative angle side at the connection portion with the corner blade. Thereby, these bottom blades and the corner blades can be smoothly connected without bending the connecting portion between the bottom blades and the corner blades.
Further, the radial rake angle of the corner blade gradually increases toward the positive angle side from the bottom blade to the outer peripheral blade along the edge length direction of the corner blade. Has been the largest. For this reason, the sharpness is sufficiently enhanced in the vicinity of the outer peripheral edge where the cutting amount tends to increase among the corner edges.

  Further, in the radius end mill, a radial angle around a center point of the radius of curvature of the corner blade, and a diameter of the corner blade that is perpendicular to the axis is set to 0 degree at the most advanced position in the axial direction of the end mill body. The rake angle in the normal direction of the corner blade that appears in a cross section that passes through the center point and is perpendicular to the cutting edge of the corner blade, with the position of the outermost end in the direction being 90 degrees, is a range of 0 to 40 degrees in the radiation angle. In the range of 40 degrees to 90 degrees, it is preferable that the diameter gradually decreases from the bottom edge toward the outer edge along the edge length direction of the corner edge.

In this case, the normal rake angle of the corner blade is the largest in the range of 0 to 40 degrees in terms of radiation angle. Therefore, the sharpness in the vicinity of the tip end portion in the axial direction of the corner blade for finishing the processed surface of the work material can be sufficiently increased, and the processing accuracy can be improved.
In addition, when the normal rake angle of the corner blade is in the range of 40 to 90 degrees, the corner blade gradually decreases along the blade length direction of the corner blade from the bottom blade toward the outer peripheral blade. Accordingly, the edge strength can be sufficiently increased in the vicinity of the outer peripheral edge where the cutting amount tends to increase among the corner edges.

  In the radius end mill, the normal rake angle of the corner blade is preferably constant in the range of 0 to 40 degrees as the radiation angle.

In this case, since the normal rake angle of the corner blade is constant in the range of 0 to 40 degrees as the radiation angle, the normal rake angle is maximized on the positive side as described above, and the blade angle is increased. The cutting load can be prevented from acting locally on the cutting edge in the vicinity of the tip in the axial direction of the corner blade that tends to be small. In other words, by making the normal rake angle constant in the blade length direction near the tip of the corner blade in the axial direction where the rake angle is large and it is difficult to ensure the edge strength, the cutting load is evenly distributed in the blade length direction. It is possible to disperse and prevent cutting edge loss.
The above “constant” means that the amount of change in the normal direction rake angle is within 5 degrees within the range of 0 to 40 degrees in the radiation angle.

  Further, in the radius end mill, a round honing is formed at a cutting edge of the corner blade, and a radius of curvature of the round honing that appears in a cross section perpendicular to the cutting edge of the corner blade is in a range of 0 to 40 degrees in the radiation angle. It is preferable to have a maximum value.

  In this case, the radius of curvature of the round honing is the largest in the range of 0 to 40 degrees in the radiation angle where the normal rake angle of the corner blade is the maximum value. In other words, the radius of curvature of the round honing is set to the maximum value in the vicinity of the tip of the corner blade in the axial direction where the rake angle is large and it is difficult to ensure the strength of the cutting edge. it can.

  Further, in the radius end mill, the rake face of the bottom blade is formed in a gash formed at the tip in the axial direction of the end mill body, and the rake face of the bottom blade is a center point of the radius of curvature of the corner blade. It is preferable that it is arranged inside the radial direction perpendicular to the axis.

  In this case, since the rake face of the bottom edge is arranged radially inward from the center point of the radius of curvature of the corner edge, when the radius end mill is manufactured, the rake face of the bottom edge is formed, Both the rake face of the blade and the rake face of the outer peripheral blade are formed on the same surface, which is easy to realize. In other words, it is impossible to form the rake face of the corner blade and the rake face of the outer peripheral edge on the same continuous surface, which would be impossible or hindered by forming the rake face of the bottom blade. The radius end mill can be easily manufactured.

  According to the radius end mill of the present invention, welding at the boundary portion between the rake face of the outer peripheral edge and the rake face of the corner edge can be prevented, and chip dischargeability and cutting performance can be maintained satisfactorily. The quality of the machined surface can be improved stably.

It is a perspective view which shows the radius end mill which concerns on one Embodiment of this invention. It is the front view which looked at the radius end mill of FIG. 1 toward the rear end side from the front-end | tip of the axial direction. It is the side view which looked at the blade part vicinity of the radius end mill of FIG. 1 from radial direction. It is a mimetic diagram showing a plurality of lines formed in a rake face of a peripheral edge, and a rake face of a corner edge. It is a schematic diagram which shows the modification of a streak. It is a schematic diagram which shows the modification of a streak. It is a graph showing the relationship between the cutting edge position of a bottom blade and a corner blade, and a radial rake angle. It is a graph showing the relationship between the radiation angle of a corner blade, a normal direction rake angle, and the curvature radius of a round honing.

  Hereinafter, a radius end mill 1 according to an embodiment of the present invention will be described with reference to the drawings. The radius end mill 1 of the present embodiment is a cutting tool (turning tool) that performs cutting (turning) on a work material made of, for example, a metal material containing titanium.

[Schematic configuration of radius end mill]
As shown in FIGS. 1 to 4, the radius end mill 1 of the present embodiment has a shaft-shaped end mill body 2 made of, for example, cemented carbide or high-speed tool steel.
In the example of the present embodiment, the end mill body 2 has a substantially cylindrical shape. Of the end mill body 2, a blade portion 3 is formed at least at a tip portion along the axis O direction of the end mill body 2, and a portion other than the blade portion 3 is a shank portion 4.

  A cylindrical shank portion 4 in the end mill body 2 is detachably attached to a spindle of a machine tool such as a machining center. The radius end mill 1 is rotated in the tool rotation direction (end mill rotation direction) T around the axis O by the spindle of the machine tool. The radius end mill 1 is supplied with cutting in the direction of the axis O and feeding in the radial direction perpendicular to the axis O along with the above rotation, and cuts the workpiece with the cutting edge of the blade portion 3. The radius end mill 1 performs various cutting processes such as peripheral cutting and face cutting on a work material.

[Definition of direction (direction) used in this embodiment]
In the present embodiment, the direction along the axis O of the end mill body 2 (the direction in which the axis O extends) is referred to as the axis O direction. Further, in the direction of the axis O, the direction from the shank portion 4 to the blade portion 3 is referred to as the front end side, and the direction from the blade portion 3 to the shank portion 4 is referred to as the rear end side.
A direction orthogonal to the axis O is referred to as a radial direction. Of the radial directions, the direction approaching the axis O is referred to as the inner side in the radial direction, and the direction away from the axis O is referred to as the outer side in the radial direction.
A direction that circulates around the axis O is referred to as a circumferential direction. Of the circumferential direction, the direction in which the end mill body 2 is rotated by the main spindle of the machine tool during cutting is referred to as the tool rotation direction T, and the opposite rotation direction to the tool rotation direction T (the counter tool rotation). Direction).

[End mill body]
The core thickness of the blade portion 3 of the end mill body 2 is at most half of the diameter (that is, the blade diameter) of the blade portion 3 at the tip end portion of the end mill body 2 in the axis O direction. Further, the core thickness of the blade portion 3 of the end mill body 2 is the smallest at the tip portion of the end mill body 2 in the axis O direction, and gradually increases from the tip portion toward the rear end side.

  A through-hole 7 is formed in the end mill body 2 so as to penetrate the end mill body 2 in the direction of the axis O. In the example of the present embodiment, the through hole 7 is coaxially arranged on the axis O and opens at the center of the tip surface of the end mill body 2.

  When the work material is cut by the radius end mill 1, coolant is supplied toward the blade portion 3 of the radius end mill 1 and the work surface (work portion) of the work material. For the coolant, an oily or water-soluble cutting fluid or the like is used. The coolant is supplied from the main spindle of the machine tool to the blade portion 3 and the machining surface through the through hole 7 in the end mill body 2. Further, the coolant may be supplied from the outside of the end mill body 2 to the blade portion 3 and the processing surface.

[Chip discharge groove]
A plurality of chip discharge grooves 5 are formed on the outer periphery of the blade portion 3 at intervals in the circumferential direction. The chip discharge groove 5 extends toward the side opposite to the tool rotation direction T along the axis O direction of the end mill body 2 from the front end toward the rear end. These chip discharge grooves 5 may be arranged at irregular intervals in the circumferential direction, or may be arranged at regular intervals.

  The chip discharge groove 5 is open to the front end surface of the end mill body 2. A groove-like gash 6 extending in the radial direction is formed at the tip of the chip discharge groove 5 in the axis O direction. The chip discharge groove 5 is rounded up to the outer periphery of the end mill body 2 at the end portion on the rear end side of the blade portion 3. In other words, in the end mill body 2, a region where the chip discharge groove 5 along the axis O direction is formed is the blade portion 3.

  The chip discharge groove 5 has a wall surface facing the tool rotation direction T, and a portion of the wall surface adjacent to the cutting edge is a rake surface. Specifically, of the rake face of the cutting edge, the portions adjacent to the outer peripheral edge 8, the bottom edge 9 and the corner edge 10 to be described later of the cutting edge are raked on the rake face 11 and the bottom edge 9 of the outer peripheral edge 8, respectively. The face 12 and the rake face 13 of the corner blade 10 are used. The rake face 13 of the bottom blade 9 is formed in the gash 6 in the chip discharge groove 5.

  The end portion on the radially inner side of the gasche 6 is disposed in the vicinity of the axis O. In the example of this embodiment, the inner end in the radial direction of the gash 6 is connected to the through hole 7. The number of the gashes 6 corresponds to the number of the chip discharge grooves 5. In the example of the present embodiment, five gash 6 are formed corresponding to the five chip discharge grooves 5 formed on the outer periphery of the end mill body 2.

[Cutting edge]
A plurality of cutting blades are formed on the blade portion 3 at intervals in the circumferential direction. Each of these cutting edges has an outer peripheral edge 8, a bottom edge 9, and a corner edge 10. Each cutting edge is substantially L-shaped as a whole by connecting the outer peripheral edge 8, the corner edge 10, and the bottom edge 9 to each other. The number of cutting edges corresponds to the number of chip discharge grooves 5, and five (5 sets) cutting edges are provided in the example of this embodiment. That is, the radius end mill 1 of the present embodiment is a five-blade radius end mill.

[Outer peripheral blade]
Out of the cutting edges, the outer peripheral edge 8 is formed on the outer periphery of the blade portion 3 of the end mill body 2. The outer peripheral blade 8 extends toward the side opposite to the tool rotation direction T as it goes from the front end in the axis O direction of the end mill body 2 toward the rear end side.

Specifically, in the blade portion 3, a number (five) of outer peripheral blades 8 corresponding to the number of the chip discharge grooves 5 (five) are arranged at intervals in the circumferential direction. The outer peripheral blade 8 is a lead equal to the chip discharge groove 5 adjacent to the tool rotation direction T, and gradually twists toward the opposite side of the tool rotation direction T from the front end of the end mill body 2 toward the rear end side. It extends in a spiral.
A rotation locus obtained by rotating the outer peripheral blade 8 around the axis O forms one virtual cylindrical surface centered on the axis O.

  The outer peripheral blade 8 is formed on the intersecting ridge line between the wall surface facing the tool rotation direction T in the chip discharge groove 5 and the outer peripheral surface of the end mill body 2. The outer peripheral blade 8 extends in a spiral shape along the outer peripheral edge of the wall surface of the chip discharge groove 5. Specifically, the outer peripheral blade 8 includes the rake face 11 positioned at the radially outer end of the wall surface facing the tool rotation direction T of the chip discharge groove 5 and the chip discharge among the outer peripheral surface of the blade part 3. The groove 5 is formed at an intersecting ridge line with the outer peripheral flank 14 adjacent to the opposite side to the tool rotation direction T of the groove 5.

  On the outer peripheral surface of the blade portion 3, outer peripheral flank surfaces 14 are respectively formed between the chip discharge grooves 5 adjacent in the circumferential direction. In the illustrated example, the width of the outer peripheral flank 14 (the length in the direction perpendicular to the outer peripheral blade 8) is substantially constant along the blade length direction of the outer peripheral blade 8.

In the present embodiment, the outer peripheral blade 8 extends toward the side opposite to the tool rotation direction T along the axis O direction from the front end to the rear end side. (Positive) angle. In the example of this embodiment, the torsion angle of the outer peripheral blade 8 is substantially constant over the entire length of the outer peripheral blade 8. However, the torsion angle of the outer peripheral blade 8 may change so as to gradually increase or decrease from the connecting portion with the corner blade 10 in the blade length direction of the outer peripheral blade 8. Further, the twist angles of the plurality of outer peripheral blades 8 arranged at intervals in the circumferential direction may be different from each other.
The “twist angle” refers to the axis O and the outer peripheral edge 8 (twisted winding) in a side view of the end mill body 2 shown in FIG. 3 (when the end mill body 2 is viewed from the radial direction). Among acute angles and obtuse angles formed between them, it indicates an acute angle.

  In the example of this embodiment, the plurality of outer peripheral blades 8 are arranged at equal pitches in the circumferential direction. The plurality of outer peripheral blades 8 may be arranged at unequal pitches in the circumferential direction.

[Bottom blade]
Among the cutting blades, the bottom blade 9 is formed at the tip of the blade portion 3 of the end mill body 2. The bottom blade 9 extends along the radial direction. A plurality of bottom blades 9 are formed at intervals in the circumferential direction. Specifically, a number (five) of the bottom blades 9 corresponding to the number of the chip discharge grooves 5 (five) are arranged in the blade portion 3 at intervals in the circumferential direction.

  In the side view of the end mill main body 2 shown in FIG. 3, the bottom blade 9 gradually extends slightly toward the rear end side from the outer end in the radial direction toward the inner side in the radial direction. Accordingly, the rotation trajectory obtained by rotating the bottom blade 9 about the axis O is one virtual cone that gradually inclines toward the rear end side from the radially outer end of the bottom blade 9 toward the radially inner side. Forms a surface (tapered surface).

  The bottom blade 9 is formed on the intersecting ridge line between the wall surface facing the tool rotation direction T in the chip discharge groove 5 and the tip surface of the end mill body 2. The bottom blade 9 extends in a curved shape along the leading edge of the wall surface of the chip discharge groove 5. Specifically, the bottom blade 9 includes the rake face 12 positioned at the end portion on the tip side of the wall surface facing the tool rotation direction T in the gash 6 of the chip discharge groove 5 and the tip face of the blade portion 3. It is formed in the intersection ridgeline of the tip flank 15 adjacent to the opposite side to the tool rotation direction T of the gash 6.

  The inner end in the radial direction of the bottom blade 9 is connected to the tip opening edge of the through hole 7. The virtual curve obtained by extending the bottom blade 9 inward in the radial direction does not pass on the axis O, but passes through a position separated from the axis O.

  A tip flank 15 is formed on the tip surface of the blade portion 3 between the chip discharge grooves 5 adjacent in the circumferential direction. In the illustrated example, the width of the tip flank 15 (the length in the direction perpendicular to the bottom blade 9) is substantially constant along the blade length direction of the bottom blade 9.

[Corner blade]
Among the cutting blades, the corner blade 10 is formed on the outer peripheral portion (corner portion) at the tip of the blade portion 3 of the end mill body 2. The corner blade 10 connects the outer peripheral blade 8 and the bottom blade 9, and has a convex curve shape that is convex toward the outer peripheral side of the end of the end mill body 2. In the example of this embodiment, the corner blade 10 is formed in a convex arc shape. The inner edge in the radial direction of the corner blade 10 is gently connected so as to contact the outer edge in the radial direction of the bottom blade 9. The rear end of the corner blade 10 in the axis O direction is gently connected so as to be in contact with the tip of the outer peripheral blade 8 in the axis O direction.

  A plurality of corner blades 10 are formed at intervals in the circumferential direction. Specifically, in the blade portion 3, a number (five) of corner blades 10 corresponding to the number (five) of the chip discharge grooves 5 are arranged at intervals in the circumferential direction.

  The corner blade 10 is formed on a crossed ridge line between a wall surface facing the tool rotation direction T in the chip discharge groove 5 and a front end outer peripheral surface connecting the front end surface and the outer peripheral surface in the end mill body 2. The corner blade 10 extends in a curved shape along the outer periphery of the tip of the wall surface of the chip discharge groove 5. Specifically, the corner blade 10 includes a rake face 13 positioned at a tip outer peripheral portion (corner portion) of the wall surfaces facing the tool rotation direction T in the chip discharge groove 5 and a chip of the tip outer peripheral surface of the blade portion 3. It is formed in the intersection ridgeline of the corner flank 16 adjacent to the opposite side to the tool rotation direction T of the discharge groove 5.

Corner flank surfaces 16 are respectively formed on the outer peripheral surface of the tip of the blade portion 3 between the chip discharge grooves 5 adjacent in the circumferential direction. In the illustrated example, the width of the corner flank 16 (the length in the direction orthogonal to the corner blade 10) is substantially constant along the blade length direction of the corner blade 10.
The flank (corner flank 16) of the corner blade 10 and the flank (outer flank 14) of the outer peripheral blade 8 are smoothly continuous with each other. That is, the corner flank 16 and the outer peripheral flank 14 are formed on the same surface, and no step or protrusion is formed at the connecting portion.

In FIG. 4, at the radial angle around the center point C of the radius of curvature of the corner blade 10, the most extreme position of the end mill body 2 in the direction of the axis O of the corner blade 10 is 0 degree, and the outermost end in the radial direction. The position is defined as 90 degrees. In this case, the normal rake angle (“Rake angle” shown in the graph of FIG. 8) of the corner blade 10 that appears in a cross section passing through the center point C and perpendicular to the cutting edge of the corner blade 10 is the radiation angle (graph of FIG. 8). In the range of 0 to 40 degrees, and in the range of 40 to 90 degrees, from the bottom blade 9 to the outer peripheral blade 8 along the blade length direction of the corner blade 10. It gets smaller gradually as you go.
The normal direction rake angle of the corner blade 10 is constant in the range of 0 to 40 degrees in terms of radiation angle. The above “constant” means that the amount of change in the normal direction rake angle is within 5 degrees within the range of 0 to 40 degrees in the radiation angle.

  Moreover, round honing is formed in the cutting edge of at least the corner blade 10 among cutting edges. The radius of curvature of the round honing that appears in the cross section perpendicular to the cutting edge of the corner blade 10 (“Round honing radius” shown in the graph of FIG. 8) has a maximum value in the range of 0 to 40 degrees in terms of radiation angle.

[Rake face and streak]
In FIG. 4, the rake face 12 of the bottom blade 9 is disposed radially inward from the center point C of the radius of curvature of the corner blade 10. Further, the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 are smoothly continuous with each other. That is, the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 are formed on the same plane, and no step or protrusion is formed at the connecting portion.

  A plurality of streaks 17 are formed from the rake face 11 of the outer peripheral edge 8 to the rake face 13 of the corner edge 10. These lines 17 are parallel to each other and extend across the outer peripheral edge 8 and the corner edge 10. That is, the streak 17 is formed on the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 so as to extend in a direction intersecting with the outer peripheral edge 8 and the corner edge 10.

  In the example of the present embodiment, at the time of manufacturing the radius end mill 1, by using a disc-shaped grinding wheel, the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 are continuously ground in one step. A plurality of streaks 17 are formed. That is, in the example of this embodiment, the streak 17 is a grinding mark.

Further, in the example of the present embodiment, the streak 17 extends obliquely toward the rear end side in the axis O direction as it goes from the outer peripheral blade 8 toward the inside in the radial direction.
Of the acute and obtuse angles formed between the streak 17 and the outer peripheral edge 8, the acute angle θ is, for example, not less than 20 degrees and not more than 60 degrees. More preferably, the angle θ is not less than 30 degrees and not more than 50 degrees. In the example of the present embodiment shown in FIG. 4, the angle θ is about 45 degrees. However, the angle θ is not limited to the above numerical range, and in the modified example of the present embodiment shown in FIG. 5, the angle θ is about 75 degrees. In the modification of the present embodiment shown in FIG. 6, the angle θ is about 15 degrees.

  In the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10, the surface roughness along the direction perpendicular to the streak 17 is 0.8 μm or more and 2.0 μm or less in terms of the maximum height roughness Rz. Moreover, the surface roughness along the direction orthogonal to the streak 17 of the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 is 0.2 μm or more and 1.0 μm or less in terms of arithmetic average roughness Ra.

[Radial rake angle]
FIG. 7 shows the relationship between the cutting edge position along the blade length direction of the end cutting edge 9 and the corner cutting edge 10 and the radial rake angle. It is a graph. In FIG. 7, the radial rake angle of the bottom blade 9 is the negative (negative) angle and the smallest at the connection portion with the corner blade 10. Further, the radial rake angle of the corner blade 10 gradually increases from the connecting portion with the bottom blade 9 toward the connecting portion with the outer peripheral blade 8, and the positive (positive) angle and the largest at the connecting portion with the outer peripheral blade 8. Has been.

[Effects of this embodiment]
In the radius end mill 1 of the present embodiment described above, the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 are formed on the same plane. A plurality of streaks 17 are formed across the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 and extending parallel to each other and intersecting the outer edge 8 and the corner edge 10. With this special configuration, the following excellent effects can be obtained.

  That is, chips of the work material cut by the outer peripheral edge 8 and the corner edge 10 are guided by the lines 17 extending in a direction intersecting the extending direction of the cutting edges (the blade length direction), and the lines 17 It becomes easy to flow along, and can expel the discharge of chips. Further, since the streak 17 is formed, the contact area of the chips with respect to the rake surfaces 11 and 13 is suppressed to be small, so that the frictional resistance is reduced. In addition, by appropriately setting the direction in which the streak 17 extends (the direction in which the streak 17 intersects the cutting edge), chips can be easily discharged in the intended direction.

Specifically, unlike the present embodiment, for example, when trying to control the chip discharge direction by adopting a complicated shape on a surface that is easy to cut, the cutting load on the cutting edge and the rake face is the blade length. Since it fluctuates greatly along the direction, uneven wear or chipping is likely to occur. Further, in order to realize a complicated shape, the manufacturing process of the radius end mill becomes complicated.
On the other hand, according to the present embodiment, the streak 17 is continuously formed from the rake face 13 of the corner edge 10 to the rake face 11 of the outer peripheral edge 8 without adopting a complicated shape on the face that is easy to cut. Since the discharge direction of chips can be controlled with a simple configuration, the manufacturing process of the radius end mill 1 is not complicated. Moreover, since the cutting load of the corner blade 10, the outer peripheral blade 8, and the rake surfaces 13 and 11 can be made uniform along the blade length direction, uneven wear, chipping, and the like can be suppressed.

  In addition, coolant (oil-based or water-soluble cutting fluid) can be held in the valleys of the plurality of lines 17 formed on the rake faces 11 and 13. Since these streaks 17 intersect (reach) the outer peripheral edge 8 and the corner edge 10, the coolant is held in the streak 17 and is not easily affected by the chips flowing on the rake surfaces 11 and 13. However, the coolant can surely reach the outer peripheral edge 8 and the corner edge 10 by centrifugal force or the like during cutting. Therefore, the cooling effect of the outer peripheral blade 8, the corner blade 10, and the rake faces 11 and 13 thereof, and the chip discharging property can be stably enhanced by the coolant.

  According to this embodiment, the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 are formed in the same plane, and the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 are The direction of the streak 17 does not change or the streak 17 is not divided at the boundary between them. Therefore, it is reliably prevented that chips are caught or the frictional resistance is increased at the boundary portion between the rake surfaces 11 and 13. In other words, it can be said that the boundary portion is ambiguous and the boundary portion itself does not exist even when viewed microscopically.

  Thereby, chip | tip welding can be prevented in the outer periphery blade 8, the corner blade 10, and each of these rake faces 11 and 13, and chip | tip discharge property can be maintained favorable. Further, the cutting performance (machining accuracy and machining efficiency) can be maintained well, and the quality of the machined surface of the work material can be stably improved.

  In the present embodiment, when the plurality of lines 17 parallel to each other are continuously formed from the rake face 11 of the outer peripheral edge 8 to the rake face 13 of the corner edge 10, grinding is performed at the time of manufacturing the radius end mill 1. The rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 are continuously ground in one step using a grindstone. Therefore, the manufacturing process of the radius end mill 1 is not increased as compared with the conventional one, while the remarkable effect described above is achieved, and the manufacturing is easy.

  Moreover, in this embodiment, the surface roughness along the direction orthogonal to the stripe 17 of the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 is 0.8 μm or more and 2.0 μm or less in the maximum height roughness Rz. Therefore, the following effects are exhibited.

  That is, in this case, since the maximum height roughness Rz of the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 is 0.8 μm or more, the streak 17 is formed on the rake faces 11 and 13. It becomes easy to obtain the above-mentioned operation effect. That is, the effects of facilitating the discharge of chips along the streak 17, reducing the frictional resistance between the rake surfaces 11, 13 and the chips, and making the coolant easily reach the cutting edge become particularly remarkable.

  Further, since the maximum height roughness Rz is 2.0 μm or less, damage to the crests of the streak 17 can be reliably prevented. In other words, when the maximum height roughness Rz exceeds 2.0 μm, the crests of the streak 17 stand too much and chips easily collide, and the crests may be damaged. In this case, minute peeling occurs in the base material (end mill body 2), and the function of the streak 17 becomes unstable. On the other hand, if the maximum height roughness Rz is 2.0 μm or less, the chips flow on the mountain portion without colliding with the mountain portion of the streak 17, so that the mountain portion is reliably prevented from being damaged. It is possible to stably achieve the operational effects.

  Moreover, in this embodiment, the surface roughness along the direction orthogonal to the line 17 of the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 is 0.2 μm or more and 1.0 μm or less in terms of arithmetic average roughness Ra. Since there is, there exists the following effect.

  That is, in this case, since the arithmetic average roughness Ra of the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 is 0.2 μm or more, the above-described process is achieved by forming the lines 17 on the rake faces 11 and 13. It is easy to reliably obtain the effect of the above. That is, the effects of facilitating the discharge of chips along the streak 17, reducing the frictional resistance between the rake surfaces 11, 13 and the chips, and making the coolant easily reach the cutting edge become particularly remarkable.

  Further, since the arithmetic average roughness Ra is 1.0 μm or less, damage to the crests of the streak 17 can be reliably prevented. In other words, when the arithmetic average roughness Ra exceeds 1.0 μm, the crests of the streak 17 stand too much and chips easily collide, and the crests may be damaged. In this case, minute peeling occurs in the base material (end mill body 2), and the function of the streak 17 becomes unstable. On the other hand, when the arithmetic average roughness Ra is 1.0 μm or less, the chips flow on the mountain portion without colliding with the mountain portion of the streak 17, so that the mountain portion is reliably prevented from being damaged. The effect can be stably achieved.

  Further, in the present embodiment, the streak 17 is inclined and extended toward the rear end side in the axis O direction as it goes radially inward from the outer peripheral blade 8, so that it is cut by the outer peripheral blade 8 and the corner blade 10. The generated chips are likely to be discharged along the line 17 toward the rear end side in the direction of the axis O of the end mill body 2. Therefore, the effect that the chip discharging performance can be enhanced by the streak 17 becomes more remarkable.

In this case, of the acute angle and the obtuse angle formed between the streak 17 and the outer peripheral edge 8, the acute angle θ is preferably 20 degrees or more and 60 degrees or less.
That is, when the angle θ is 20 degrees or more, chips flowing out from the outer peripheral blade 8 inward in the radial direction are less likely to collide with the crests of the streak 17 and are easily guided along the streak 17. The effect obtained can be made particularly remarkable.
Moreover, when the angle θ is 60 degrees or less, the function of guiding chips toward the rear end side of the end mill main body 2 along the streak 17 is stabilized, and chip dischargeability is improved.
In order to further enhance the above-described effects, more preferably, the angle θ is not less than 30 degrees and not more than 50 degrees.

  In the present embodiment, the flank (outer flank 14) of the outer peripheral blade 8 and the flank (corner flank 16) of the corner blade 10 are formed smoothly and continuously with each other (that is, on the same surface). No step or protrusion is formed at the boundary between the flank surfaces 14 and 16. Therefore, it is possible to prevent welding, chipping or the like even at the boundary portion between the flank surfaces 14 and 16.

  Further, in the present embodiment, the center thickness of the end mill body 2 is the smallest at the tip end portion in the axis O direction of the end mill body 2, and gradually increases from the tip portion toward the rear end side in the axis O direction. The following effects are exhibited.

That is, in this case, since the center thickness of the end mill body 2 is the smallest at the tip end in the direction of the axis O, when the radius end mill 1 is manufactured, the rake face 11 and the corner edge 10 of the outer peripheral edge 8 are used with a grinding wheel. It becomes easy to grind the rake face 13 continuously in one step. That is, it is possible to secure a large space for inserting the grinding wheel at the tip of the end mill body 2 (of the chip discharge groove 5), and the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 are continuous. It is easy to form the streak 17 to be formed.
Further, since the center thickness of the end mill body 2 gradually increases from the front end portion of the end mill body 2 toward the rear end side in the axis O direction, sufficient rigidity of the end mill body 2 can be ensured.

  Moreover, in this embodiment, since the core thickness of the end mill main body 2 is less than or equal to half the diameter of the blade portion 3 at least at the tip end portion of the end mill main body 2 in the axis O direction, the following effects are obtained.

  That is, in this case, since the core thickness of the end mill main body 2 is 50% or less of the blade diameter (the diameter of the blade portion 3) at the tip of the end mill main body 2, a grinding wheel is used when the radius end mill 1 is manufactured. It becomes easy to continuously grind the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 in one step. That is, a sufficient space for inserting the grinding wheel can be secured at the tip of the end mill body 2 (of the chip discharge groove 5), and the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 are continuous. It is easy to form the streak 17 to be formed.

Further, in the present embodiment, the radial rake angle of the bottom blade 9 is the negative (negative) angle and the smallest at the connection portion with the corner blade 10. In other words, the radial rake angle of the bottom blade 9 is maximized on the negative angle side at the connection portion with the corner blade 10. Thereby, these bottom blades 9 and the corner blades 10 can be smoothly connected without bending the connecting portion between the bottom blades 9 and the corner blades 10.
Further, the radial rake angle of the corner blade 10 gradually increases to the positive angle side from the bottom blade 9 toward the outer peripheral blade 8 along the blade length direction of the corner blade 10, and is connected to the outer peripheral blade 8. In the part, it is a regular angle and the largest. For this reason, the sharpness is sufficiently enhanced in the vicinity of the outer peripheral edge 8 of the corner edge 10 where the cutting amount tends to increase.

In the present embodiment, the normal direction rake angle of the corner blade 10 is the largest in the range of 0 to 40 degrees in terms of the radiation angle. Therefore, the sharpness in the vicinity of the tip portion of the corner blade 10 in the direction of the axis O, which finishes the processed surface of the work material, can be sufficiently increased, and the processing accuracy can be improved.
Further, when the rake angle in the normal direction of the corner blade 10 is in the range of 40 degrees to 90 degrees, the corner blade 10 gradually decreases from the bottom blade 9 toward the outer peripheral blade 8 along the edge length direction of the corner blade 10. Therefore, the edge strength can be sufficiently increased in the vicinity of the outer peripheral edge 8 where the cutting amount tends to increase in the corner edge 10.

  In the present embodiment, since the normal rake angle of the corner blade 10 is constant in the range of 0 to 40 degrees in terms of the radiation angle, the normal rake angle is maximized on the positive side as described above. Thus, it is possible to prevent the cutting load from acting on the cutting edge locally in the vicinity of the tip end portion in the direction of the axis O of the corner blade 10 which tends to have a small blade angle. In other words, in the vicinity of the tip in the direction of the axis O of the corner blade 10 where the rake angle is increased and it is difficult to ensure the cutting edge strength, the normal rake angle is made constant in the blade length direction, thereby reducing the cutting load in the blade length direction. It is possible to disperse evenly and prevent cutting edge loss.

  Further, in the present embodiment, round honing is formed at the cutting edge of the corner blade 10, and the radius of curvature of the round honing that appears in the cross section perpendicular to the cutting edge of the corner blade 10 is the maximum in the range of 0 to 40 degrees in terms of the radiation angle. Since it has a value, it has the following effects.

  That is, in this case, the radius of curvature of the round honing is maximized in the range of 0 to 40 degrees in the radiation angle where the normal rake angle of the corner blade 10 is the maximum value. That is, since the radius of curvature of the round honing is set to the maximum value in the vicinity of the tip of the corner blade 10 in the direction of the axis O in which the rake angle is increased and it is difficult to ensure the strength of the blade, the cutting edge near the tip of the corner blade 10 Defects can be suppressed.

  Further, in the present embodiment, the rake face 12 of the bottom blade 9 is formed on the gasche 6 formed at the tip portion of the end mill body 2 in the axis O direction, and the rake face 12 of the bottom blade 9 is the corner blade 10. Since it is arranged on the inner side in the radial direction with respect to the center point C of the radius of curvature, the following effects can be obtained.

  That is, in this case, the rake face 12 of the bottom edge 9 is disposed radially inward from the center point C of the radius of curvature of the corner edge 10, so that the rake face of the bottom edge 9 is produced when the radius end mill 1 is manufactured. 12 and the rake face 13 of the corner blade 10 and the rake face 11 of the outer peripheral edge 8 are formed on the same plane. That is, forming the rake face 13 of the corner blade 10 and the rake face 11 of the outer peripheral edge 8 on the same continuous surface becomes impossible or hindered by forming the rake face 12 of the bottom edge 9. The radius end mill 1 is easy to manufacture.

[Other configurations included in the present invention]
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention, for example, as described below.

  In the above-described embodiment, the radius end mill 1 having five blades has been described as an example. However, the number of blades of the radius end mill 1 is not limited to this, and for example, three blades, four blades, and six blades. The above radius end mill 1 may be used.

Further, in the above-described embodiment, the chip discharge groove 5 gradually twists and extends toward the side opposite to the tool rotation direction T as it goes from the front end to the rear end side along the axis O direction on the outer periphery of the end mill body 2. ing. Further, along with this, each outer peripheral blade 8 gradually twists and extends toward the side opposite to the tool rotation direction T as it goes from the front end to the rear end side along the axis O direction on the outer periphery of the end mill body 2. That is, the twist angle of the outer peripheral blade 8 is a positive angle (positive angle). However, the present invention is not limited to this, and the chip discharge groove 5 is gradually twisted in the tool rotation direction T as it goes from the front end to the rear end side along the axis O direction on the outer periphery of the end mill body 2. It may extend. Further, along with this, each outer peripheral blade 8 may be gradually twisted and extended in the tool rotation direction T as it goes from the front end to the rear end side along the axis O direction on the outer periphery of the end mill body 2. That is, the twist angle of the outer peripheral blade 8 may be a negative angle (negative angle).
Further, the outer peripheral blade 8 may include a portion where the twist angle is set to a positive angle and a portion set to a negative angle.

  Further, the maximum height roughness Rz and the arithmetic average roughness Ra of the rake face 11 of the outer peripheral edge 8 and the rake face 13 of the corner edge 10 are not limited to the numerical ranges described in the above embodiments. However, it is preferable that the numerical range described in the above-described embodiment can stably achieve the effects of the present invention.

  Further, in the above-described embodiment, the streak 17 is inclined and extended toward the rear end side in the axis O direction as it goes inward in the radial direction from the outer peripheral blade 8, but is not limited thereto. Absent. That is, the streak 17 may be inclined and extended toward the tip end side in the direction of the axis O as it goes inward in the radial direction from the outer peripheral blade 8. Further, the line 17 may extend from the outer peripheral blade 8 toward the inside in the radial direction.

Moreover, in the above-mentioned embodiment, although the flank 14 of the outer periphery blade 8 and the flank 16 of the corner blade 10 were formed smoothly continuously, it is not limited to this.
Further, chamfer honing may be formed on the cutting edge of the corner blade 10 instead of round honing. Further, the honing may not be formed on the cutting edge of the corner blade 10.

  In addition, in the range which does not deviate from the meaning of this invention, you may combine each structure (component) demonstrated by the above-mentioned embodiment, a modification, and a remark etc., addition of a structure, omission, substitution, others It can be changed. Further, the present invention is not limited by the above-described embodiments, and is limited only by the scope of the claims.

  The radius end mill of the present invention can prevent welding at the boundary portion between the rake face of the outer peripheral edge and the rake face of the corner edge, can maintain good chip discharge and cutting performance, and can process the work material. The surface quality can be improved stably. Therefore, it has industrial applicability.

DESCRIPTION OF SYMBOLS 1 Radius end mill 2 End mill main body 3 Blade part 6 Gash 8 Peripheral blade 9 Bottom blade 10 Corner blade 11 Rake face of outer cutter 12 Rake face of bottom cutter 13 Rake face of corner cutter 14 Outer relief face (flank of outer cutter)
16 Corner flank (flank of the corner blade)
17 Streak C Center point of radius of curvature of corner edge O Axis line

Claims (12)

A shaft-shaped end mill body,
An outer peripheral blade formed on the outer periphery of the end mill body;
A bottom blade formed at the tip of the end mill body;
Connecting the outer peripheral blade and the bottom blade, a convex curved corner blade that protrudes toward the outer periphery of the end of the end mill body; and
A rake face of the outer peripheral edge;
The rake face of the corner blade formed in the same plane as the rake face of the outer peripheral blade,
A radius end mill comprising a plurality of streaks formed from a rake face of the outer peripheral edge to a rake face of the corner edge, extending across the outer peripheral edge and the corner edge and parallel to each other. A radius end mill according to claim 1,
A radius end mill having a maximum height roughness Rz of 0.8 μm or more and 2.0 μm or less in surface roughness along a direction perpendicular to the streaks of the outer peripheral edge and the corner edge. A radius end mill according to claim 1 or 2,
A radius end mill in which a surface roughness along a direction perpendicular to the streaks of the rake face of the outer peripheral edge and the rake face of the corner edge is an arithmetic average roughness Ra of 0.2 μm or more and 1.0 μm or less. It is a radius end mill as described in any one of Claims 1-3,
A radius end mill in which the line extends inclinedly from the front end along the axial direction toward the rear end side from the outer peripheral blade toward the inner side in the radial direction perpendicular to the axis of the end mill body. A radius end mill according to any one of claims 1 to 4,
The flank of the outer peripheral blade,
A radius end mill comprising: a flank face of the corner blade which is smoothly continuous with a flank face of the outer peripheral blade. A radius end mill according to any one of claims 1 to 5,
A radius end mill in which the center thickness of the end mill main body is the smallest at the front end portion in the axial direction of the end mill main body and gradually increases from the front end portion toward the rear end side along the axial direction. It is a radius end mill as described in any one of Claims 1-6,
A radius end mill in which a core thickness of the end mill body is not more than half of a diameter of a blade portion of the end mill body at least in an axial end portion of the end mill body. A radius end mill according to any one of claims 1 to 7,
The radial rake angle of the bottom blade is a negative angle and the smallest at the connection portion with the corner blade,
A radius end mill in which a radial rake angle of the corner blade gradually increases from a connection portion with the bottom blade toward a connection portion with the outer peripheral blade, and is a positive angle and the largest at the connection portion with the outer peripheral blade. A radius end mill according to any one of claims 1 to 8,
The radial angle around the center point of the radius of curvature of the corner blade, and the position of the outermost end in the radial direction perpendicular to the axis is set to 0 degree in the axial direction of the end mill body among the corner blades Is 90 degrees,
The normal rake angle of the corner blade that appears in a cross section that passes through the center point and is perpendicular to the edge of the corner blade has a maximum value in the range of 0 to 40 degrees in the radiation angle, and the 40 to 90 degrees. In a range of degrees, a radius end mill that gradually decreases from the bottom edge toward the outer edge along the edge length direction of the corner edge. A radius end mill according to claim 9,
A radius end mill in which a normal rake angle of the corner blade is constant in a range of 0 to 40 degrees in the radiation angle. A radius end mill according to claim 9 or 10,
A round honing is formed on the edge of the corner blade,
A radius end mill in which the radius of curvature of the round honing which appears in a cross section perpendicular to the cutting edge of the corner blade has a maximum value in a range of 0 to 40 degrees in the radiation angle. It is a radius end mill as described in any one of Claims 1-11,
The rake face of the bottom blade is formed in a gash formed at the tip end in the axial direction of the end mill body,
A radius end mill in which a rake face of the bottom blade is disposed radially inward of a center point of a radius of curvature of the corner blade.

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