JP2018075658A - Roughing end mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roughing end mill capable of improving processing efficiency by enhancing sharpness, and capable of also lengthening the tool service life by preventing an edge defect.SOLUTION: In a roughing end mill having an end mill body 1 of forming a shaft shape and an outer peripheral blade 5 for extending toward the base end side from the tip in the axis O direction of the end mill body 1 and formed in a wave shape of recessing-projecting in the radial direction orthogonal to the axis O when viewed from the end mill rotation direction T around the axis O of the end mill body 1, the outer peripheral blade 5 comprises a projection part 13 of projecting to the outside in the radial direction and a recessed part 14 of recessing to the inside in the radial direction, and in a cross-sectional view vertical to the axis O, a rake face of the projection part 13 comprises a first rake face 21 adjacent to the inside in the radial direction of the projection part 13 and being a negative angle in a rake angle θ1 and a second rake face 22 of continuing with the inside in the radial direction of the first rake face 21 and being a positive angle in a rake angle θ2.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a roughing end mill.

  Conventionally, for example, a luffing end mill as shown in Patent Documents 1 to 3 below is known. The luffing end mill includes an end mill main body having an axial shape, and an outer peripheral blade extending from the end of the end mill main body in the axial direction toward the base end. The outer peripheral blade is formed in a wave shape that is uneven in the radial direction perpendicular to the axis as viewed from the end mill rotation direction around the axis of the end mill body.

  At the time of cutting, the roughing end mill has a feed rate per tooth that is smaller than the amplitude of the irregularities (concave and convex portions) of the outer peripheral blade (the difference in height between the top end of the convex portion and the bottom end of the concave portion, nick depth). The feed is given in the radial direction, and the workpiece is cut by the convex portion of the outer peripheral blade while generating divided chips.

JP 2010-173056 A JP 2010-179424 A JP 2011-161555 A

However, the conventional luffing end mill has the following problems.
That is, there is room for improvement in that the cutting edge of the outer peripheral blade can be prevented and the tool life can be extended while improving the cutting efficiency of the outer peripheral blade and improving the machining efficiency.

  Specifically, by increasing the rake angle of the outer peripheral edge to the positive angle side, the sharpness is improved and the machining efficiency is improved, but in this case, the cutting edge strength is reduced and chipping (cutting edge defect) is likely to occur. Become. Further, by increasing the rake angle of the outer peripheral blade to the negative (negative) angle side, the strength of the blade edge is increased and chipping is suppressed, but in this case, the sharpness is lowered and the machining efficiency is affected.

  The present invention has been made in view of such circumstances, and provides a luffing end mill that can improve cutting efficiency by improving the cutting efficiency, and can prevent tool tip breakage and extend tool life. It is an object.

  One aspect of the present invention includes an end mill body having an axial shape, the end line extending from the distal end in the axial direction of the end mill body toward the proximal end, and the axial line as viewed from the end mill rotation direction around the axial line of the end mill body. A roughing end mill having a corrugated outer peripheral blade that is undulated in a radial direction orthogonal to the outer peripheral blade, wherein the outer peripheral blade protrudes outward in the radial direction and recessed inward in the radial direction. A rake face of the convex portion adjacent to the inside of the radial direction of the convex portion and having a negative rake angle, as viewed in a cross section perpendicular to the axis. And a second rake face that is continuous with the inside of the first rake face in the radial direction and has a positive rake angle.

The luffing end mill generates chips that are cut into short pieces by cutting the protrusions into the work material among the protrusions and recesses of the outer peripheral edge during cutting.
According to the present invention, the rake face in the convex portion of the outer peripheral edge includes a first rake face whose rake angle is a negative angle, and a second rake face whose rake angle is a positive angle. It is equipped with. That is, the convex part of the outer peripheral blade has a rake face with a two-step rake angle.
The “rake angle” as used in the present invention is defined as follows. In a cross-sectional view (transverse cross-sectional view) perpendicular to the axis of the end mill body, the rake angle (first rake angle) of the first rake face is a first imaginary straight line that passes through the convex portion (the top end) of the outer peripheral blade and the axis. Is the acute angle of the acute angle and the obtuse angle formed by intersecting the first virtual straight line and the first rake face. Further, in this cross-sectional view, the rake angle (second rake angle) of the second rake face is determined by taking the second imaginary straight line passing through the recess (bottom end) of the outer peripheral edge and the axis as a reference plane. Among acute angles and obtuse angles formed by intersecting the virtual straight line and the second rake face, it indicates an acute angle.

  Therefore, at the time of cutting, a component cutting edge formed by compressing chips is formed on the first rake face. The component cutting edge has a substantially triangular shape in the cross-sectional view, and has a flank surface located on an extension line of the flank surface of the outer peripheral blade and a rake face located on an extension line of the second rake face. ing. Since the rake face of the component cutting edge (the surface facing the end mill rotation direction in the component blade edge) is formed so as to be smoothly continuous with the second rake face, the rake angle of the component edge is the rake angle of the second rake face. Similarly, it becomes a positive angle. The sharpness of the convex portion of the outer peripheral blade is enhanced by this configuration cutting edge.

Moreover, the component cutting edge which was formed on the 1st rake face and contributed to cutting is discharged | emitted accompanying other chips. That is, the constituent cutting edge is repeatedly generated and discharged on the first rake face. At this time, since the constituent cutting edges are discharged each time including cutting heat, the temperature rise of the outer peripheral blade is effectively suppressed.
In addition, the outer peripheral blade has a wave shape having a convex portion and a concave portion, and the constituent cutting edges generated on each convex portion are easily discharged along with the chips generated by the respective convex portions. . That is, since the generation and discharge of the constituent cutting edges are stably performed on the respective convex portions of the outer peripheral blade, the above-described operational effects become remarkable.

And although the sharpness of a convex part is heightened with a constituent blade edge | tip, since the rake angle of the actual blade edge | tip of this convex part is formed in the negative (negative) angle | corner, blade edge intensity | strength is fully ensured. Therefore, even when the roughing end mill is used for high-feed roughing or the like, chipping of the outer peripheral blade is prevented.
As described above, according to the present invention, the cutting efficiency of the outer peripheral blade can be improved to improve the machining efficiency, and the tool life can be extended by preventing the chipping of the blade edge.

  In the luffing end mill, it is preferable that the first rake face has a linear shape in a cross-sectional view perpendicular to the axis.

  In this case, since the first rake face is formed in a flat shape, it is easy to stably form the constituent cutting edges on the first rake face without a gap.

  In the luffing end mill, the rake angle of the first rake face is preferably −45 ° or more in a cross-sectional view perpendicular to the axis.

  In this case, since the rake angle of the first rake face is −45 ° or more, the rake angle of the first rake face is suppressed from becoming too large on the negative angle side, and is stably on the first rake face. The constituent cutting edge can be formed, and the constituent cutting edge can be attached to the chip and easily discharged. The above-mentioned “rake angle is −45 ° or more” means that the angle value of the rake angle is −45 ° or larger than the −45 ° on the positive angle side.

  In the luffing end mill, it is preferable that the first rake face has a concave curve shape in a cross-sectional view perpendicular to the axis.

  In this case, since the first rake face is formed in a concave curved surface shape, the constituent cutting edge formed on the first rake face can be easily discharged stably. Specifically, since the rake angle of the end portion adjacent to the cutting edge of the first rake face is larger than the rake angle of the portion other than the end portion, the rake angle is increased from the end portion accordingly. Chips are easily generated and the generated cutting edges are easily pushed out from the first rake face by the generated chips.

  Further, in the luffing end mill, a cross section perpendicular to the axis line, where a maximum diameter of the outer peripheral blade is a blade diameter D and a distance from a top end of the convex portion to a bottom end of the concave portion along the radial direction is a nick depth H In view, the curvature of the first rake face is preferably (0.2 × blade diameter D) or more and (1 / nick depth H) or less.

  In this case, since the curvature of the first rake face is (0.2 × blade diameter D) or more in a cross-sectional view perpendicular to the axis of the end mill body, the first rake face is formed in a straight line. It can suppress and form in a concave curve shape reliably, and can improve the discharge | emission property of a constituent blade edge stably. Moreover, since the curvature of a 1st rake face is (1 / nick depth H) or less, while suppressing that a 1st rake face curves too much, among the 1st rake faces, the edge part which adjoins a blade edge | tip. It is possible to prevent the rake angle from being set to a positive angle and to reliably form the constituent cutting edge on the first rake face.

  Further, in the luffing end mill, the outer peripheral blade is along a virtual string winding extending toward the opposite side to the end mill rotation direction from the distal end of the end mill body toward the proximal end side, and the first rake face It is preferable that a boundary line with the second rake face extends in parallel with the virtual string winding.

  In this case, when the end mill is manufactured, the first rake face and the second rake face are not formed along the unevenness of the outer peripheral edge, but the first rake face and the second rake face are formed along the virtual chord winding of the outer peripheral edge. Since it can be formed, it is easy to manufacture.

  In the luffing end mill, the first rake face is formed in a region from the top end of the convex part to the bottom end of the concave part along the radial direction, and the rake face of the bottom end of the concave part is the second rake face. It is preferable that the rake face is formed.

  In this case, the first rake face on which the component cutting edge is formed is formed in a region from the top end of the convex portion to the bottom end of the concave portion. That is, the first rake face is formed according to the nick depth of the outer peripheral blade. The rake face at the bottom end of the recess is formed by a second rake face having a positive rake angle. Therefore, at the time of cutting, even if the feed amount per blade is set larger than the nick depth, the sharpness at the bottom end of the recess is sufficiently ensured.

  According to the luffing end mill of the present invention, the cutting efficiency can be improved to improve the machining efficiency, and the tool life can be extended by preventing the chipping of the cutting edge.

It is a perspective view which shows the roughing end mill which concerns on one Embodiment of this invention. It is a figure which expands and shows the blade part of FIG. It is a side view of a luffing end mill. It is a figure which expands and shows the blade part of FIG. It is a front view of a luffing end mill. It is a cross-sectional view (cross-sectional view perpendicular to the axis) of the luffing end mill. It is a figure which expands and shows the outer periphery blade vicinity of the luffing end mill of FIG. It is a cross-sectional view of a modification of the luffing end mill. It is a figure which expands and shows the outer periphery blade vicinity of the roughing end mill of FIG.

  Hereinafter, a roughing end mill 10 according to an embodiment of the present invention will be described with reference to the drawings. The luffing end mill 10 of the present embodiment is a cutting tool used for cutting such as roughing or intermediate finishing.

[Schematic configuration of luffing end mill and end mill body]
As shown in FIGS. 1 to 5, the luffing end mill 10 of the present embodiment has an axial shape, and has an end mill body 1 made of, for example, a cemented carbide or high-speed tool steel.
The end mill main body 1 has a substantially columnar shape, and a blade portion 2 is formed at least at a tip portion along the axis O direction of the end mill main body 1, and a portion other than the blade portion 2 is a shank portion 3.

  In the luffing end mill 10, a cylindrical shank portion 3 in the end mill body 1 is attached to a main shaft of a machine tool such as a machining center, and the main shaft is rotated in an end mill rotation direction T around an axis O. The luffing end mill 10 is provided with cutting in the direction of the axis O along with the rotation and feeding in the radial direction perpendicular to the axis O, and cuts into the work material made of a metal material or the like. Rolling). The luffing end mill 10 performs various types of processing such as side processing, grooving, deep engraving, and pocket processing on the work material.

  When the work material is cut by the luffing end mill 10, coolant is supplied toward the blade portion 2 of the luffing end mill 10 and the work surface (work portion) of the work material. As the coolant, for example, an oily or water-soluble cutting fluid or compressed air is used. The coolant is supplied from the main spindle of the machine tool to the blade portion 2 and the machining surface through the inside of the end mill body 1, or is supplied to the blade portion 2 and the machining surface from the outside of the end mill body 1.

[Definition of direction (direction) used in this embodiment]
In the present embodiment, the direction along the axis O of the end mill body 1 (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 3 to the blade portion 2 is referred to as the distal end side, and the direction from the blade portion 2 to the shank portion 3 is referred to as the proximal 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 directions, the direction in which the end mill main body 1 is rotated at the time of cutting is referred to as an end mill rotation direction T, and the opposite rotation direction is referred to as the side opposite to the end mill rotation direction T (anti-end mill rotation direction).

[Chip discharge groove]
A plurality of chip discharge grooves 4 are formed on the outer periphery of the blade portion 2 at intervals in the circumferential direction. These chip discharge grooves 4 are arranged at equal intervals or unequal intervals in the circumferential direction. In the example of the present embodiment, four chip discharge grooves 4 are formed on the outer periphery of the blade portion 2.

  The chip discharge groove 4 extends in the circumferential direction from the distal end in the axis O direction of the end mill body 1 toward the proximal end side. In the present embodiment, the chip discharge groove 4 opens at the distal end surface of the end mill main body 1 and gradually twists toward the side opposite to the end mill rotation direction T as the distance from the distal end surface toward the proximal end increases. It extends in a shape. The chip discharge groove 4 is rounded up to the outer periphery of the end mill main body 1 at the end portion on the proximal end side of the blade portion 2. In other words, in the end mill body 1, a region where the chip discharge groove 4 along the axis O direction is formed is the blade portion 2.

  Each chip discharge groove 4 has a wall surface facing the end mill 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, portions adjacent to the outer peripheral edge 5 and the bottom edge 9 described later of the cutting edge are set as the rake face 11 of the outer peripheral edge 5 and the rake face 12 of the bottom edge 9, respectively. ing. The rake face 11 of the outer peripheral blade 5 will be described in detail later.

  A groove-like gash 7 extending along the radial direction is formed at the tip of the chip discharge groove 4. The end portion on the radially inner side of the gasche 7 is disposed in the vicinity of the axis O, and the depth in the direction of the axis O is gradually increased from the radially inner end toward the radially outer side.

  The number of the gashes 7 corresponds to the number of the chip discharge grooves 4, and in the example of the present embodiment, four gashes 7 are formed. As shown in FIG. 5, among these gash 7, a pair of gash 7 adjacent in the circumferential direction, that is, a set of the gash 7, communicate with each other at the radially inner end of each gash 7. In addition, the blade lengths of the two bottom blades 9 (short blades) cut out by the set of the gashs 7 among the four bottom blades 9 are the same as the blade lengths of the two bottom blades 9 (long blades) not cut out. Than it is shorter.

[Cutting edge]
As shown in FIGS. 1 to 5, the blade portion 2 has a plurality of cutting blades spaced apart from each other in the circumferential direction. Each of these cutting edges has an outer peripheral edge 5 and a bottom edge 9. By connecting the outer peripheral blade 5 and the bottom blade 9 to each other, one (one set) of cutting blades having a substantially L shape as a whole is formed. The number of cutting edges corresponds to the number of chip discharge grooves 4, and four (four sets) cutting edges are provided in the example of this embodiment. That is, the roughing end mill 10 of this embodiment is a four-blade roughing end mill.

[Bottom blade]
A bottom blade (tip blade) 9 is formed on the intersecting ridge line between the wall surface facing the end mill rotation direction T in the chip discharge groove 4 and the tip surface of the end mill body 1. The bottom blade 9 extends substantially linearly along the tip edge of the wall surface of the chip discharge groove 4. In the example of the present embodiment, when the end mill main body 1 shown in FIG. 5 is viewed from the front (when the front end surface of the end mill main body 1 is viewed from the axis O direction to the front), the end portion on the radially outer side of the bottom blade 9 is A concave curve is formed, and portions other than the end are linear.

1 to 5, the bottom blade 9 includes a rake face 12 positioned at an end portion on the tip end side and a tip end face of the blade portion 2 among the wall surfaces facing the end mill rotation direction T of the chip discharge groove 4 (gash 7). Of these, the chip discharge groove 4 is formed at the intersecting ridge line of the tip flank 8 adjacent to the side opposite to the end mill rotation direction T.
A tip flank 8 is formed on the tip surface of the blade portion 2 between the chip discharge grooves 4 adjacent in the circumferential direction. In the example of the present embodiment, the width of the tip flank 8 (the length in the direction orthogonal to the bottom blade 9) is substantially constant except for the portions corresponding to both ends of the bottom blade 9 in the radial direction. . The tip flank 8 is inclined toward the base end side in the direction of the axis O as it goes from the bottom blade 9 to the side opposite to the end mill rotation direction T, whereby a clearance angle is given to the bottom blade 9. .

  In the end mill front view shown in FIG. 5, a plurality (four in the example of the present embodiment) of the bottom blades 9 are spaced from each other in the circumferential direction and extend along the radial direction. The bottom blades 9 have a plurality of (a pair in the example of this embodiment) long blades not cut by the gash 7 and a plurality (a pair in the example of this embodiment) cut out by the gash 7. And a short blade. Of the bottom blade 9, the end edge on the radially inner side of the long blade is disposed close to the axis O. In addition, a gap corresponding to the width of the gash 7 is formed between the end edge of the short blade in the radial direction of the bottom blade 9 and the axis O.

In the side view of the end mill body 1 shown in FIGS. 3 and 4, the bottom blade 9 is slightly inclined toward the base end side in the axis O direction from the radially outer edge toward the radially inner edge. It extends. For this reason, the rotation locus formed by the bottom blade 9 rotating around the axis O has a conical surface (tapered surface) shape.
The bottom blade 9 may extend so as to be included on a virtual plane perpendicular to the axis O. In this case, the rotation locus of the bottom blade 9 is a plane perpendicular to the axis O.

  In the example of the present embodiment, the radially outer end of the bottom blade 9 is connected to the tip of the outer peripheral blade 5 in the axis O direction. However, the present invention is not limited to this, and a convex arc-shaped corner R blade that protrudes toward the outer peripheral side of the tip end of the end mill body 1 may be formed at a connection portion between the bottom blade 9 and the outer peripheral blade 5. .

[Outer peripheral blade]
1 to 5, an outer peripheral blade 5 is formed on the intersecting ridge line between the wall surface facing the end mill rotation direction T in the chip discharge groove 4 and the outer peripheral surface of the end mill main body 1. The outer peripheral blade 5 extends from the tip end in the axis O direction of the end mill body 1 toward the base end side, and is formed in a wave shape that is uneven in the radial direction when viewed from the end mill rotation direction T.

  Further, the outer peripheral blade 5 extends along a virtual chord winding (not shown) extending toward the side opposite to the end mill rotation direction T as it goes from the distal end of the end mill main body toward the proximal end side. This imaginary string winding is a reference line extending in parallel with the direction in which the chip discharge groove 4 extends. That is, the outer peripheral blade 5 is a lead equal to the chip discharge groove 4 adjacent to the end mill rotation direction T, and gradually twists toward the side opposite to the end mill rotation direction T from the distal end of the end mill body 1 toward the proximal end side. It extends.

The outer peripheral blade 5 includes a rake face 11 positioned at the radially outer end of the wall surface facing the end mill rotation direction T of the chip discharge groove 4 and an end mill of the chip discharge groove 4 out of the outer peripheral surface of the blade part 2. It is formed at the intersection ridge line with the outer peripheral flank 6 adjacent to the opposite side to the rotation direction T.
On the outer peripheral surface of the blade portion 2, outer peripheral flank surfaces 6 are formed between the chip discharge grooves 4 adjacent in the circumferential direction. The outer peripheral flank 6 has a wave shape that is uneven in the radial direction corresponding to the uneven shape of the outer peripheral blade 5. Specifically, the outer peripheral flank 6 is formed in a wavefront shape in which concave curved surfaces and convex curved surfaces are alternately arranged along the virtual string winding (the extending direction of the outer peripheral blade 5 and the blade length direction of the outer peripheral blade 5). ing. In the example of the present embodiment, the width of the outer peripheral flank 6 (length along the circumferential direction) is substantially constant along the extending direction of the outer peripheral blade 5. The outer peripheral flank 6 is inclined inward in the radial direction from the outer peripheral blade 5 toward the side opposite to the end mill rotation direction T, whereby a clearance angle is given to the outer peripheral blade 5.

  A plurality (four in the example of the present embodiment) of the outer peripheral blades 5 extend substantially in parallel with each other at intervals in the circumferential direction. As shown in FIG. 2 and FIG. 4, the outer peripheral blade 5 has a convex portion 13 protruding outward in the radial direction and a concave portion 14 recessed inward in the radial direction. In the example of the present embodiment, when the outer peripheral blade 5 is viewed from the end mill rotation direction T, the convex portion 13 has a convex curve shape protruding outward in the radial direction, and the concave portion 14 is directed inward in the radial direction. It has a concave concave shape.

  The outer peripheral blade 5 has a plurality of convex portions 13 and concave portions 14, respectively, and these convex portions 13 and concave portions 14 are alternately arranged along the virtual string winding. Thereby, the outer peripheral blade 5 has a sinusoidal shape. In the example of the present embodiment, a straight portion 15 extending substantially parallel to the virtual chord winding is provided at the distal end portion of the outer peripheral blade 5 in the axis O direction, and the convex portion 13 is provided at a portion other than the distal end portion. And the recessed part 14 has comprised the waveform which continues smoothly.

  The corrugations of the irregularities formed by the convex portions 13 and the concave portions 14 in each outer peripheral blade 5 have the same shape, and the positions (phases) in the axis O direction are shifted from each other. For this reason, one virtual cylindrical surface centering on the axis O is formed on the outermost periphery of the rotation locus obtained by rotating the plurality of outer peripheral blades 5 around the axis O.

[Rake face of outer peripheral edge]
As shown in FIGS. 2, 4, 6, and 7, the rake face 11 of the outer peripheral blade 5 is the first rake face 21 whose rake angle is a negative (negative) angle, and the rake angle is positive (positive). ) A second rake face 22 which is a corner. That is, the rake face 11 of the outer peripheral edge 5 is a rake face having a two-step rake angle.

  In a cross-sectional view perpendicular to the axis O of the end mill body 1 shown in FIG. 7, the rake face of the convex portion 13 of the outer peripheral blade 5 is adjacent to the inner side in the radial direction of the convex portion 13, and the rake angle θ <b> 1 is a negative angle. The first rake face 21 and a second rake face 22 that is continuous with the inside of the first rake face 21 in the radial direction and has a rake angle θ2 of a positive angle. The rake face of the outer peripheral blade 5 other than the bottom end located at the inner edge in the radial direction of the recess 14 includes a first rake face 21 and a second rake face 22. The rake face at the bottom end of the rim is provided with a second rake face 22 adjacent to the inside of the recess 14 in the radial direction.

The “rake angle” in the present embodiment is defined as follows.
In a cross-sectional view (transverse cross-sectional view) perpendicular to the axis O of the end mill body 1 shown in FIG. 7, the rake angle (first rake angle) θ1 of the first rake face 21 is the top end of the convex portion 13 of the outer peripheral blade 5 (the top end thereof). ) And the first imaginary straight line L1 passing through the axis O, the acute angle and the obtuse angle formed by intersecting the first imaginary straight line L1 and the first rake face 21 are indicated as an acute angle. . Further, in this cross-sectional view, the rake angle (second rake angle) θ2 of the second rake face 22 is defined by taking the second imaginary straight line L2 passing through the recess 14 (bottom end) of the outer peripheral blade 5 and the axis O as a reference plane. As an acute angle and an obtuse angle formed by intersecting the second imaginary straight line L2 and the second rake face 22, an acute angle is indicated.
In FIG. 7, the first rake angle θ1 is a negative angle, and the second rake angle θ2 is a positive angle.

Specifically, in the example of the present embodiment, the first rake face 21 of the rake face 11 of the outer peripheral blade 5 extends from the top end (radially outer edge) of the convex part 13 along the radial direction to the bottom of the concave part 14. The rake face of the bottom end of the concave portion 14 is formed by the second rake face 22.
2 and 4, the boundary line BL between the first rake face 21 and the second rake face 22 extends in parallel with the virtual chord winding. In the example of this embodiment, the boundary line BL extends in parallel to the virtual string winding through the bottom end of the recess 14. In the rake face 11 of the outer peripheral edge 5, the boundary line BL forms a ridge line shape that is convex toward the end mill rotation direction T.

In the present embodiment, in a cross-sectional view perpendicular to the axis O shown in FIG. 7, the first rake face 21 has a linear shape, and the second rake face 22 has a concave curve shape. Further, in this cross-sectional view, the rake angle θ1 of the first rake face 21 is −45 ° or more. “The rake angle θ1 is −45 ° or more” indicates that the angle value of the rake angle θ1 is −45 ° or larger on the positive angle side than −45 °. Specifically, since the rake angle θ1 is a negative angle as described above, the rake angle θ1 is −45 ° or more and less than 0 °. Moreover, the maximum length (maximum rake width) along the radial direction of the first rake face 21 is, for example, not less than 0.0025 mm and not more than 0.5 mm. The maximum rake width is obtained by the following formula, for example.
Maximum rake width = (0.25 to 0.7) x feed amount per blade Feed amount per blade = 0.01 to 0.5 mm / tooth

  Further, the length (rake width) along the radial direction of the first rake face 21 is the largest at the top end of the convex portion 13 and gradually decreases as it is separated from the top end along the blade length direction of the outer peripheral blade 5. It becomes zero at the bottom end of the recess 14.

  8 and 9 show a modification of the present embodiment. In this modification, the first rake face 21 has a concave curve shape in a cross-sectional view perpendicular to the axis O of the end mill body 1 shown in FIG. Specifically, the maximum diameter of the outer peripheral blade 5 (the maximum diameter of the rotation trajectory obtained by rotating the outer peripheral blade 5 around the axis O) is the blade diameter D, and the concave portion 14 extends from the top end of the convex portion 13 along the radial direction. When the distance to the bottom end is the nick depth H, the curvature of the first rake face 21 is (0.2 × blade diameter D) or more in a cross-sectional view perpendicular to the axis O shown in FIG. / Nick depth H) or less.

[Effects of this embodiment]
The roughing end mill 10 of the present embodiment described above generates shortly divided chips by cutting the convex portion 13 into the work material among the convex portion 13 and the concave portion 14 of the outer peripheral blade 5 at the time of cutting.
According to the present embodiment, the rake face in the convex portion 13 of the outer peripheral blade 5 is the first rake face 21 in which the rake angle θ1 is a negative (negative) angle, and the rake angle θ2 is a positive (positive) angle. And a second rake face 22. That is, the convex portion 13 of the outer peripheral blade 5 has a rake face with a two-step rake angle.

  Accordingly, as shown in FIGS. 7 and 9, a component cutting edge BE formed by compressing chips is formed on the first rake face 21 at the time of cutting. This component cutting edge BE has a substantially triangular shape in a cross-sectional view perpendicular to the axis O, and extends the flank (outer flank 6) of the outer flank 5 (the outer flank 6 extends in the end mill rotation direction T). And a rake face located on an extension line of the second rake face 22 (an extension line extending the second rake face 22 radially outward). The rake face of the component cutting edge BE (the surface facing the end mill rotation direction T in the component cutting edge BE) is formed so as to be smoothly continuous with the second rake face 22, and therefore the rake angle of the component cutting edge BE is the second rake angle. The positive angle is the same as the rake angle θ2 of the surface 22. The sharpness of the convex portion 13 of the outer peripheral blade 5 is enhanced by the constituent cutting edge BE.

In addition, the component cutting edge BE formed on the first rake face 21 and contributing to cutting is discharged along with other chips. That is, the constituent cutting edge BE is repeatedly generated and discharged on the first rake face 21. At this time, since the component cutting edge BE is discharged each time including cutting heat, the temperature rise of the outer peripheral blade 5 is effectively suppressed.
The outer peripheral blade 5 has a wave shape having a convex portion 13 and a concave portion 14, and the component cutting edge BE generated on each convex portion 13 is attached to the chips generated by each convex portion 13. It is easy to be discharged. That is, since the generation and discharge of the component cutting edge BE are stably performed on each convex portion 13 of the outer peripheral blade 5, the above-described effects are remarkable.

And although the sharpness of the convex part 13 is heightened by the component cutting edge BE, the actual cutting edge of the convex part 13 has a rake angle θ1 formed in a negative (negative) angle, so that the cutting edge strength is sufficiently ensured. . Therefore, even when the luffing end mill 10 is used for high-feed roughing or the like, chipping of the outer peripheral blade 5 is prevented.
As described above, according to the present embodiment, it is possible to improve the cutting efficiency of the outer peripheral blade 5 and improve the machining efficiency, and to prevent the cutting edge from being lost and extend the tool life.

In the present embodiment, since the first rake face 21 is linear in a cross-sectional view perpendicular to the axis O shown in FIG.
That is, in this case, since the first rake face 21 is formed in a flat shape, it is easy to stably form the constituent cutting edge BE on the first rake face 21 without a gap.

  In the present embodiment, the rake angle θ1 of the first rake face 21 is −45 ° or more in a cross-sectional view perpendicular to the axis O shown in FIG. As a result, the rake angle θ1 of the first rake face 21 can be prevented from becoming too large on the negative angle side, and the constituent cutting edge BE can be stably formed on the first rake face 21, and the constituent cutting edge can be formed. The BE can be attached to the chips and easily discharged.

Moreover, in the modification of this embodiment, since the 1st scoop surface 21 has comprised the concave curve shape by the cross sectional view perpendicular | vertical to the axis line O shown by FIG. 9, there exists the following effect.
That is, in this case, since the first rake face 21 is formed in a concave curved surface shape, the constituent cutting edge BE formed on the first rake face 21 can be easily discharged stably. Specifically, the rake angle θ1 of the end portion adjacent to the cutting edge (the upper end portion of the first rake face 21 in FIG. 9) of the first rake face 21 is larger than the rake angle θ1 of a portion other than the end part. Since it becomes larger on the regular angle side, new chips are easily generated from the end portions, and the component cutting edge BE is easily pushed out from the first rake face 21 by the generated chips.

Further, in the modification of the present embodiment, the curvature of the first rake face 21 is (0.2 × blade diameter D) or more (1 / nick depth H) in a cross-sectional view perpendicular to the axis O shown in FIG. ) Because of the following, the following effects are achieved.
That is, in this case, since the curvature of the first rake face 21 is (0.2 × blade diameter D) or more in a cross-sectional view perpendicular to the axis O of the end mill body 1, the first rake face 21 is formed in a straight line. Therefore, it is possible to reliably form a concave curve, and to stably improve the discharge performance of the constituent cutting edge BE. Moreover, since the curvature of the 1st rake face 21 is (1 / nick depth H) or less, while suppressing that the 1st rake face 21 curves too much, among the 1st rake faces 21, it adjoins a blade edge | tip. The rake angle θ1 of the end portion (the upper end portion of the first rake face 21 in FIG. 9) is prevented from being set to a positive angle, and the constituent cutting edge BE can be reliably formed on the first rake face 21. .

Further, in the present embodiment, the outer peripheral blade 5 has a virtual chord winding (reference line parallel to the chip discharge groove 4) extending toward the side opposite to the end mill rotation direction T as it goes from the distal end of the end mill body 1 toward the proximal end. The boundary line BL between the first rake face 21 and the second rake face 22 extends in parallel with the virtual chord winding, so that the following effects are obtained.
That is, in this case, at the time of manufacturing the end mill, the first rake face 21 and the second rake face 22 are not formed along the unevenness of the outer peripheral edge 5, but the first rake face 21 along the virtual chord winding of the outer peripheral edge 5. And since the 2nd rake face 22 can be formed, manufacture is easy.

Moreover, in this embodiment, the 1st rake face 21 is formed in the area | region from the top end of the convex part 13 along a radial direction to the bottom end of the recessed part 14, and the rake face of the bottom end of the recessed part 14 is the 2nd rake face 22 Therefore, the following effects are obtained.
That is, in this case, the first rake face 21 on which the component cutting edge BE is formed is formed in a region from the top end of the convex portion 13 to the bottom end of the concave portion 14, that is, the first rake face 21 is nick depth of the outer peripheral blade 5. It is formed according to the height H. The rake face at the bottom end of the recess 14 is formed by a second rake face 22 having a rake angle θ2 of a positive angle. Therefore, even when the feed amount per blade is set to be larger than the nick depth H during cutting, the sharpness at the bottom end of the recess 14 is sufficiently ensured.

[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, in the above-described embodiment, four chip discharge grooves 4 are formed on the outer periphery of the blade part 2, and four (4 sets) of cutting edges are formed on the blade part 2. The number of 4 and the cutting edge is not limited to four each, and may be three or less or five or more.

  Further, in the above-described embodiment, when the outer peripheral blade 5 is viewed from the end mill rotation direction T, the convex portion 13 has a convex curvilinear shape that protrudes outward in the radial direction, and the concave portion 14 is concave inward in the radial direction. Although it is assumed to have a curved shape, it is not limited to this. For example, the convex portion 13 may have a composite convex R shape that combines a convex curve and a straight line, and the concave portion 14 may have a composite concave R shape that combines a concave curve and a straight line.

  In the above-described embodiment, the boundary line BL between the first rake face 21 and the second rake face 22 passes through the bottom end of the recess 14 and extends in parallel to the reference line (virtual chord winding) of the outer peripheral blade 5. However, it is not limited to this. That is, the boundary line BL may be disposed radially inward from the bottom end of the recess 14, or may be disposed radially outward from the bottom end of the recess 14.

  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 luffing end mill of the present invention can improve the cutting efficiency by improving the sharpness, and can prevent the cutting edge from being lost and extend the tool life. Therefore, it has industrial applicability.

DESCRIPTION OF SYMBOLS 1 End mill main body 5 Peripheral blade 10 Roughing end mill 13 Convex part 14 Concave part 21 First rake face 22 Second rake face BE Constitution blade edge BL Boundary line D Blade diameter H Nick depth O Axis line T End mill rotation direction θ1 First rake face Corner (first rake angle)
θ2 Rake angle of the second rake face (second rake angle)

Claims (7)

A shaft-shaped end mill body,
An outer peripheral blade that extends from the distal end in the axial direction of the end mill body toward the proximal end side and is undulated in a radial direction perpendicular to the axis as viewed from the end mill rotation direction around the axis of the end mill body Roughing end mill equipped with,
The outer peripheral blade is
A convex portion protruding outward in the radial direction;
A concave portion recessed inward in the radial direction,
In a cross-sectional view perpendicular to the axis,
The rake face of the convex part is
A first rake face adjacent to the inside of the convex portion in the radial direction and having a negative rake angle;
A roughing end mill, comprising: a second rake face continuous with the first rake face in the radial direction and having a positive rake angle. The roughing end mill according to claim 1,
A luffing end mill, wherein the first rake face is linear in a cross-sectional view perpendicular to the axis. Roughing end mill according to claim 2,
A roughing end mill, wherein a rake angle of the first rake face is −45 ° or more in a cross-sectional view perpendicular to the axis. The roughing end mill according to claim 1,
The luffing end mill, wherein the first rake face has a concave curve shape in a cross-sectional view perpendicular to the axis. Roughing end mill according to claim 4,
The maximum diameter of the outer peripheral blade is a blade diameter D, and the distance from the top end of the convex portion along the radial direction to the bottom end of the concave portion is a nick depth H.
A luffing end mill, wherein a curvature of the first rake face is not less than (0.2 × blade diameter D) and not more than (1 / nick depth H) in a cross-sectional view perpendicular to the axis. A roughing end mill according to any one of claims 1 to 5,
The outer peripheral blade is along a virtual chord winding extending toward the opposite side to the end mill rotation direction from the distal end of the end mill body toward the proximal end side,
A luffing end mill, wherein a boundary line between the first rake face and the second rake face extends in parallel with the virtual string winding. A roughing end mill according to any one of claims 1 to 6,
The first rake face is formed in a region from the top end of the convex portion along the radial direction to the bottom end of the concave portion,
A roughing end mill, wherein a rake face at a bottom end of the recess is formed by the second rake face.

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