JP5402412B2 - Ball end mill and insert for ball end mill - Google Patents

Description

  The present invention relates to a ball end mill and an insert for a blade end replaceable ball end mill.

  2. Description of the Related Art Conventionally, a blade-type replaceable ball end mill in which a semi-disc-like insert is detachably attached to the tip of a rod-shaped tool body and a solid type ball end mill are known. In such a ball end mill, a plurality of arc-shaped cutting edges are formed on the tip edge so as to extend radially about the rotation axis. Generally, the inner peripheral ends of these cutting edges are located on the rotation axis. It is arranged at a front side in the tool rotation direction with respect to a straight line passing through the rotation axis in parallel with the tangent line of the cutting edge at the inner peripheral end in the rotation axis direction front end view, with a slight gap without reaching. As a result, the cutting edge is set so-called centering. Further, a chisel portion is formed between the inner peripheral ends of these cutting edges so that the flank faces of the cutting edges intersect to form a ridge shape. The chisel portion and the cutting blade that sandwiches the chisel portion are formed so as to be smoothly continuous, and have, for example, an arc shape when viewed from the side perpendicular to the rotation axis of the ball end mill.

However, since such a chisel portion is located at the center of the tip of the ball end mill, the cutting speed at the time of cutting is substantially zero, and the work surface of the work material is not cut without being used for cutting the work material. While rubbing, the surface roughness of the processed surface was reduced.
Therefore, for example, in the ball end mill described in Patent Document 1, a concave portion having a concave V shape in side view is formed without forming a chisel portion at the center of the tip so as to prevent the aforementioned rubbing. Yes.

Japanese Utility Model Publication No. 3-65614

However, the ball end mill as described in Patent Document 1 has the following problems.
That is, the mechanical strength at the tip edge may be reduced by forming a V-shaped recess. In addition, chips generated by cutting tend to accumulate in the recess, and the chips may damage the processed surface of the work material and reduce the surface roughness.

  Further, when manufacturing such a ball end mill, generally, for example, a grinding wheel having a disk shape and a cutting edge of the outer peripheral edge having a trapezoidal cross section is used. It was difficult to manufacture the portion in a V shape, which was not practical.

  The present invention has been made in view of such circumstances, and can improve the surface roughness of the processed surface of the work material, and can stably secure the processing accuracy and insert for a blade end replaceable ball end mill. The purpose is to provide.

In order to achieve the above object, the present invention proposes the following means.
That is, the present invention is a ball end mill in which a tip end of an end mill body rotated around an axis is provided with a cutting edge having a spherical shape with a rotation locus around the axis centered on the axis. A recess is formed in the center of the tip, which is recessed toward the rear end side in the axial direction with respect to the inner peripheral end of the cutting edge. A plurality of the cutting edges are provided, and an outer edge portion of the recess is connected to the end mill. Extending toward the rear end side of the main body, the recess includes a wall surface extending from the outer edge portion toward the rear end side in the axial direction, and a ridge line that intersects the wall surface and faces the front end side of the end mill main body , The ridgeline is characterized in that flank faces adjacent to the cutting edge around the axis intersect with each other in the recess .

According to the ball end mill according to the present invention, the concave portion which is retracted toward the rear end side in the axial direction from the inner peripheral end of the cutting edge is formed at the tip center of the tip portion of the end mill body. Thus, the surface roughness of the processed surface of the workpiece to be cut is increased by forming the recess at the center of the tip of the end mill body.

  Specifically, in the conventional ball end mill, the chisel portion is formed at the tip center of the end mill body so as to continue to the inner peripheral side of the cutting edge, so the cutting speed of the chisel portion becomes substantially zero, Machining was performed such that the chisel portion rubbed the work surface of the work material. In this case, the surface roughness of the processed surface of the work material is reduced, and the cutting resistance is increased. In addition, the rubbed processed surface may be work-hardened, affecting the finishing process in the subsequent process. On the other hand, according to the ball end mill of the present invention, problems such as rubbing, increased cutting resistance, work hardening and the like as described above do not occur.

Further, since the concave portion includes a wall surface extending from the outer edge portion toward the rear end side in the axial direction and a ridge line that intersects the wall surface and faces the front end side of the end mill body, for example, the concave portion is simply V-shaped in a side view. Compared to the case of forming in a shape or the like, the thickness at the tip of the end mill body can be ensured, and the mechanical strength of the tip is increased. As a result, it is possible to reliably prevent the occurrence of vibration during cutting or the early occurrence of chipping on the cutting edge, and stably ensure machining accuracy.

Furthermore, the recess formed in this way has a relatively shallow depth from the outer edge to the ridgeline , and chips generated by cutting are less likely to accumulate in the recess. Therefore, for example, when the concave portion is formed relatively deep, chips do not accumulate in the concave portion and the processing surface of the work material is not damaged. Therefore, the finishing accuracy of the processed surface is further increased.

Moreover, the ball end mill which concerns on this invention WHEREIN: The said ridgeline is good also as extending in the direction orthogonal to the said axis line.

According to the ball end mill according to the present invention, since the ridge line of the recess extends in a direction perpendicular to the axis, the depth in the ridge line is leveled as a whole, and the mechanical strength is more stable. As a result, the rotational balance around the axis in the recess is stabilized. In addition, it is easy to form the ridge line of the recess during manufacture.

  Moreover, the ball end mill which concerns on this invention WHEREIN: The opening width of the outer edge part of the said recessed part is good also as being set in the range of 0.1-0.5 mm.

  According to the ball end mill according to the present invention, since the opening width of the outer edge portion in the recess is set within the range of 0.1 to 0.5 mm, the surface roughness of the work surface of the work material to be cut is set. The processing accuracy is ensured while increasing. Further, even when the pick feed is set to the upper limit of the recommended conditions, the theoretical surface accuracy is sufficiently maintained.

  Specifically, when the opening width is set to be less than 0.1 mm, the inner peripheral end of the cutting edge disposed on the outer edge (that is, the end of the cutting edge on the axial line side) is too close to the axis, and the cutting speed Becomes substantially zero, and the processing surface is rubbed to reduce the surface roughness, and the rubbed processing surface may be work-hardened. In addition, when the opening width is set to exceed 0.5 mm, the inner peripheral edge of the cutting edge is greatly separated from the center of the tip, and the pick feed is set to the upper limit of the recommended condition. There is a risk that the surface accuracy may not be sufficiently maintained.

Moreover, the ball end mill which concerns on this invention WHEREIN: The depth from the outer edge part of the said recessed part to a ridgeline is good also as being set in the range of 5-30 micrometers.

According to the ball end mill according to the present invention, since the depth from the outer edge portion to the ridge line in the recess is set in the range of 5 to 30 μm, while reliably preventing chips from collecting in the recess, Cutting can be performed with high accuracy and stability over a long period of time.

That is, when the depth is set to be less than 5 μm, the tip of the end mill body wears as the cutting edge is cut and the depth of the recess becomes shallow, and the ridge line of the recess comes into contact with the processing surface at an early stage. As a result, the aforementioned rubbing may occur and the surface roughness of the processed surface may become unstable. Moreover, when the depth is set to exceed 30 μm, chips are likely to be accumulated in the recesses, and the chips may damage the processed surface of the work material.

  Further, in the ball end mill according to the present invention, a distance from an intersection of an imaginary line obtained by extending the cutting edge from the outer edge portion of the concave portion toward the axis line side and the axis line to the outer edge portion along the axial direction is It may be set to 2 μm or less.

  According to the ball end mill of the present invention, since the distance in the concave portion is set to 2 μm or less, the processing surface of the work material can be accurately formed into an R shape. That is, when the distance is set to exceed 2 μm, the processed surface of the work material becomes flat and a desired R shape may not be obtained.

  In the ball end mill according to the present invention, the wall surface is an inclined surface that gradually extends toward the rear end side in the axial direction from the outer edge portion toward the axial line side, and the inclined surface is inclined with respect to the axial line. It is good also as the angle to do within the range of 5-50 degrees.

  According to the ball end mill according to the present invention, the angle in the recess is set within a range of 5 to 50 °. The concave portion can be easily formed using a general grinding wheel.

  The present invention also relates to an insert for a blade end replaceable ball end mill that is detachably attached to an insert mounting seat formed at a tip of the end mill body in the ball end mill described above, and the insert body is formed in a flat plate shape. A blade and the recess are formed.

  According to the insert for a blade end replaceable ball end mill according to the present invention, the surface roughness of the processed surface of the work material is increased, and cutting can be performed with high accuracy and stability.

  According to the ball end mill and the insert for a blade end replaceable ball end mill according to the present invention, the surface roughness of the processed surface of the work material can be improved, and the processing accuracy can be secured stably.

It is a perspective view showing a blade tip exchange type ball end mill concerning one embodiment of the present invention. It is a perspective view which expands and shows the front-end | tip part of the blade-tip-exchange-type ball end mill of FIG. It is a perspective view which shows the insert which concerns on one Embodiment of this invention. It is a top view which shows the insert which concerns on one Embodiment of this invention. It is a front view which shows the insert which concerns on one Embodiment of this invention. It is a side view which shows the insert which concerns on one Embodiment of this invention. It is an enlarged view which shows the X section of FIG. It is an enlarged view which shows the X 'part of FIG. It is an enlarged view which shows the Y section of FIG.

  1 and 2 show an embodiment of a blade end replaceable ball end mill (ball end mill) according to the present invention, and FIGS. 3 to 9 show inserts (blade replaceable type) used in the blade replaceable ball end mill. 1 shows an embodiment of a ball end mill insert.

  As shown in FIG. 1, a blade end replaceable ball end mill 10 of the present embodiment has a tool body (end mill body) 1 having a substantially round bar shape or an elongated cylindrical shape centering on an axis O. The rear end side (upper right side in FIG. 1) is a cylindrical shank portion 2. The blade tip replaceable ball end mill 10 is rotated in the rotation direction T around the axis O when the shank portion 2 is mounted on the main spindle of the machine tool, and is used for cutting a work material. Further, the tool body 1 is tapered on the tip side of the shank portion 2, and the tip portion of the tool body 1 is substantially hemispherical with the center on the axis O.

  Further, a slit-like insert mounting seat 3 is formed at the distal end portion of the tool body 1 by cutting out so that a cross section including the axis O forms a “U” shape that opens to the distal end side. In addition, as shown in FIG. 2, a pair of sandwiching portions 4, 4 arranged opposite to each other with the axis O interposed at the distal end portion of the tool body 1 divided into two by such an insert mounting seat 3. Is formed. These sandwiching portions 4 and 4 each have a substantially semi-disc shape, and an insert 11 is detachably mounted between the inner surfaces facing each other.

  In addition, an insertion hole 4 </ b> A of the clamp screw 5 is formed so as to pass through one of these sandwiching portions 4, 4 so as to be orthogonal to the axis O. Further, a screw hole (not shown) into which the clamp screw 5 is screwed is formed on the other of the sandwiching portions 4 and 4 coaxially with the insertion hole 4A.

  Then, when the clamp screw 5 is tightened in a state where the insert 11 is mounted on the insert mounting seat 3, the sandwiching portions 4, 4 are brought closer to each other, and the outer surface of the insert 11 is The inner surfaces of the holding portions 4 and 4 are contacted and pressed. In this way, the insert 11 is firmly held at the tip of the tool body 1. Further, chip pockets 6 are respectively formed on the rear side in the rotational direction T of the outer peripheral surfaces of the sandwiching portions 4 and 4.

  As shown in FIGS. 3 to 6, the insert 11 attached to the insert mounting seat 3 of the tool body 1 has an insert body 12 made of a hard material such as cemented carbide. As shown in FIG. 4, the insert body 12 has a rear end surface 12A formed flat so that the rear end side (lower side in FIG. 4) is cut into a straight line by about 1/3 as shown in FIG. Except for this, it is a flat plate having a substantially circular shape.

  Further, the insert body 12 is located at the center in the thickness direction (vertical direction in FIGS. 5 and 6) and the width direction (horizontal direction in FIGS. 4 and 5) of the insert body 12 thus formed in a flat plate shape. And it is made into the reverse-inversion symmetric shape regarding the insert axis L orthogonal to the said rear end surface 12A.

  The insert 11 has a pair of side surfaces 12B, 12B facing the thickness direction of the insert body 12 facing the inner surfaces of the holding portions 4, 4 of the tool body 1, and a rear end surface 12A of the insert mounting seat 3 at the outermost surface. The insert mounting seat 3 is inserted into the insert mounting seat 3 in a posture toward the back, and the clamp screw 5 is screwed in as described above, so that the insert mounting seat 3 is mounted.

  The distance between the side surfaces 12B and 12B of the insert 11 is set slightly smaller than the distance between the inner surfaces of the holding portions 4 and 4 of the tool body 1, and the insert 11 is inserted into the insert mounting seat. 3, the opposing side surface 12 </ b> B and the inner surface of the holding portion 4 are in sliding contact with each other.

  Further, of the pair of side surfaces 12B, 12B of the insert body 12, the outer peripheral edge portion on the side facing the rotation direction T when being seated on the insert mounting seat 3 is cut so as to be recessed by one step in the thickness direction. The rake faces 13 and 13 are omitted. Further, strip-shaped flank surfaces 14 and 14 are formed so as to be adjacent to the rear sides of the rake surfaces 13 and 13 in the rotation direction T, respectively.

  Further, the intersecting ridge line portion between the rake face 13 and the flank face 14 has an arc shape having a center on the insert shaft L in the plan view and is gentle as a whole as shown in FIG. A pair of cutting edges 15, 15 having an S shape are formed at the leading edge of the insert body 12. Note that the radius of the arc formed by the cutting edge 15 is slightly larger than the radius of the hemisphere formed by the tip of the tool body 1. Further, the inner peripheral end of the cutting edge 15 is spaced slightly from the insert shaft L without reaching the insert shaft L, and is parallel to the tangent line of the cutting edge 15 at the inner peripheral end when viewed from the front end of the insert shaft L direction. With respect to the straight line which passes through L, it is arrange | positioned ahead of the rotation direction T, and, thereby, the cutting edge 15 is set to what is called a core rise.

  In a state where the insert 11 is mounted on the insert mounting seat 3 of the tool body 1, the insert shaft L and the axis O are made to coincide with each other, and the cutting edge 15 protrudes from the tip end portion of the tool body 1 and around the axis O. The rotation locus is formed in a spherical shape having a center on the axis O. Specifically, the cutting edge 15 of the insert 11 protrudes toward the distal end side and radially outward at the distal end portion of the tool body 1. Then, when the tool body 1 is rotated around the axis O, the cutting edge 15 is cut into the work material, and cutting is performed.

  Further, portions of the pair of side surfaces 12B, 12B of the insert body 12 other than the rake face 13 are formed in a planar shape parallel to each other and perpendicular to the thickness direction. The inner surfaces of the clamping parts 4 and 4 cut out by the chip pocket 6 in the tool body 1 are substantially equal.

  A mounting hole 16 through which the clamp screw 5 is inserted is formed between the side surfaces 12B and 12B so as to penetrate the insert body 12 in the thickness direction. This mounting hole 16 is opened to the side surface 12B, and when the insert body 12 is inserted into the insert mounting seat 3 and seated, it is coaxial with the insertion hole 4A of the holding portions 4 and 4 and the screw hole. Is arranged.

  Further, as shown in FIGS. 7 to 9, a recess 17 is formed in a region located on the insert shaft L on the outer surface of the distal end portion of the insert main body 12, that is, in the center of the distal end. As shown in a front view (front end view) in FIG. 9, the concave portion 17 includes a pair of flank surfaces 14 and 14 and a pair of cutting blades 15 that are opposed to each other across the insert shaft L at the front end center of the insert body 12. 15 is located. The recess 17 is formed to be recessed from the front end surface of the insert body 12 to the rear end side in the insert axis L direction, and as shown in FIGS. 7 and 8, the insert 17 is viewed from the thickness direction orthogonal to the insert axis L. It has a substantially isosceles trapezoidal shape that gradually narrows toward the rear end side in the axis L direction.

  The pair of cutting edges 15 are positioned on a pair of outer edge portions 18 whose inner peripheral ends are arranged in the concave portion 17, respectively, and are arranged so as to follow the outer peripheral surface of the insert body 12 from the outer edge portion 18. Each extends toward the end side. As shown in FIG. 9, the recess 17 gradually widens from the inner peripheral end of the cutting edge 15 (that is, the outer edge 18) toward the insert axis L from the inner peripheral end, and the tip of the insert body 12. A pair of inclined surfaces 19 having a substantially triangular shape in front view that is inclined so as to recede from the surface are provided. The inclined surface 19 forms a wall surface of the concave portion 17 and is formed to gradually extend from the outer edge portion 18 toward the rear end side in the axis O direction as it goes inward in the radial direction (axis O side).

  Further, the concave portion 17 continues to one flank 14A of the pair of flank surfaces 14 and 14, and intersects an inclined surface 19B connected to the inner peripheral end of the other cutting edge 15B of the pair of cutting blades 15 and 15. The bottom portion 20A has a substantially rectangular shape when viewed from the front. Further, the concave portion 17 is formed on the inclined surface 19A connected to the inner peripheral end of one of the pair of cutting edges 15 and 15 continuously from the other flank 14B of the pair of flank faces 14 and 14. It has a bottom surface portion 20 </ b> B that is substantially rectangular when viewed from the front. The bottom surface portion 20A and the bottom surface portion 20B are opposite to each other in inclination, and intersect with each other via a ridge line 20C passing through the insert axis L. The bottom surface portions 20A and 20B and the ridge line 20C are orthogonal to the insert axis L and extend in a direction perpendicular to the insert axis L along the ridge line 20C as a whole, and constitute the bottom surface 20 of the recess 17. Yes. That is, the bottom surface 20 is disposed so as to face the tip side in the direction of the axis O when the insert 11 is mounted on the tool body 1, and the inclined surfaces 19A, 19B are connected so as to connect the pair of inclined surfaces 19A, 19B. It intersects with 19B and extends in a direction orthogonal to the insert axis L.

  Moreover, as shown in FIG. 8, the distance between the outer edge parts 18 and 18 of the recessed part 17, ie, the opening width A of the outer edge parts 18 and 18, is set in the range of 0.1-0.5 mm. . Specifically, for example, when the diameter in the width direction of the insert 11 is φ10 mm, the opening width A is set to about 0.175 mm, and when the diameter is φ32 mm, the opening width A is set to about 0.30 mm.

  Further, the depth C from the outer edge 18 of the recess 17 to the ridge line 20C of the bottom surface 20 is set within a range of 5 to 30 μm. In the present embodiment, the depth C is set to about 9 μm.

  Further, the imaginary line S shown by a two-dot chain line in FIG. 8 in which the cutting edge 15 is extended from the outer edge portion 18 of the concave portion 17 toward the insert shaft L side, and the insert shaft L along the insert shaft L direction from the intersection point. The distance B to the outer edge portion 18 is set to 2 μm or less. In the present embodiment, the distance B is set to about 0.8 μm.

  Further, the angle α at which the inclined surface 19 of the recess 17 is inclined with respect to the insert axis L is set within a range of 5 to 50 °. In the present embodiment, the angle α is set to about 20 °.

  As described above, according to the blade tip replaceable ball end mill 10 and the insert 11 used therefor according to the present embodiment, the tip of the tool body 1 is attached to the center of the tip of the insert body 12 attached to the tip of the tool body 1. A recess 17 is formed corresponding to the axis O. By forming the recess 17 at the center of the tip in this way, the surface roughness of the processed surface of the work material to be cut is increased.

  Specifically, in the conventional insert, since the chisel portion is formed in the center of the tip of the insert body so as to be continuous with the cutting edge, the cutting speed of the chisel portion becomes substantially zero, and the chisel portion is covered. Processing was performed by rubbing the processed surface of the cutting material. In this case, the surface roughness of the processed surface of the work material is reduced, and the cutting resistance is increased. In addition, the rubbed processed surface may be work-hardened, affecting the finishing process in the subsequent process. On the other hand, according to the insert 11 of the present embodiment, since the concave portion 17 is formed at the center of the tip of the insert main body 12, problems such as rubbing, increased cutting resistance, and work hardening as described above do not occur.

Further, the concave portion 17 extends from the pair of outer edge portions 18, 18 so as to incline toward the rear end side in the axis O direction, and faces the tip end side in the axis O direction, and intersects the inclined surfaces 19A, 19B. In addition, the ridge line 20C of the bottom surface 20 extending so as to connect the inclined surfaces 19A and 19B is provided, so that the mechanical strength in the concave portion 17 is ensured. That is, the ridge line 20C of the bottom surface 20 of the recess 17 connects the inclined surfaces 19A and 19B, and a pair of cutting edges 15 extending from the outer edge portions 18 and 18 on the front end side in the axis O direction of the inclined surfaces 19A and 19B. , 15 so as to bridge the inner peripheral ends of the insert body, for example, in contrast to the case where the concave portion 17 is not provided with a bottom surface and is simply formed into a concave V-shape in a side view. The thickness at the tip portion of 12 can be secured, and the mechanical strength of the tip portion is enhanced. As a result, it is possible to reliably prevent the occurrence of vibration during cutting and the early occurrence of chipping in the cutting edge 15 and ensure stable machining accuracy.

  Further, the depth 17 of the recess 17 formed in this way is relatively shallow, so that chips generated by the cutting process are hardly accumulated in the recess 17. Therefore, for example, when the concave portion 17 is formed relatively deep, chips do not accumulate in the concave portion 17 and the processing surface of the work material is not damaged. Therefore, the finishing accuracy of the processed surface is further increased.

Further, since the ridge 20C of the bottom surface 20 of the recess 17 is formed to extend perpendicularly to the insert axis L, are leveled throughout the depth C of the ridge 20C of the bottom surface 20, the mechanical strength of the above is more stable And the rotational balance around the axis O in the recess 17 is stabilized. Further, it is easy to form the ridge line 20C of the bottom surface 20 of the concave portion 17 during manufacturing.

  Moreover, since the opening width A of the outer edge 18 in the recess 17 is set within a range of 0.1 to 0.5 mm, the processing accuracy is improved while increasing the surface roughness of the processing surface of the work material to be cut. Is secured. Further, even when the pick feed is set to the upper limit of the recommended conditions, the theoretical surface accuracy is sufficiently maintained.

  Specifically, when the opening width A is set to be less than 0.1 mm, the inner peripheral end of the cutting edge 15 disposed on the outer edge 18 is too close to the axis O, and the cutting speed becomes substantially zero, and the machining surface The surface roughness may be reduced, and the rubbed processed surface may be work-hardened. When the opening width A is set to exceed 0.5 mm, the inner peripheral end of the cutting edge 15 is greatly separated from the center of the tip, and the pick feed is set to the upper limit of the recommended condition. The theoretical surface accuracy may not be sufficiently maintained.

Moreover, since the depth C from the outer edge 18 in the recess 17 to the ridgeline 20C of the bottom surface 20 is set within a range of 5 to 30 μm, while reliably preventing chips from collecting in the recess 17, Cutting can be performed with high accuracy and stability over a long period of time.

That is, when the depth C is set to less than 5μm, the ridge depth C of the leading edge of the insert body 12 and cutting edge wear recess 17 becomes shallow, bottom 20 of the recess 17 in accordance with cutting 20C comes into contact with the processed surface at an early stage, the above-mentioned rubbing may occur, and the surface roughness of the processed surface may not be stable. In addition, when the depth C is set to exceed 30 μm, chips are likely to accumulate in the concave portion 17 and the chips may damage the processing surface of the work material.

  In addition, since the distance B in the concave portion 17 is set to 2 μm or less, the processed surface of the work material can be accurately formed into an R shape. That is, when the distance B is set to exceed 2 μm, the processed surface of the work material becomes flat and a desired R shape may not be obtained.

  Moreover, since the said angle (alpha) of the recessed part 17 is set in the range of 5-50 degrees, for example, the disk shape is used and the edge of the outer periphery part uses the general grinding wheel with the cross-sectional trapezoid shape. Thus, the concave portion 17 can be easily formed.

In addition, this invention is not limited to the above-mentioned embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.
For example, the concave portion 17 is provided with the inclined surface 19 as its wall surface. However, the present invention is not limited to this, and the wall surface extends from the outer edge portion 18 toward the axis O toward the rear end side in the axis O direction. It may be formed so as to extend in parallel and to be orthogonal to the ridgeline 20C of the bottom surface 20.

In the present embodiment, the ridge line 20C of the bottom surface 20 of the recess 17 extends in a direction orthogonal to the axis O direction. However, the present invention is not limited to this. For example, the ridge line 20C of the bottom surface 20 is the axis line. It may be formed slightly inclined with respect to the direction orthogonal to the O direction.

In the present embodiment, the pair of cutting edges 15 are provided. However, the present invention is not limited to this, and three or more cutting edges 15 may be provided. In this case, three or more outer edge portions 18 are arranged in the concave portion 17 corresponding to the inner peripheral ends of the three or more cutting edges 15. The concave portion 17 intersects the inclined surfaces 19 with inclined surfaces (wall surfaces) 19 extending from the at least two outer edge portions 18 to the rear end side in the axis O direction. It is good also as providing the ridgeline 20C of the bottom face 20 extended so that it may connect.

  In the present embodiment, the blade end replaceable ball end mill 10 is used as the ball end mill. However, the present invention is not limited to this, and the present invention is applied to other solid type and blade end brazing type ball end mills. Applicable.

1 Tool body (end mill body)
3 Insert mounting seat 10 Blade end replaceable ball end mill (ball end mill)
11 Insert (Insert for insertable ball end mill)
12 Insert body 15 Cutting edge 17 Recessed portion 18 Outer edge portion 19 Inclined surface (wall surface)
20 Bottom
20C Ridge line A Opening width of the outer edge of the recess B Distance from the intersection of the imaginary line and the axis extending the cutting edge from the outer edge of the recess toward the axial side to the outer edge along the axial direction C From the outer edge of the recess Depth to ridge line L Insert shaft (axis)
O Axis line S Virtual line that extends the cutting edge to the axis side α Angle that the inclined surface is inclined with respect to the axis line

Claims (7)

A ball end mill in which a tip end of an end mill body rotated around an axis is provided with a cutting edge having a spherical shape with a rotation locus around the axis centered on the axis,
A concave portion is formed at the tip center of the tip portion so as to recede from the inner peripheral end of the cutting edge toward the rear end side in the axial direction. A plurality of the cutting blades are provided and an outer edge portion of the concave portion is provided. Extending toward the rear end side of the end mill body,
The recess includes a wall surface extending from the outer edge portion toward the rear end side in the axial direction, and a ridge line that intersects the wall surface and faces the front end side of the end mill body ,
In the ball end mill , the ridge line is formed such that flank faces adjacent to the cutting edge around the axis intersect in the recess . The ball end mill according to claim 1,
The ball end mill, wherein the ridge line extends in a direction orthogonal to the axis. The ball end mill according to claim 1 or 2,
The ball end mill, wherein an opening width of an outer edge portion of the concave portion is set within a range of 0.1 to 0.5 mm. The ball end mill according to any one of claims 1 to 3,
A ball end mill characterized in that a depth from an outer edge portion of the concave portion to a ridge line is set within a range of 5 to 30 μm. The ball end mill according to any one of claims 1 to 4,
The distance from the intersection of the imaginary line that extends the cutting edge from the outer edge of the recess toward the axis and the axis, to the outer edge along the axial direction is set to 2 μm or less. Features a ball end mill. The ball end mill according to any one of claims 1 to 5,
The wall surface is an inclined surface that gradually extends toward the rear end side in the axial direction as it goes from the outer edge portion toward the axial line side,
An angle at which the inclined surface is inclined with respect to the axis is set in a range of 5 to 50 °. In the ball end mill according to any one of claims 1 to 6, an insert for a blade end replaceable ball end mill that is detachably attached to an insert mounting seat formed at a tip portion of the end mill body,
An insert for a blade end replaceable ball end mill, wherein the insert blade and the recess are formed in a flat insert body.

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