JP7189439B2 - Indexable end mills, end mill bodies and cutting inserts - Google Patents

Description

The present invention provides an insert body of the same shape and size having at least two cutting edges in a first insert mounting seat and a second insert mounting seat formed at the tip of an end mill body that rotates around an axis. The present invention relates to an indexable end mill to which a first cutting insert and a second cutting insert are detachably attached, an end mill main body of such an indexable end mill, and a cutting insert.

As such a tip-exchangeable end mill, for example, Patent Document 1 discloses an end mill having two cutting edges of the same shape and the same shape in a first insert mounting seat and a second insert mounting seat formed at the tip of an end mill body. A first cutting insert and a second cutting insert each having a large insert body are detachably attached, and the insert body has two cutting edges, a major cutting edge and a minor cutting edge, each of which has a convex curved shape. The cutting edge is composed of a cutting edge and a linear cutting edge, and has a substantially leaf-shaped plate shape in which the convex curved cutting edge and the linear cutting edge of the main cutting edge and the minor cutting edge are alternately arranged. A replaceable ball end mill is described.

Here, the arc-shaped cutting edge portion of the major cutting edge is longer in the circumferential direction than the arc-shaped cutting edge portion of the minor cutting edge, and the linear cutting edge portion of the major cutting edge is the linear cutting edge of the minor cutting edge. It is shorter than the part, and the major and minor cutting edges are asymmetrical. The first cutting insert has a major cutting edge extending from the vicinity of the rotation axis at the tip of the end mill body to the outer peripheral side, and the second cutting insert has a minor cutting edge extending from the tip to the proximal end of the end mill body. The main cutting edge and the minor cutting edge are arranged so as to extend to the outer peripheral side at a position retracted to the side so that the rotational trajectories of the major cutting edge and the minor cutting edge overlap on the rotational trajectory about the rotation axis.

Further, in the indexable end mill described in Patent Document 1, the seating surfaces of the insert bodies of the first cutting insert and the second cutting insert extend in parallel with a mounting hole through which the clamp screw is inserted. A first groove portion and a second groove portion (key groove) are formed so as to be present, and the first groove portion and the second groove portion are aligned with the bottom surfaces of the first insert mounting seat and the second insert mounting seat. The first cutting insert and the second cutting insert are respectively fitted to the first projection and the second projection (key) formed so as to extend in parallel with the screw hole into which the clamp screw is screwed. A cutting insert is positioned.

In such an indexable end mill, a first cutting insert and a second cutting insert of the same shape and size are attached to the first insert mounting seat and the second insert mounting seat for cutting. can be performed, management of the cutting insert is facilitated, and since only one mold is required for manufacturing the cutting insert, the manufacturing cost of the cutting insert can be reduced.

JP-A-11-197933

By the way, in the indexable end mill described in Patent Document 1, as shown in FIGS. are through grooves that open to the flank surfaces of the major cutting edge and the minor cutting edge and pass through the seating surface, and the lengths in the extending direction of the first and second grooves are They are equal and the distances from the mounting holes are also equal. Therefore, the first protrusion and the second protrusion of the first insert mounting seat and the second insert mounting seat, into which the first groove and the second groove are fitted, are also the first protrusion and the second protrusion. and the second projection are equal in length in the extending direction, and are also equal in distance from the screw hole.

However, the lengths in the direction in which the first groove portion and the second groove portion of the insert body of the first cutting insert and the second cutting insert extend are equal, and the intervals between the mounting holes are also equal to each other. In addition, if the lengths in the extending direction of the first protrusion and the second protrusion are equal to each other and the distances between the screw holes are also equal to each other, the first groove in the first cutting insert will be the first groove. The second groove is fitted to the first protrusion of the first insert mounting seat, or the first groove of the second cutting insert is fitted to the second protrusion of the first insert mounting seat. is fitted to the second protrusion of the second insert mounting seat and the second groove is fitted to the first protrusion of the second insert mounting seat, so that the insert main body is fitted to the insert mounting seat There is a risk that it may be installed in the wrong direction, resulting in incorrect installation.

If the insert main body is erroneously mounted on the insert mounting seat in this way, for example, the insert main body used for cutting with the main cutting edge as the first cutting insert is replaced with the second insert mounting seat as the second cutting insert. When trying to use an unused minor cutting edge for cutting, the used major cutting edge is used for cutting, or conversely, the minor cutting edge is used for cutting as a second cutting insert. When an attempt is made to use the unused main cutting edge for cutting by mounting the inserted insert body as the first cutting insert to the first insert mounting seat as the first cutting insert, the used minor cutting edge is used for cutting. As a result, cutting is performed with a used cutting edge that has been damaged due to wear or the like, which may lead to an increase in cutting resistance or loss of cutting efficiency. Also, when the cutting insert is mounted on the first insert mounting seat and the second insert mounting seat in such a direction that the minor cutting edge is used for cutting, cutting can be performed at the tip of the indexable end mill. As a result, it becomes impossible to obtain the cutting edge diameter accuracy inherent in the indexable end mill, resulting in uncut portions on the machined surface of the work material.

The present invention has been made under such a background. By preventing erroneous mounting of the cutting insert in the wrong direction, as a first effect, the original cutting edge of the indexable end mill can be improved. An indexable end mill that can obtain diameter accuracy and, as a second effect, can prevent an increase in cutting resistance and a decrease in cutting efficiency due to the use of used cutting edges for cutting. , and an end mill body and cutting insert for such an indexable end mill.

In order to solve the above problems and achieve the above objects, the indexable end mill of the present invention has a first insert mounting seat and a first An indexable end mill in which a first cutting insert and a second cutting insert each having an insert body having the same shape and size and having at least two cutting edges are detachably attached to two insert mounting seats, The insert body includes a seating surface in close contact with the bottom surfaces of the first insert mounting seat and the second insert mounting seat, a mounting hole opening in the center of the seating surface and penetrating the insert body, and a mounting hole. A first groove portion and a second groove portion extending in parallel to each other on the seating surface with the opening of the hole therebetween are provided, and the length in the extending direction of the first groove portion is equal to that of the second groove portion. The length in the extending direction of the groove is shorter than the length in the extending direction, and the bottom surfaces of the first insert mounting seat and the second insert mounting seat are provided with screw holes into which clamp screws inserted through the mounting holes are screwed. The first insert mounting seat is accommodated in the second groove portion when the mounting hole in the insert body of the first cutting insert is overlapped with the screw hole and the seating surface is brought into close contact with the bottom surface. The second insert mounting seat includes at least a first convex portion extending such that the mounting surface of the second insert mounting seat overlaps the screw hole with the mounting hole in the insert body of the second cutting insert. At least a second protrusion extending so as to be accommodated in the second groove when in close contact with the bottom surface is provided, and the length in the direction in which the first protrusion extends and the second protrusion are provided. The length in the extending direction of the projection is longer than the length in the extending direction of the first groove.

Further, the end mill body of the present invention is an end mill body of such an indexable end mill, wherein the bottom surfaces of the first insert mounting seat and the second insert mounting seat are inserted into the mounting holes of the insert body. The first insert mounting seat has a threaded hole into which a clamp screw is screwed, and the first insert mounting seat has the mounting hole in the insert body of the first cutting insert overlapping the screw hole so that the seating surface is brought into close contact with the bottom surface. The second insert mounting seat includes at least a first convex portion extending so as to be accommodated in the second groove portion when the cutting insert is closed, and the second insert mounting seat corresponds to the mounting hole in the insert body of the second cutting insert. is superimposed on the screw hole and the seating surface is brought into close contact with the bottom surface; The length in the extending direction and the length in the extending direction of the second protrusion are longer than the length in the extending direction of the first groove.

Further, the cutting insert of the present invention is a cutting insert having an insert body having at least two cutting edges attached to the first insert mounting seat and the second insert mounting seat of the indexable end mill as described above. The insert body includes a seating surface in close contact with the bottom surfaces of the first insert mounting seat and the second insert mounting seat, a mounting hole opening in the center of the seating surface and penetrating the insert body, A first groove and a second groove extend parallel to each other on the seating surface with the opening of the mounting hole therebetween, and the length of the first groove in the extending direction is equal to the length of the first groove. 2 is shorter than the length in the extending direction of the groove.

In the indexable end mill of the present invention configured by mounting such cutting inserts as the first cutting insert and the second cutting insert to the end mill body as described above, the first insert mounting of the end mill body The length in the extending direction of the first protrusion formed on the bottom surface of the seat and the length in the extending direction of the second protrusion formed on the bottom surface of the second insert mounting seat Since it is longer than the length in the direction in which the first groove formed in the seating surface of the insert body extends, when the first cutting insert is attached to the first insert mounting seat, the seating surface of the first cutting insert is Even if the first protrusion of the first insert mounting seat is mistakenly accommodated in the first groove in It rides on the first protrusion having a long length in the extending direction.

Similarly, when the second cutting insert is attached to the second insert mounting seat, the second protrusion of the second insert mounting seat is erroneously accommodated in the first groove on the seating surface of the second cutting insert. Even if it is attempted, the seating surface of the insert body left by the first groove having a short length in the direction of extension rides on the second convex portion having a length in the direction of extension. Therefore, even if an attempt is made to mount the insert body so that the mounting hole of the insert body overlaps the screw hole on the bottom face of the insert mounting seat, the seating surface of the insert body cannot be brought into close contact with the bottom face, thereby preventing erroneous mounting of the cutting insert. . For this reason, in the case of an indexable ball end mill, for example, the first and second cutting inserts will not be installed in the direction in which the minor cutting edge is used for cutting, and the original cutting edge of the indexable end mill will not be used. The accuracy of the cutting edge diameter can be ensured, and the used cutting edge of the cutting insert can be prevented from being reused, thereby avoiding an increase in cutting resistance and a decrease in cutting efficiency.

Here, the wall surface of the first groove portion on the mounting hole side and the wall surface of the second groove portion on the mounting hole side extend parallel to each other in a bottom view viewed from a direction facing the seating surface. In addition, it is desirable that the distances from the center line of the mounting holes are equal to each other. With this configuration, the thicknesses of the first and second grooves and the mounting hole become equal, so it is possible to prevent unstable mounting of the insert main body due to this unevenness in thickness. becomes.

Moreover, it is desirable that the second groove portion has a narrow portion in which the groove width becomes narrower from one end side to the other end side in the extending direction of the second groove portion. As a result, on the other end side where the groove width of the narrow portion is narrow, the thickness of the cutting insert can be ensured to disperse the stress and improve the strength.

Further, at least one of the first convex portion and the second convex portion is arranged in a portion accommodated in the narrow portion of the second groove portion in a direction other than the extending direction of the second groove portion. It is desirable that the width increases from the end side to the one end side. As a result, it is possible to increase the mounting rigidity of at least one of the first convex portion and the second convex portion against the load during cutting, and to reliably prevent the cutting insert from shifting. .

Furthermore, the second insert mounting seat is formed by overlapping the mounting hole in the insert body of the second cutting insert with the second convex portion accommodated in the second groove portion on the screw hole, thereby forming the seating surface. is preferably provided with a third convex portion extending so as to be accommodated in the first groove portion when the bottom surface is brought into close contact with the bottom surface. Similarly, the first insert mounting seat is formed by stacking the mounting hole in the insert body of the first cutting insert having the first convex portion accommodated in the second groove portion on the screw hole and forming the seating surface. is preferably provided with a fourth convex portion extending so as to be accommodated in the first groove portion when the bottom surface is brought into close contact with the bottom surface. This also prevents the first and second cutting inserts mounted on the first and second insert mounting seats from shifting.

Further, in order to make the length in the extending direction of the first groove portion shorter than the length in the extending direction of the second groove portion as described above, the first groove portion is provided on one side of the seating surface. The second groove is formed in the shape of a blind groove that opens only at the ridge, and the second groove is formed in the shape of a through groove that traverses the seating surface and opens at the two ridges of the seating surface. good too. In this case, it is particularly easy to finish form the wall surface of the through-groove-like second groove portion with a grinding tool.

In addition, when the indexable end mill of the present invention is an indexable ball end mill as described in Patent Document 1, the insert body faces the opposite side of the seating surface and faces the end mill body. A rake face directed in the direction of rotation and a flank extending around the rake face and the seating surface are provided. The two cutting edges each having an arc-shaped cutting edge portion extending in an arc shape in plan view and a linear cutting edge portion extending in contact with one end of the arc-shaped cutting edge portion The blade portion and the linear cutting edge portion are alternately positioned in the circumferential direction of the rake face, and one of the two cutting edges is a major cutting edge and the other is a minor cutting edge, The arcuate cutting edge portion of the major cutting edge is formed to have a longer circumferential length with a radius equal to that of the arcuate cutting edge portion of the minor cutting edge, and the first cutting insert is configured to The arc-shaped cutting edge portion of the cutting blade has the center of the arc of the arc-shaped cutting edge portion on the axis in the rotational locus about the axis, and extends from the axis of the tip of the end mill body to the outer peripheral side of the rear end. The second cutting insert is attached to the first insert mounting seat so as to form a shape, and the arc-shaped cutting edge portion of the minor cutting edge moves along the rotational trajectory of the first cutting insert about the axis. is mounted on the second insert mounting seat so as to overlap with the hemisphere formed by the rotational locus of the circular arc-shaped cutting edge portion of the main cutting edge and extend from a position away from the axis line at the tip of the end mill body to the outer peripheral side of the rear end. may have been

According to such an indexable end mill (ball end mill), similar to the indexable ball end mill described in Patent Document 1, one type of cutting insert having the same shape and size is used as the first cutting insert and the second cutting insert. Since the cutting insert can be attached to the first insert mounting seat and the second insert mounting seat and cut, the management of the cutting insert is easy, and there is only one mold for manufacturing the cutting insert. , the manufacturing cost of the cutting insert can be reduced. Since the insert body of such a cutting insert is likely to be attached to the insert mounting seat in the wrong direction, it is effective to employ the configuration of the present invention. Moreover, since it is possible to avoid cutting only by the arc-shaped cutting edge portion of the minor cutting edge, which is short in the circumferential direction, it is possible to maintain the original cutting edge diameter accuracy of the indexable end mill. It is also possible to avoid leaving uncut portions on the machined surface of the cutting material.

Moreover, the indexable end mill of the present invention can also be applied to an indexable end mill in which a groove-shaped nick is formed on the cutting edge. In this case, the insert body has a rake face facing away from the seating surface and directed in the direction of rotation of the end mill body, and a flank extending around the rake face and the seating surface. , an arcuate cutting edge portion extending in an arcuate shape in a plan view viewed from the direction facing the rake surface and an arcuate cutting edge portion in contact with one end of the arcuate cutting edge portion The first cutting edge and the second cutting edge each having a linear cutting edge portion extending in the direction of the edge and another linear cutting edge portion extending so as to contact the other end are connected to the other linear cutting edge portion. and the arcuate cutting edge portion and the linear cutting edge portion are formed in order in the circumferential direction of the rake face, and the rake face includes the first cutting edge and the second cutting edge. Groove-shaped nicks that reach the blades and open to the flank face are formed, and the first cutting edge and the second cutting edge extend around the center line of the mounting hole except for the nicks. and the first cutting insert and the second cutting insert have a basic shape with 180° rotational symmetry, and the first cutting edge of the first cutting insert in the rotational trajectory about the axis and the basic shape of the second cutting edge of the second cutting insert are overlapped and attached to the first insert mounting seat and the second insert mounting seat, and the first cutting edge and the The nicks reaching the second cutting edge may be formed so as not to overlap each other in the locus of rotation about the axis.

According to such an indexable end mill, cutting can be performed by attaching one type of cutting insert having the same shape and size as the first cutting insert and the second cutting insert as described above, and managing the cutting inserts. can be simplified and the manufacturing cost of the cutting insert can be reduced, and elongated chips and wide chips generated by the first cutting edge and the second cutting edge can be reliably divided. The insert body of such a cutting insert is also likely to be attached to the insert mounting seat in the wrong direction. It is not possible to obtain the original accuracy of the cutting edge diameter of the end mill, leaving uncut portions on the machined surface of the work material. , is also effective.

As described above, according to the present invention, it is possible to prevent erroneous attachment of the cutting insert to the insert mounting seat, and reduce the cutting resistance caused by the erroneous reuse of the used cutting edge for cutting due to erroneous attachment. In addition to preventing an increase in cutting efficiency and a decrease in cutting efficiency, it is also possible to secure the original cutting edge diameter accuracy of indexable end mills and prevent uncut surfaces from being left uncut. .

1 is a perspective view showing a first embodiment of a cutting insert of the present invention; FIG. FIG. 2 is a plan view of the embodiment shown in FIG. 1 viewed from a direction facing the rake face; FIG. 2 is a bottom view of the embodiment shown in FIG. 1 viewed from a direction facing the seating surface; FIG. 3 is a side view seen in the direction of an arrow A in FIG. 2; FIG. 3 is a side view seen in the direction of an arrow B in FIG. 2; FIG. 3 is a side view seen in the direction of an arrow C in FIG. 2; FIG. 3 is a side view seen in the direction of an arrow D in FIG. 2; 1 is a perspective view showing a tip portion of a first embodiment of an end mill body of the present invention; FIG. 9 is a front view of the distal end of the embodiment shown in FIG. 8; FIG. FIG. 10 is a plan view seen in the direction of an arrow A in FIG. 9; FIG. 10 is a side view seen in the direction of an arrow B in FIG. 9; FIG. 10 is a bottom view as seen in the direction of arrow C in FIG. 9; FIG. 10 is a side view seen in the direction of an arrow D in FIG. 9; The indexable end mill of the present invention in which the cutting insert of the embodiment shown in FIGS. 1 to 7 is attached to the first insert mounting seat and the second insert mounting seat of the end mill shown in FIGS. Fig. 2 is a perspective view showing the tip of the first embodiment of the indexable ball end mill (however, illustration of the clamp screw is omitted). Figure 15 is a front view of the embodiment shown in Figure 14; FIG. 16 is a plan view viewed in the direction of arrow A in FIG. 15 (however, illustration of clamp screws is omitted). 15. It is a side view of the arrow B direction view in FIG. FIG. 16 is a bottom view as viewed in the direction of arrow C in FIG. 15 (however, illustration of clamp screws is omitted). FIG. 16 is a side view seen in the direction of arrow D in FIG. 15; FIG. 5 is a plan view of a second embodiment of the cutting insert of the present invention, viewed from the direction facing the rake face; FIG. 21 is a bottom view of the embodiment shown in FIG. 20 viewed from a direction facing the seating surface; FIG. 21 is a side view seen in the direction of an arrow A in FIG. 20; FIG. 21 is a side view seen in the direction of an arrow B in FIG. 20; FIG. 21 is a side view seen in the direction of an arrow C in FIG. 20; FIG. 21 is a side view seen in the direction of an arrow D in FIG. 20; Indexable end mill (index indexable radius end mill with nicks) and end mill of the present invention in which the cutting inserts of the embodiment shown in FIGS. FIG. 11 is a perspective view showing a second embodiment of the main body; Figure 27 is a front view of the embodiment shown in Figure 26; FIG. 28 is a plan view seen in the direction of arrow A in FIG. 27; FIG. 28 is a side view of FIG. 27 viewed in the direction of an arrow B; FIG. 28 is a side view seen in the direction of an arrow C in FIG. 27; FIG. 31 is a perspective view showing the positional relationship between two cutting inserts in the indexable end mill of the embodiment shown in FIGS. 26 to 30; 32 is a perspective view of the two cutting inserts whose positional relationship is shown in FIG. 31, viewed from the direction facing the rake face of the right cutting insert in FIG. 31; FIG. FIG. 26 is a bottom view of a modification of the second embodiment shown in FIGS. 20 to 25, viewed from the direction facing the seating surface; 34 is a perspective view showing the positional relationship between two cutting inserts when the modified cutting insert shown in FIG. 33 is attached to the end mill main body of the indexable end mill (the indexable radius end mill with nicks). FIG.

1 to 7 show a cutting insert according to a first embodiment of the invention. 8 to 13 show the tip of the end mill main body 11 of the indexable end mill (index indexable ball end mill) to which the cutting insert of the first embodiment is detachably attached, and FIG. 19 is an embodiment of an indexable end mill (indexable ball end mill) of the present invention in which two cutting inserts of the first embodiment are detachably attached to the insert mounting seat 12 of the end mill body 11. shows the tip of the

The cutting insert of this embodiment is thus a cutting insert for an indexable ball end mill, and includes an insert body 1 made of a hard material such as cemented carbide. The insert body 1 is formed in a leaf-like plate shape in plan view as shown in FIG. The upper surface of the insert body 1 is the leaf-shaped rake surface 2 as described above, and the lower surface facing the opposite side of the rake surface 2 is also leaf-shaped and substantially similar to the rake surface 2, which will be described later. A flat seating surface 3 is formed in close contact with the bottom surface of the insert mounting seat 12 except for the groove. A flank surface 4 is formed between the rake surface 2 and the seating surface 3 and extends circumferentially.

At the intersection ridgeline between the rake face 2 and the flank face 4, arcuate cutting edge portions 5a and 6a extending arcuately as shown in FIG. Two cutting edges each having linear cutting edge portions 5b and 6b extending in contact with the arcuate cutting edge portions 5a and 6a are connected to the arcuate cutting edge portions 5a and 6a and the linear cutting edge portions 5b and 6b. They are formed alternately in the circumferential direction of the rake face 2 . One of the two cutting edges, the first cutting edge, is the major cutting edge 5 and the other second cutting edge is the minor cutting edge 6 .

In addition, the flank 4 is inclined toward the inner peripheral side of the insert body 1 as it goes from the rake face 2 to the seating surface 3 side, and the cutting insert of this embodiment is a positive type cutting insert. . Further, a mounting hole 7 having a circular cross section is formed through the insert body 1 at the center of the rake surface 2 and the seating surface 3. It is formed so as to decrease in diameter toward the three sides.

Here, in the plan view, the arcuate cutting edge portion 5a of the main cutting edge 5 has a substantially 1/4 arcuate shape. On the other hand, the arcuate cutting edge portion 6a of the minor cutting edge 6 has the same radius as the arcuate cutting edge portion 5a of the major cutting edge 5, but the length in the circumferential direction is equal to that of the major cutting edge 5. It is shorter than the portion 5a, that is, formed in an arc shape shorter than a quarter arc. Along with this, the linear cutting edge portion 5b of the major cutting edge 5 is made shorter than the linear cutting edge portion 6b of the minor cutting edge 6. As shown in FIG. That is, the insert body 1 of the cutting insert of this embodiment is not 180° rotationally symmetrical about the center line E of the mounting hole 7, but asymmetrical.

The linear cutting edge portions 5b and 6b of the major cutting edge 5 and the minor cutting edge 6 are the same as the arcuate cutting edge portion 5a of the major cutting edge 5 and the linear cutting edge portion 6b of the minor cutting edge 6 in the above-described plan view. from the first end 2a of the rake face 2 where the two intersect to the second end of the rake face 2 where the linear cutting edge 5b of the major cutting edge 5 and the arcuate cutting edge 6a of the minor cutting edge 6 intersect They extend closer to each other toward the portion 2b. These first and second end portions 2a and 2b are chamfered so as to intersect the arcuate cutting edge portions 5a and 6a and the linear cutting edge portions 5b and 6b of the major cutting edge 5 and the minor cutting edge 6 at an obtuse angle. formed in the shape of The first end 2a is positioned closer to the seating surface 3 than the second end 2b.

Further, the arcuate cutting edge portions 5a and 6a of the major cutting edge 5 and the minor cutting edge 6 move away from the seating surface 3 side as they separate from the respective linear cutting edge portions 5b and 6b, and then move toward the seating surface 3 side. , and the point where the convex curve formed by these arc-shaped cutting edge portions 5a and 6a becomes convex farthest from the seating surface 3 (the most projected point from the seating surface 3) ) are the major cutting edge convexity point and the minor cutting edge convexity point, respectively. The linear cutting edge portions 5b and 6b of the major cutting edge 5 and the minor cutting edge 6 also have arcuate cutting edge portions as shown in FIGS. It is in contact with the convex curve formed by the portions 5a and 6a and extends in a substantially straight line approaching the seating surface 3 side as the distance from the arcuate cutting edge portions 5a and 6a increases.

Here, in the main cutting edge 5, a rotation axis (a first cutting insert, which will be described later, is attached to the end mill body 11 and is parallel to the linear cutting edge portion 5b and passes through the center of the arcuate cutting edge portion 5a in plan view). In the cross section along the rotation axis of the rotation locus of the main cutting edge 5 around the axis O) of the end mill body 11 in the attached state, the arc-shaped cutting edge extends from the center of the arc-shaped cutting edge portion 5a of the rotation axis a portion extending toward the end opposite to the point of contact with the linear cutting edge portion 5b in the portion 5a (first end 2a side; in the case of an indexable end mill, the tip end side of the end mill body 11, which will be described later); A straight line connecting the center and the most convex point of the major cutting edge intersects at an angle within the range of 43° to 47°. In this embodiment, this angle is 45°.

The minor cutting edge 6 also has an arc-shaped cutting edge that coincides with the center of the arc-shaped cutting edge portion 5a of the major cutting edge 5 in plan view in a state of being attached to the end mill body 11 as a second cutting insert to be described later. In a cross section along the rotation axis of the rotation locus of the minor cutting edge 6 around the rotation axis (also the axis O of the end mill main body 11 to be described later) passing through the center of the cutting edge 6a and parallel to the linear cutting edge 6b, From the center of the arcuate cutting edge 6a of the rotating shaft to the end of the arcuate cutting edge 6a opposite to the point of contact with the linear cutting edge 6b (second end 2b side). In the type end mill, the portion extending toward the tip end side of the end mill body 11 (to be described later) and the straight line connecting the center and the most convex point of the minor cutting edge intersect at an angle within the range of 43° to 47°. . In this embodiment, this angle is also 45°.

Around the opening of the mounting hole 7 in the central portion of the rake face 2, there is a substantially elliptical shape in plan view that protrudes in a direction away from the seating surface 3 more than the major cutting edge 5 and the minor cutting edge 6. A protrusion 2c is formed. The upper end surface of this protrusion 2c is a flat surface parallel to the seating surface 3, and the mounting hole 7 opens to the upper end surface of this protrusion 2c. Further, the outer peripheral surface of the protrusion 2c is inclined toward the inner side of the rake face 2 toward the upper end surface. Further, the rake face 2 extends toward the seating surface 3 as it moves away from the major cutting edge 5 and the minor cutting edge 6 and extends toward the inner side of the rake face 2, and then forms a concave curved surface on the outer peripheral surface of the protrusion 2c. are connected.

Furthermore, the flanks 4 connected to the linear cutting edge portions 5b and 6b of the major cutting edge 5 and the minor cutting edge 6 are formed in an inclined flat shape as described above. On the rake face 2 side, the flank 4 connected to the arcuate cutting edge portions 5a and 6a of the major cutting edge 5 and the minor cutting edge 6 extends in the circumferential direction of the insert body 1 along these arcuate cutting edge portions 5a and 6a. However, on the seating surface 3 side of the flank 4 of the arcuate cutting edge portion 5a of the main cutting edge 5, there is formed a plane portion 4a that is inclined in a plane shape as shown in FIGS. ing.

Further, as shown in FIGS. 3, 4, 6 and 7, grooves 8 are formed in the seating surface 3. As shown in FIGS. Here, in the present embodiment, as shown in FIG. They are formed so as to extend in parallel on opposite sides with the opening of the hole 7 in between. The first groove 8A is formed closer to the first end 2a of the rake face 2 than the opening of the mounting hole 7, and the second groove 8B is formed closer to the second end 2b of the rake face 2. It is

These grooves 8 are formed in a substantially rectangular cross-section perpendicular to the direction in which the grooves 8 extend and are flattened in the direction in which the mounting holes 7 extend. It has first and second wall surfaces 8a and 8b facing each other, and a bottom surface 8c parallel to the seating surface 3 extending between the first and second wall surfaces 8a and 8b. The first wall surface 8a of each groove 8 faces the first end 2a of the rake face 2, and the second wall surface 8b faces the second end 2b of the rake face 2. As shown in FIG.

Here, the first wall surface 8a of the first groove portion 8A on the side of the mounting hole 7 and the second wall surface 8b of the second groove portion 8B on the side of the mounting hole 7 are viewed from the direction facing the seating surface 3. As shown in FIG. 3 in bottom view, they extend parallel to each other, and the distances d from the center line E of the mounting hole 7 are equal to each other. Further, the intersection ridges between the first and second wall surfaces 8a and 8b and the seating surface 3 are chamfered with convex curved surfaces, and the corners where the first and second wall surfaces 8a and 8b and the bottom surface 8c intersect are concave. It is formed in a curved shape.

At least one of the second wall surface 8b of the first groove portion 8A opposite to the mounting hole 7 and the first wall surface 8a of the second groove portion 8B opposite to the mounting hole 7 is a seating surface. It may be an inclined surface that inclines toward the side opposite to the mounting hole 7 as it goes to the 3 side, and the first wall surface 8a of the first groove 8A on the mounting hole 7 side and the second groove 8B At least one of the second wall surface 8b on the mounting hole 7 side and the second wall surface 8b may be an inclined surface that slopes toward the mounting hole 7 side toward the seating surface 3 side.

In this way, when extending in the shape of an inclined surface, the attachment hole 7 between the first wall surface 8a of the first groove portion 8A on the attachment hole 7 side and the second wall surface 8b of the second groove portion 8B on the attachment hole 7 side. The distance d from the center line E is the distance between the lines of intersection between the first and second wall surfaces 8a and 8b and the bottom surface 8c. is formed in a concave curved shape, it is the interval of intersection lines when the planar first and second wall surfaces 8a and 8b and the bottom surface 8c are extended.

The first groove portion 8A opens to the flank 4 continuing to the linear cutting edge portion 6b of the minor cutting edge 6 and does not open to the flank 4 continuing to the arcuate cutting edge portion 5a of the major cutting edge 5. It is formed like a groove. Further, the first and second wall surfaces 8a and 8b of the first groove portion 8A extend parallel to each other in the bottom view, and the groove width of the first groove portion 8A is equal to that of the arcuate cutting edge of the main cutting edge 5. It is constant except for the end on the part 5a side.

The end portion of the first groove portion 8A on the side of the arc-shaped cutting edge portion 5a of the main cutting edge 5 extends from the bottom surface 8c to the seating surface 3 so as to form a concave curved surface. It is formed in the shape of a convex curve parallel to the arc-shaped cutting edge portion 5a of the main cutting edge 5 or in the shape of an oblique side obliquely crossing the first and second wall surfaces 8a and 8b of the first groove portion 8A. The groove portion 8A is formed in a substantially trapezoidal shape when viewed from the direction facing the seating surface 3. As shown in FIG.

On the other hand, in the present embodiment, the second groove portion 8B includes both the flank 4 continuous with the linear cutting edge 5b of the major cutting edge 5 and the flank 4 continuous with the arcuate cutting edge 6a of the minor cutting edge 6. It is formed in the shape of a through-groove opening to the outside. Therefore, the length N1 in the extending direction of the first groove portion 8A formed like a blind groove is made shorter than the length N2 in the extending direction of the second groove portion 8B formed like a through groove. ing.

Furthermore, in this embodiment, the second groove portion 8B has a narrow portion 9 in which the groove width becomes narrower from one end side to the other end side in the direction in which the second groove portion 8B extends. Here, in the present embodiment, the side of the flank 4 connected to the linear cutting edge portion 5b of the major cutting edge 5 is one end side of the second groove portion 8B, and the arcuate cutting edge portion 6a of the minor cutting edge 6 The continuous flank 4 side is the other end side.

Further, as shown in FIG. 3, the entire second groove portion 8B is the narrow portion 9 in this embodiment. In the present embodiment, the width of the narrow portion 9 is made constant from one end side to the other end side of the second groove portion 8B. That is, the first and second wall surfaces 8a and 8b of the second groove portion 8B are formed so as to approach each other linearly from one end side to the other end side in the bottom view.

Furthermore, the opening of the second groove portion 8B to the flank 4 that continues to the arc-shaped cutting edge portion 6a of the minor cutting edge 6 is located at the linear cutting edge portion of the minor cutting edge 6 from the convex point of the minor cutting edge. It is located on the 6b side. Specifically, in the bottom view, a straight line connecting the most convex point of the minor cutting edge and the center of the arc formed by the arcuate cutting edge portion 6a of the minor cutting edge 6 and the linear cutting edge portion of the minor cutting edge 6 A straight line (not shown) connecting the end of the intersection ridge (excluding the chamfered portion) of the first wall surface 8a of the second groove portion 8B facing the 6b side and the flank 4 toward the seating surface 3 side and the above-mentioned center and the first crossing angle is in the range of 5° to 60°.

The groove width W1 (not shown) at the other end of the narrow portion 9 (the other end of the second groove portion 8B in this embodiment) is the width of the groove portion (second groove portion 8B) having the narrow portion 9. 0.05×r to 0.18 with respect to the radius r (not shown) of the arc-shaped cutting edge portion (arc-shaped cutting edge portion 6a of the minor cutting edge 6) located on the other end side as viewed from the seating surface 3 side xr, for example, 1 mm to 7 mm. However, if the shape of the circular arc-shaped cutting edge 6a viewed from the seating surface 3 side is deviated from the circular arc, a virtual arc that is closest to the deviated shape is drawn, and this virtual , the radius r will be obtained from the arc of .

On the other hand, the groove width W2 (not shown) at one end of the narrow portion 9 satisfies W2>W1, and the groove portion (second groove portion 8B) having the narrow width portion 9 has an arc-shaped cutting portion located on the other end side. 0.10×r to 0.10×r to 0.10×r to 0.10×r to 0.10×r to 0.10×r to a radius r of the blade portion (arc-shaped cutting edge portion 6a of the minor cutting edge 6) in a bottom view viewed from the seating surface 3 side or a plan view viewed from the rake face 2 side. In the range of 30×r, the length R (not shown) of the linear cutting edge portion 5b of the main cutting edge 5 in the above plan view or bottom view is in the range of 0.10×R to 0.32×R. It is said that

Note that when the first and second wall surfaces 8a and 8b extend linearly in a bottom view viewed from the direction facing the seating surface 3, the groove widths W1 and W2 are equal to those of the first and second wall surfaces 8a and 8b. is the width in the direction perpendicular to the bisector of the straight line formed by the wall surfaces 8a and 8b, one groove wall surface (for example, the first wall surface 8a) is curved, When the wall surface 8b) of 2 is linear, it is the width in the direction perpendicular to the linear groove wall surface.

Here, the insert body 1 of the cutting insert made of hard material such as cemented carbide is manufactured according to the basic steps of powder metallurgy technology. That is, when the insert body 1 is made of a cemented carbide, a granular granulated powder containing tungsten carbide powder and cobalt powder as main components and, if necessary, chromium, tantalum, etc. as subcomponents is used to mold the mold. Perform powder press molding using

The press-molded body thus obtained is sintered for a predetermined time in a sintering furnace controlled to an appropriate atmosphere and temperature, whereby a sintered body that will become the insert body 1 can be manufactured. The basic shape of the insert body 1 is reflected by the design of the die, and the detailed shape of the insert body 1 is obtained by die molding. Furthermore, in order to improve the precision of the cutting edge shape of the insert body 1, grinding processing using a grinding wheel may be performed as necessary.

The cutting insert of the first embodiment is detachably attached to the insert mounting seat 12 formed at the tip of the end mill body 11 of the first embodiment shown in FIGS. 8 to 13 as described above. 14 to 19 constitute the first embodiment of the indexable end mill (indexable ball end mill) of the present invention.

The end mill main body 11 is formed of a metal material such as steel, and the tip portion thereof has a cylindrical shape centered on the axis O on the base end side, and has a base end portion centered on the axis O on the tip end side. It has a convex hemispherical shape with a radius equal to that of a cylinder. In the indexable end mill of the present embodiment, the end mill main body 11 is rotated around the axis O in the end mill rotation direction T and sent out in a direction intersecting the axis O, whereby the cutting edge is attached to the insert mounting seat 12. The insert cuts the work material.

Here, in this embodiment, two tip pockets 13 are formed by notching the outer circumference of the end mill main body 11, and inserts are attached to the bottom faces of these tip pockets 13 facing the end mill rotation direction T, respectively. Seats 12 are circumferentially spaced and formed opposite each other. Two cutting inserts of the same shape and size based on the first embodiment are mounted on these two insert mounting seats 12 as first and second cutting inserts 1A and 1B, respectively.

These insert mounting seats 12 have a flat bottom surface 12a oriented in the end mill rotation direction T except for projections, which will be described later, and an inner peripheral side of a distal end extending from the bottom surface 12a in the end mill rotation direction T and facing the outer peripheral side of the end mill main body 11. wall surface 12b and a wall surface 12c on the outer peripheral side of the rear end facing the outer peripheral side of the distal end. The wall surfaces 12b and 12c are formed in a planar shape that inclines outwardly of the insert mounting seat 12 as the distance from the bottom surface 12a increases. The planar flank 4 connected to the linear cutting edge portions 5b and 6b of the blade 6 and the flat portion 4a of the flank 4 connected to the arcuate cutting edge portions 5a and 6a on the side of the seating surface 3 can be brought into contact. .

A concave portion 12d is formed between the wall surfaces 12b and 12c to avoid contact with the curved flank 4 of the insert body 1. As shown in FIG. Further, the bottom surface 12a is formed with a screw hole 12e into which a clamp screw (not shown) inserted through the mounting hole 7 of the insert body 1 is screwed. The center line of this screw hole 12e is connected to the linear cutting edge portions 5b and 6b of the major cutting edge 5 and the minor cutting edge 6 with the seating surface 3 of the insert body 1 seated on the bottom surface 12a as described above. With the flat portion 4a of the flank 4 on the seating surface 3 side connected to the flat flank 4 and the arcuate cutting edges 5a and 6a in contact with the wall surfaces 12b and 12c, the mounting hole 7 of the insert body 1 is removed. It is slightly eccentric from the center line E toward the concave portion 12d.

8 to 11, the first insert mounting seat 12A of the two insert mounting seats 12 is formed so as to cut the tip portion of the end mill main body 11 to a range including the axis O on the tip side. ing. A first cutting insert 1A having the insert main body 1 of the cutting insert of the first embodiment is mounted on the first insert mounting seat 12A so that the arcuate cutting edge portion 5a of the main cutting edge 5 is positioned inside the tip of the end mill main body 11. Extending from the vicinity of the axis O on the circumferential side to the outer peripheral side of the rear end, it is positioned on the convex hemisphere having the center of the arc of the arc-shaped cutting edge portion 5a on the axis O, and the linear cutting edge of the main cutting edge 5 The blade portion 5b is attached so as to be positioned on a cylindrical surface centered on the axis O in contact with the convex hemisphere.

Therefore, the planar flank 4 continuous with the linear cutting edge portion 6b of the minor cutting edge 6 of the first cutting insert 1A is brought into contact with the wall surface 12b of the first insert mounting seat 12A, and the wall surface 12c is in contact with the wall surface 12c. The flat portion 4a of the flank 4 of the arc-shaped cutting edge portion 6a of the minor cutting edge 6 of the first cutting insert 1A is brought into contact.

Further, the bottom surface 12a of the first insert mounting seat 12A is accommodated in the second groove portion 8B formed in the seating surface 3 of the first cutting insert 1A, and the wall surface of the second groove portion 8B abuts. A possible first convex portion 14A protrudes between the screw hole 12e and the wall surface 12c, and extends from the outer peripheral surface of the tip portion of the end mill body 11 toward the concave portion 12d to the front of the concave portion 12d. It is formed to extend at intervals. A fourth convex portion 14D accommodated in the first groove portion 8A of the first cutting insert 1A is formed on the end mill main body 11 on the tip side of the screw hole 12e of the bottom surface 12a of the first insert mounting seat 12A. is formed so as to extend with a gap between the outer peripheral surface of the tip portion of and the wall surface 12b.

Here, the first convex portion 14A has a substantially rectangular cross-section perpendicular to the direction in which the first convex portion 14A extends and is flattened in the end mill rotation direction T, and the entirety is a narrow portion 9. With respect to the second groove portion 8B, the overall width increases from the other end side to the one end side (from the inner peripheral side to the outer peripheral side of the end mill body 11) in the direction in which the second groove portion 8B extends. It is formed to be

However, the width of the first protrusion 14A (the width in the direction orthogonal to the direction in which the first protrusion 14A extends) contacts the first protrusion 14A in the direction in which the second groove 8B extends. position (the width in the direction orthogonal to the direction in which the second groove portion 8B extends), and the protrusion height of the first convex portion 14A from the bottom surface 12a is also the first cutting insert. It is made slightly smaller than the depth of the second groove portion 8B from the seating surface 3 of 1A.

On the other hand, as shown in FIGS. 8, 9, 12 and 13, the second insert mounting seat 12B of the two insert mounting seats 12 is located slightly outward from the axis O on the tip end side of the end mill body 11. formed from a distance. A second cutting insert 1B having the insert main body 1 of the cutting insert of the first embodiment is attached to the second insert mounting seat 12B so that the arcuate cutting edge portion 6a of the minor cutting edge 6 extends from the axis O. The arc-shaped cutting edge portion 5a of the main cutting edge 5 of the first cutting insert 1A is positioned on the convex hemisphere where the arc-shaped cutting edge portion 5a of the first cutting insert 1A is located from a distant position, and the linear cutting edge portion 6b of the minor cutting edge 6 is positioned on the first The cutting insert 1A is mounted so as to be positioned on the cylindrical surface where the linear cutting edge portion 5b of the main cutting edge 5 of the cutting insert 1A is located.

Therefore, the planar flank 4 continuous with the linear cutting edge portion 5b of the main cutting edge 5 of the second cutting insert 1B is brought into contact with the wall surface 12b of the second insert mounting seat 12B, and the wall surface 12c is in contact with the wall surface 12c. The flat portion 4a of the flank 4 of the arcuate cutting edge portion 5a of the main cutting edge 5 of the second cutting insert 1B is brought into contact.

Further, on the bottom surface 12a of the second insert mounting seat 12B, a second projection 14B is formed on the tip side of the screw hole 12e, and a third protrusion 14B is formed between the screw hole 12e and the wall surface 12c. A convex portion 14C is formed. These second and third protrusions 14B and 14C also extend from the outer peripheral surface of the tip of the end mill body 11 toward the inner peripheral side, and the second protrusion 14B extends toward the wall surface 12b of the second insert mounting seat 12B. The third protrusion 14C is formed to extend to the front of the recess 12d of the second insert mounting seat 12B with a space therebetween. there is Therefore, the second protrusion 14B is accommodated in the second groove 8B of the second cutting insert 1B and abuts thereon, and the third protrusion 14C is accommodated in the first groove 8A of the second cutting insert 1B. abut.

Further, the second and third protrusions 14B and 14C also have a substantially rectangular cross-section perpendicular to the direction in which the second and third protrusions 14B and 14C extend, which is flattened in the end mill rotation direction T, Of these, the second convex portion 14B is formed in the direction in which the second groove portion 8B extends, whereas the entire second groove portion 8B of the second cutting insert 1B that abuts thereon is the narrow portion 9. It is formed so that it becomes wider as a whole as it goes from the other end side to the one end side (from the outer peripheral side to the inner peripheral side of the end mill main body 11). The width of the third protrusion 14C is constant along the direction in which the third protrusion 14C extends.

Furthermore, the widths of the second and third protrusions 14B and 14C (the widths in the direction orthogonal to the direction in which the second and third protrusions 14B and 14C extend) are also the same as the second and first grooves 8B and 8A. Slightly wider than the width at the position where it abuts on the second and third protrusions 14B and 14C in the extending direction (the width in the direction perpendicular to the extending direction of the second and first grooves 8B and 8A) made smaller. Also, the protrusion heights of the second and third projections 14B and 14C from the bottom surface 12a of the second insert mounting seat 12B are also the same as the second and first groove portions 8B from the seating surface 3 of the second cutting insert 1B. It is slightly smaller than the depth of 8A.

The length L1 in the extending direction of the first protrusion 14A formed on the bottom surface 12a of the first insert mounting seat 12A and the second length L1 formed on the bottom surface 12a of the second insert mounting seat 12B The length L2 in the extending direction of the convex portion 14B is the length in the extending direction of the first groove portion 8A formed in the seating surface 3 of the insert body 1 of the first and second cutting inserts 1A and 1B. length N1.

Here, in the bottom view seen from the direction facing the seating surface 3 as described above, the end portion of the main cutting edge 5 on the side of the arc-shaped cutting edge portion 5a in the first groove portion 8A A first groove formed in a substantially trapezoidal shape by forming a convex curve parallel to the arcuate cutting edge portion 5a or in the shape of an oblique side obliquely crossing the first and second wall surfaces 8a and 8b of the first groove portion 8A. The length N1 in the extending direction of the groove portion 8A is such that the second wall surface 8b of the first groove portion 8A has a convex curved shape or It is the length up to the part where it starts to bend in the shape of the hypotenuse.

On the other hand, the length L2 in the extending direction of the second convex portion 14B of the second insert mounting seat 12B, as shown in FIG. It becomes the length of the facing side 14a. Also, the length L1 in the extending direction of the first projection 14A formed on the bottom surface 12a of the first insert mounting seat 12A is, as shown in FIG. This is the length of the side surface 14b facing the rear end side.

The first and second cutting inserts 1A and 1B are seated on the first and second insert mounting seats 12A and 12B in the correct orientation as described above, and have inverted truncated conical heads. When the clamp screw is inserted through the mounting hole 7 and screwed into the screw hole 12e, the center line of the screw hole 12e is slightly eccentric toward the recess 12d from the center line of the mounting hole 7 of the insert body 1. , the first and second cutting inserts 1A and 1B are respectively pressed against the recess 12d side as described above.

At this time, in the first insert mounting seat 12A, the plane of the flank 4 connecting to the linear cutting edge portion 6b of the minor cutting edge 6 of the first cutting insert 1A and the flank surface 4 connecting to the arcuate cutting edge portion 6a The portion 4a is pressed against the wall surfaces 12b and 12c, respectively. In addition, in the second insert mounting seat 12B, the flank 4 continuous with the linear cutting edge portion 5b of the main cutting edge 5 of the second cutting insert 1B is pressed against the wall surface 12b, thereby The flat portion 4a of the flank 4 that continues to the blade portion 5a is pressed against the wall surface 12c.

Along with this, the second groove portion 8B of the first cutting insert 1A abuts against the first convex portion 14A of the first insert mounting seat 12A from the tip end side of the end mill body 11 . Therefore, the second wall surface 8b of the second groove portion 8B of the first cutting insert 1A abuts against the side surface 14a of the end mill body 11 facing the distal end side of the first protrusion 14A, and the second groove portion A small gap is provided between the first wall surface 8a in 8B and the side surface 14b of the first protrusion 14A facing the rear end side of the end mill body 11. As shown in FIG.

Also, in the second insert mounting seat 12B, the second and first grooves 8B and 8A of the second cutting insert 1B are formed in the second and third projections 14B and 14C from the tip end side of the end mill body 11. abut. Therefore, the first wall surfaces 8a of the second and first grooves 8B and 8A abut on the side surfaces 14a of the end mill body 11 facing the tip side of the second and third protrusions 14B and 14C, respectively. 2. A small gap is provided between the second wall surface 8b of the first grooves 8B and 8A and the side surface 14b of the second and third projections 14B and 14C facing the rear end side of the end mill body 11. .

In this manner, the first and second cutting inserts 1A and 1B are seated on the first and second insert mounting seats 12A and 12B in the correct orientation, and the first to third protrusions 14A to 14C are seated on the first to third protrusions 14A to 14C. 1. By abutting the second grooves 8A and 8B, it is possible to prevent the insert body 1 from shifting due to the load during cutting.

By the way, if it is attempted to mount the insert body 1 to the insert mounting seat 12 in the wrong direction instead of the correct direction, for example, the insert body 1 should be attached to the first insert mounting seat 12A and the mounting hole 7 to the screw hole 12e. , the arc-shaped cutting edge 6a of the minor cutting edge 6 extends from the inner peripheral side of the front end of the end mill body 11 to the outer peripheral side of the rear end. , the first groove portion 8A in the seating surface 3 of the insert body 1 faces.

However, since the length L1 in the direction in which the first protrusion 14A extends is longer than the length N1 in the direction in which the first groove 8A extends, the first protrusion 14A is formed in the first groove 8A. 14A, the seating surface 3 of the insert body 1 without the first groove 8A rides on the first projection 14A.

Similarly, the insert main body 1 is placed on the second insert mounting seat 12B, and the mounting hole 7 is overlapped with the screw hole 12e so that the arc-shaped cutting edge portion 5a of the main cutting edge 5 extends from the tip inner peripheral side of the end mill main body 11 to the rear end outer peripheral side. If an attempt is made to mount it in the wrong direction so as to extend to the side, the first groove 8A on the seating surface 3 of the insert body 1 will face the second protrusion 14B of the second insert mounting seat 12B.

However, since the length L2 in the extending direction of the second convex portion 14B is also longer than the length N1 in the extending direction of the first groove portion 8A, the first groove portion 8A does not have the second convex portion. 14B, the seating surface 3 of the insert body 1 without the first groove 8A rides on the second projection 14B.

As described above, in the indexable end mill (indexable ball end mill), the end mill main body 11 and the cutting insert configured as described above, the mounting hole 7 of the insert main body 1 and the screw hole of the bottom surface 12a of the insert mounting seat 12 are oriented in the wrong direction. Even if it is attempted to overlap the insert body 12e and attach it, the seating surface 3 of the insert body 1 cannot be brought into close contact with the bottom surface 12a. Therefore, erroneous mounting of the cutting insert can be prevented, and the used cutting edge of the cutting insert will not be used again for cutting by mistake, resulting in an increase in cutting resistance due to the dull cutting edge. It is possible to avoid that the cutting efficiency is reduced. Moreover, in the first cutting insert 1A and the second cutting insert 1B, since the minor cutting edge 6 having a short circumferential length of the arc-shaped cutting edge portion 6a is not used for cutting, the cutting edge The blade diameter accuracy of the original cutting edges (major cutting edge 5 and minor cutting edge 6) of the replaceable end mill can be ensured, and the occurrence of uncut portions on the machined surface of the workpiece can be avoided.

In this embodiment, the first wall surface 8a of the first groove portion 8A of the insert body 1 on the side of the mounting hole 7 and the second wall surface 8b of the second groove portion 8B on the side of the mounting hole 7 are the seating surfaces. 3 are parallel to each other in a bottom view viewed from the direction opposite to 3, and the distance d from the center line E of the mounting hole 7 is made equal to each other. Therefore, the thicknesses between the first groove portion 8A and the second groove portion 8B in the insert body 1 and the mounting hole 7 can be made equal to each other. It is possible to prevent the attachment to the seat 12 from becoming unstable.

Furthermore, in the present embodiment, the second groove portion 8B has a narrow portion 9 in which the groove width becomes narrower from one end side to the other end side in the extending direction of the second groove portion 8B. . Therefore, according to the present embodiment, the thickness of the insert body 1 can be ensured on the other end side where the groove width of the narrow portion 9 is narrow, and the stress due to the cutting load can be dispersed. Strength can be improved.

Furthermore, while the second groove portion 8B of the insert body 1 has the narrow portion 9, in this embodiment, the first protrusion 14A of the first insert mounting seat 12A and the first protrusion 14A of the first insert mounting seat 12A In the portion where the second convex portion 14B of the second insert mounting seat 12B is accommodated in the narrow portion 9 of the second groove portion 8B, from the other end side to the one end side in the extending direction of the second groove portion 8B. It is formed so that it becomes wider as it goes.

Therefore, in the first projection 14A and the second projection 14B, it is possible to increase the mounting rigidity against the load acting during cutting, and to reliably prevent the cutting insert from slipping. In this embodiment, both the first convex portion 14A of the first insert mounting seat 12A and the second convex portion 14B of the second insert mounting seat 12B extend from the second groove portion 8B. Although it is formed so that it becomes wider as it goes from the other end side to the one end side in the direction, it is sufficient that at least one side is formed so as to be widened in this way.

Furthermore, in the present embodiment, the second insert mounting seat 12B is configured so that the mounting hole 7 in the insert body 1 of the second cutting insert 1B having the second convex portion 14B accommodated in the second groove portion 8B is the second insert mounting seat 12B. A third protrusion 14C extends to be accommodated in the first groove 8A when the seating surface 3 is brought into close contact with the bottom surface 12a by overlapping the screw hole 12e of the insert mounting seat 12B. Similarly, the first insert mounting seat 12A also has a mounting hole 7 in the insert main body 1 of the first cutting insert 1A having the first protrusion 14A accommodated in the second groove 8B. A fourth convex portion 14D extends so as to be accommodated in the first groove portion 8A when the seating surface 3 is brought into close contact with the bottom surface 12a by overlapping the screw hole 12e. Therefore, for example, even if the first and second protrusions 14A and 14B of the first and second insert mounting seats 12A and 12B are not formed wide as described above, the first and second insert mounting A shift movement of the first and second cutting inserts 1A, 1B attached to the seats 12A, 12B can be prevented.

Further, in this embodiment, the first groove portion 8A of the insert body 1 is formed in a blind groove shape that opens only to one edge portion of the seating surface 3, and the second groove portion 8B is formed so as to cover the seating surface 3. It is formed in the shape of a through-groove that traverses and opens at the two edge portions of the seating surface 3, so that the length N1 in the direction in which the first groove portion 8A extends is the length of the extension of the second groove portion 8B. It is shorter than the length of the direction. Therefore, it becomes easy to finish form the first wall surface 8a and the second wall surface 8b of the second groove portion 8B with a grinding tool.

Furthermore, the indexable end mill of the present embodiment is an indexable ball end mill, and the insert body 1 has a rake face 2 that faces the opposite side of the seating surface 3 and is oriented in the end mill rotation direction T, and this rake face 2 and a flank 4 extending around the seating surface 3, and an arc-shaped portion is formed on the intersection ridge between the rake face 2 and the flank face 4 when seen from the direction facing the rake face 2 in plan view. Two cutting edges (major cutting edge 5 and The minor cutting edge 6) is formed by alternately arranging arcuate cutting edge portions 5a, 6a and linear cutting edge portions 5b, 6b in the circumferential direction of the rake face 2. The cutting edge portion 5a has a radius equal to that of the arc-shaped cutting edge portion 6a of the minor cutting edge 6 and is formed to have a longer length in the circumferential direction.

In the first cutting insert 1A, the arc-shaped cutting edge portion 5a of the main cutting edge 5 has its center on the axis O in the rotational trajectory around the axis O, and extends from the axis O at the tip of the end mill main body 1 to the rear end outer periphery. The second cutting insert 1B is attached to the first insert mounting seat 12A so as to form a hemispherical shape extending laterally. The second insert overlaps with the hemisphere formed by the rotational locus of the arcuate cutting edge portion 5a of the main cutting edge 5 of the cutting insert 1A of No. 1 and extends from a position away from the axis O at the tip of the end mill main body 1 to the outer peripheral side of the rear end. It is attached to the mounting seat 12B.

According to such an indexable end mill (ball end mill), cutting inserts having one type of insert body 1 of the same shape and size are used as the first cutting insert 1A and the second cutting insert 1B, and the first insert is mounted. It can be mounted on the seat 12A and the second insert mounting seat 12B for cutting.

For this reason, the management of the cutting insert becomes easy, and when the insert body 1 is manufactured by powder press molding using the above-described mold, only one mold is required, so the manufacturing cost of the cutting insert can be reduced. In such a cutting insert for an indexable ball end mill, it is easy to mount the insert main body 1 in the insert mounting seat 12 in the wrong direction. is.

Next, FIGS. 20 to 25 show an insert body 21 of a cutting insert according to a second embodiment when the present invention is applied to an indexable radius end mill with nicks, and FIGS. , shows the second embodiment of the indexable end mill of the present invention in which two cutting inserts of the second embodiment are mounted on the insert mounting seat 32 and the second embodiment of the end mill main body 31, 31 and 32 show the positional relationship between two cutting inserts in the indexable end mill of this second embodiment. The parts common to those of the cutting insert and the indexable end mill of the first embodiment shown in FIGS.

In the cutting insert of the second embodiment, the insert body 21 is provided with two cutting edges 22, and these cutting edges 22 are provided with an arcuate cutting edge portion 22a and a linear cutting edge portion 22b. Although common to the first embodiment, the circumferential lengths of the arc-shaped cutting edge portions 22a of the two cutting edges 22 are equal to each other, and are substantially 1/4 arc-shaped, and these arc-shaped cutting edges The lengths of the linear cutting edge portions 22b extending in contact with one end of the portion 22a (the end portion on the counterclockwise side of the mounting hole 7 in FIG. 20) are also made equal.

In the cutting insert of the second embodiment, the other end of the arc-shaped cutting edge portion 22a (the end portion on the clockwise direction side around the mounting hole 7 in FIG. 20) is also provided on the arc-shaped cutting edge portion 22a. Another linear cutting edge portion 22c extending in contact therewith is formed. The lengths of these other linear cutting edge portions 22c are also made equal between the two cutting edges 22 and are shorter than the linear cutting edge portion 22b. Further, the other linear cutting edge portion 22c extends in a direction perpendicular to the linear cutting edge portion 22b or in a direction that intersects the linear cutting edge portion 22b at an angle slightly smaller than 90° when viewed from the direction facing the rake face 2. .

In addition, in the cutting insert of the second embodiment, these two cutting edges 22 extend in the counterclockwise direction around the mounting hole 7 when viewed from the direction facing the rake face 2. A cutting edge portion 22c, an arc-shaped cutting edge portion 22a, and a linear cutting edge portion 22b are positioned in order in the circumferential direction of the rake face 2 and formed. Therefore, the insert body 21 of the cutting insert of the second embodiment has a 180° rotationally symmetrical shape with respect to the mounting hole 7 in plan view facing the rake face 2 except for the nick 10 described below. Moreover, the two cutting edges 22 are formed on a plane parallel to the seating surface 3 except for the nick 10 in this embodiment, and do not have the most convex point as in the first embodiment.

Furthermore, in the insert main body 21 of the cutting insert of the second embodiment, the rake face 2 is formed with a groove-like nick 10 that reaches the cutting edge 22 and opens to the flank face 4 . In this embodiment, the nick 10 is formed in the shape of a concave groove by notching the rake face 2 in the shape of a concave curve such as a concave arc when viewed from the direction facing the flank face 4 . The distance between and is gradually increased toward the inner side of the rake face 2, and is formed so as to rise from the rake face 2 before reaching the upper end surface of the protrusion 2c.

A valley bottom line that passes through the most recessed position M on the seating surface 3 side of the nick 10 and connects a portion with a small distance from the seating surface 3 toward the inside of the rake surface 2 is a plan view facing the rake surface 2. , extending substantially perpendicular to the cutting edge. The boundary between the nick 10 and the rake face 2 is rounded to form a convex surface along the opening to the flank face 4 .

Further, a plurality (two) of nicks 10 are formed on each of the two cutting edges 22 at positions where they do not overlap when the insert body 21 of the cutting insert is rotated 180° around the mounting hole 7. . Of these two cutting edges 22, the first cutting edge 22A (the cutting edge 22 facing the lower right side in FIG. 20) has a plurality of nicks 10 formed only on the rake face 2 of the arcuate cutting edge portion 22a. It is open on the flank 4 at the bottom, and is not formed on the linear cutting edge 22b or the other linear cutting edge 22c.

In the second cutting edge 22B (the cutting edge 22 facing the upper left in FIG. 20), one of the plurality of (two) nicks 10 is formed on the rake face 2 of the arcuate cutting edge portion 22a, and the other One is formed at the contact point between the arc-shaped cutting edge portion 22a and the linear cutting edge portion 22b. In the first and second cutting edges 22A and 22B, the intervals between the nicks 10 in the circumferential direction of the arcuate cutting edge portion 22a are substantially equal to each other.

Furthermore, also in this second embodiment, the seating surface 3 of the cutting insert is capable of coming into contact with the protrusion 33 protruding from the bottom surface of the insert mounting seat 32 formed on the end mill main body 31 of the indexable radius end mill. A groove portion 8 having wall surfaces is formed so as to open to the flank surface 4 of the insert body 21 . Here, the opening of the nick 10 to the flank 4 does not entirely overlap the opening of the groove 8 to the flank 4 as shown in FIG. placed in position.

Also in the second embodiment, two grooves 8 are formed in the seating surface 3. Of these two grooves 8, the first groove 8A on the lower side in FIG. A blind groove that opens only to the flank 4 of the linear cutting edge portion 22b of the cutting edge 22B, and the upper second groove portion 8B in FIG. 22b and a through groove that opens to the flank surface 4 of the arc-shaped cutting edge portion 22a of the second cutting edge 22B. is shorter than the length N2 in the extending direction. Furthermore, the second groove portion 8B as a whole has a groove width that narrows as it goes from one end of the first cutting edge 22A on the flank surface 4 side toward the other end of the second cutting edge 22B on the flank surface 4 side. A narrow width portion 9 is formed.

Also in the indexable end mill (indexable radius end mill) of the second embodiment, the first and second two cutting operations of the above-described second embodiment having the insert body 21 of the same shape and size The inserts 21A and 21B are detachably attached to the two insert mounting seats 32 formed on the tip of the end mill body 31 on opposite sides in the circumferential direction. However, the two insert mounting seats 32 in the indexable end mill and the end mill main body 31 of this second embodiment are 180° rotationally symmetrical with respect to the axis O of the end mill main body 31, except for the convex portion 33 projecting from the bottom surface 32a. is formed in

Of the two insert mounting seats 32, the bottom surface 32a of the first insert mounting seat 32A shown in FIG. A first projection 33A is formed, and, although not shown, a fourth projection is formed on the tip side of the end mill main body 31 to accommodate the first groove 8A of the first cutting insert 21A. . In the first insert mounting seat 32A, the first cutting insert 21A extends the arc-shaped cutting edge portion 22a of the first cutting edge 22A from the inner peripheral side of the front end of the end mill main body 31 to the outer peripheral side of the rear end. Thus, it is detachably attached by the clamp screw 15 .

At this time, the linear cutting edge portion 22b of the first cutting edge 22A is positioned on a cylindrical surface centered on the axis O, and the other linear cutting edge portion 22c is arranged on a plane perpendicular to the axis O. or arranged so as to extend slightly toward the rear end side toward the inner peripheral side of the end mill main body 31 . As shown in FIGS. 29 and 30, in the indexable end mill and the end mill body 31 of the second embodiment, the bottom surface 32a of the insert mounting seat 32 moves toward the rear end of the end mill body 31 in the end mill rotation direction T. , so that the first cutting edge 22A of the first cutting insert 21A mounted as described above and the second cutting edge 22A of the second cutting insert 21B, which will be described below, The cutting edge 22B of is provided with a positive axial rake angle.

Of the two insert mounting seats 32, the bottom surface 32a of the second insert mounting seat 32B shown in FIG. A second convex portion 33B is formed to contact, and a third convex portion 33C is formed on the rear end side of the end mill body 31 to contact the first groove portion 8A of the second cutting insert 21B. . In this second insert mounting seat 32B, the second cutting insert 21B is positioned such that the second cutting edge 22B, except for the nick 10, is the same as the first cutting edge of the first cutting insert 21A in the rotational trajectory about the axis O. 22A and is detachably attached.

Also in this second embodiment, although illustration is omitted, the length L1 in the extending direction of the first projection 33A of the first insert mounting seat 32A of the end mill main body 31 and the length L1 of the second insert mounting The length L2 in the direction in which the second convex portion 33B of the seat 32B extends is the length in the direction in which the first groove portion 8A in the insert body 21 of the first and second cutting inserts 21A and 21B extends. It is longer than N1.

Therefore, in the indexable end mill (indexable radius end mill) of the second embodiment, the insert bodies 21 of the first and second cutting inserts 21A and 21B are misplaced as in the first embodiment. It is possible to prevent incorrect mounting in the wrong direction. For this reason, the used cutting edge 22 is mistakenly used again for cutting, and the cutting edge 22 dulled by wear or the like causes an increase in cutting resistance or a decrease in cutting efficiency. There is no

In addition, since it is possible to avoid that the rotation trajectory of the nick 10 coincides with the first and second cutting edges 22A and 22B of the first and second cutting inserts 21A and 21B, the original cutting edge of the indexable end mill can be avoided. 22 (the first and second cutting edges 22A and 22B) can be ensured in accuracy of the diameter of the blade, and the overlap of the rotational trajectories of these nicks 10 leaves a ridge-like uncut portion on the machined surface of the work material. does not occur. Furthermore, since chips generated by the first and second cutting edges 22A and 22B can be divided by the nick 10 before they are elongated or widened, cutting resistance can be reliably reduced. can.

Furthermore, in the cutting insert and the indexable end mill (indexable radius end mill) of the second embodiment, the most recessed position M toward the seating surface 3 of the opening of the nick 10 to the flank surface 4 is the rake. As shown in FIG. 32 in a perspective view from the surface 2 side, the nick 10 is arranged at a position that does not overlap the opening of the groove 8 to the flank 4, and particularly the entire nick 10 extends to the flank 4 of the groove 8. Since it is arranged at a position that does not overlap with the opening of the cutting insert, the thickness between the nick 10 and the seating surface 3 and between the groove 8 and the rake surface 2 can be secured, and the insert body of the cutting insert Even if a large cutting load acts on 21, damage can be prevented.

Further, in the insert body 21 of the cutting insert of the second embodiment, another linear cutting edge portion 22c is formed in contact with the other end of the arcuate cutting edge portion 22a. In the type end mill, another linear cutting edge portion 22c is arranged on a plane perpendicular to the axis O, or is arranged so as to extend slightly toward the rear end side toward the inner peripheral side of the end mill body 31. As shown in FIG. Therefore, even if the feed of the end mill main body 31 is increased, the bottom surface of the machined surface of the work can be smoothly finished by allowing the other linear cutting edge portion 22c to act as a scrubbing edge or a wiper edge.

33 and 34 show modifications of the cutting insert and the indexable end mill of the second embodiment, which are common to the second embodiment shown in FIGS. 20 to 32. The same reference numerals are assigned to the parts that In this modification, in the second groove portion 8B of the two groove portions 8, the second wall surface 8b facing the second end portion 2b side of the rake surface 2 is provided with the second wall surface 8b of the rake surface 2. The difference from the second embodiment is that a concave portion 8d is formed on the side of the end portion 2a of the first embodiment.

The concave portion 8d is formed in a rectangular or trapezoidal shape extending in the direction in which the second groove portion 8B extends when viewed from the direction facing the seating surface 3. In this modification, the concave portion 8d extends in the direction in which the second groove portion 8B extends. A plurality of (two) are formed at intervals. In addition, in the insert body 21 of the cutting insert of this modified example, the rake face 2, the cutting edge 22, and the nick 10 are formed in the same manner as in the second embodiment.

In the cutting insert of such a modified example, the second wall surface 8b of the second groove portion 8B that abuts on the first convex portion 33A of the first insert mounting seat 32A in the first cutting insert 21A has such a shape. Since the recessed portion 8d is formed, the grinding tool can escape to the recessed portion 8d when forming the wall surface (second wall surface 8b) of the groove portion 8 (second groove portion 8B) with a grinding tool. becomes easier. Although there are two concave portions 8d in this modified example, the number may be one or three or more. Further, the shape of the recess 8d when viewed from the direction facing the seating surface 3 may be circular, semi-circular, semi-elliptic, etc., in addition to the rectangular or trapezoidal shape as described above.

1, 21 insert body 1A, 21A first cutting insert 1B, 21B second cutting insert 2 rake face 3 seating face 4 flank face 5 main cutting edge (one of the two cutting edges)
5a Arc-shaped cutting edge portion of the major cutting edge 5 5b Linear cutting edge portion of the major cutting edge 5 6 Minor cutting edge (the other of the two cutting edges)
6a Arc-shaped cutting edge portion of minor cutting edge 6 6b Linear cutting edge portion of minor cutting edge 6 7 Mounting hole 8 Groove portion 8A First groove portion 8B Second groove portion 9 Narrow portion 10 Nick 11, 31 End mill main body 12, 32 insert mounting seat 12A, 32A first insert mounting seat 12B, 32B second insert mounting seat 14A, 33A first convex portion 14B, 33B second convex portion 14C, 33C third convex portion 14D fourth Projection 22 Cutting edge 22A First cutting edge 22B Second cutting edge 33 Projection N1 Length in the direction in which the first groove 8A extends N2 Length in the direction in which the second groove 8B extends L1 th Length in the direction in which the first protrusions 14A and 33A extend L2 Length in the direction in which the second protrusions 14B and 33B extend E Center line of the mounting hole 7 d Side of the mounting hole 7 of the first groove 8A distance from the center line E of the mounting hole 7 between the wall surface (first wall surface 8a) of the second groove portion 8B and the wall surface (second wall surface 8b) of the second groove portion 8B on the side of the mounting hole 7 O End mill rotation direction

Claims (11)

A first insert body having the same shape and size and having at least two cutting edges in a first insert mounting seat and a second insert mounting seat formed at the tip of an end mill body rotated about an axis. An indexable end mill in which a cutting insert and a second cutting insert are detachably attached,
The insert body includes a seating surface in close contact with the bottom surfaces of the first insert mounting seat and the second insert mounting seat, a mounting hole opening in the center of the seating surface and penetrating the insert body, and a mounting hole. a first groove and a second groove extending parallel to each other on the seating surface with the opening of the hole therebetween;
The length in the direction in which the first groove extends is shorter than the length in the direction in which the second groove extends,
The bottom surfaces of the first insert mounting seat and the second insert mounting seat are provided with screw holes into which clamp screws inserted through the mounting holes are screwed,
The first insert mounting seat is accommodated in the second groove portion when the mounting hole in the insert body of the first cutting insert is overlapped with the screw hole and the seating surface is brought into close contact with the bottom surface. at least a first protrusion extending to
The second insert mounting seat is accommodated in the second groove portion when the mounting hole in the insert body of the second cutting insert is overlapped with the screw hole and the seating surface is brought into close contact with the bottom surface. at least a second protrusion extending to
The length in the direction in which the first protrusion extends and the length in the direction in which the second protrusion extends are longer than the length in the direction in which the first groove extends. Indexable end mill characterized by A wall surface of the first groove portion on the mounting hole side and a wall surface of the second groove portion on the mounting hole side extend parallel to each other in a bottom view viewed from a direction facing the seating surface, and 2. The indexable end mill according to claim 1, wherein the distances from the center line of the mounting holes are equal to each other. The second groove portion has a narrow portion in which the groove width becomes narrower from one end side to the other end side in the direction in which the second groove portion extends. 3. The indexable end mill according to item 2. At least one of the first convex portion and the second convex portion is located on the other end side of the extending direction of the second groove portion in the portion accommodated in the narrow portion of the second groove portion. 4. The indexable end mill according to claim 3, wherein the width becomes wider as it goes from the edge to the one end side. The second insert mounting seat is configured such that the mounting hole in the insert body of the second cutting insert having the second convex portion accommodated in the second groove portion overlaps with the screw hole so that the seating surface is the bottom surface. 5. The third convex portion extending so as to be accommodated in the first groove portion when brought into close contact with the body, according to any one of claims 1 to 4. indexable end mill. The first insert mounting seat is configured such that the mounting hole in the insert body of the first cutting insert having the first convex portion accommodated in the second groove portion overlaps the screw hole so that the seating surface is the bottom surface. 6. A fourth convex portion extending so as to be accommodated in the first groove portion when brought into close contact with the body, according to any one of claims 1 to 5. indexable end mill. The first groove portion is formed in a blind groove shape that opens only to one edge portion of the seating surface, and
7. The second groove is formed in the shape of a through groove that traverses the seating surface and opens to two edge portions of the seating surface. 1. The indexable end mill according to item 1. The insert body has a rake face facing away from the seating surface and directed in the direction of rotation of the end mill body, and a flank extending around the rake face and the seating surface,
An arc-shaped cutting edge portion extending in an arc shape in a plan view seen from the direction facing the rake surface is provided at the intersection ridgeline portion between the rake face and the flank face, and an arc-shaped cutting edge portion is provided so as to be in contact with one end of the arc-shaped cutting edge portion. The two cutting edges each having a linear cutting edge portion extending to the rake face are formed by alternately locating the arcuate cutting edge portion and the linear cutting edge portion in the circumferential direction of the rake face,
One of the two cutting edges is a major cutting edge and the other is a minor cutting edge,
The arc-shaped cutting edge portion of the major cutting edge is formed to have a longer circumferential length with a radius equal to that of the arc-shaped cutting edge portion of the minor cutting edge,
In the first cutting insert, the arc-shaped cutting edge portion of the main cutting edge has the center of the arc of the arc-shaped cutting edge portion on the axis in the rotational trajectory about the axis, and the tip of the end mill body is positioned on the axis. attached to the first insert mounting seat so as to form a hemispherical shape extending from the axis to the outer peripheral side of the rear end;
In the second cutting insert, the arc-shaped cutting edge portion of the minor cutting edge forms the rotational locus of the arc-shaped cutting edge portion of the major cutting edge of the first cutting insert in the rotational locus about the axis. 8. The second insert mounting seat is mounted on the second insert mounting seat so as to overlap with the hemisphere and extend from a position away from the axis at the tip of the end mill body toward the outer periphery of the rear end. 1. The indexable end mill according to item 1. The insert body has a rake face facing away from the seating surface and directed in the direction of rotation of the end mill body, and a flank extending around the rake face and the seating surface,
An arc-shaped cutting edge portion extending in an arc shape in a plan view seen from the direction facing the rake surface is provided at the intersection ridgeline portion between the rake face and the flank face, and an arc-shaped cutting edge portion is provided so as to be in contact with one end of the arc-shaped cutting edge portion. The first cutting edge and the second cutting edge respectively provided with a linear cutting edge portion extending to and another linear cutting edge portion extending so as to contact the other end are connected to the other linear cutting edge portion and The arcuate cutting edge portion and the linear cutting edge portion are positioned in order in the circumferential direction of the rake face, and
The rake face is formed with groove-shaped nicks that reach the first cutting edge and the second cutting edge and open to the flank face,
The first cutting edge and the second cutting edge have a basic shape 180° rotationally symmetrical about the center line of the mounting hole except for the nick,
The first cutting insert and the second cutting insert are arranged so that the first cutting edge of the first cutting insert and the second cutting edge of the second cutting insert are arranged in the rotational trajectory about the axis. are attached to the first insert mounting seat and the second insert mounting seat by overlapping the basic shapes of
8. Any one of claims 1 to 7, characterized in that the nicks reaching the first cutting edge and the second cutting edge are formed so as not to overlap in the locus of rotation about the axis. 1. The indexable end mill according to item 1. An end mill main body of the indexable end mill according to any one of claims 1 to 9,
The bottom surfaces of the first insert mounting seat and the second insert mounting seat are provided with screw holes into which clamp screws inserted through the mounting holes of the insert body are screwed, and
The first insert mounting seat is accommodated in the second groove portion when the mounting hole in the insert body of the first cutting insert is overlapped with the screw hole and the seating surface is brought into close contact with the bottom surface. at least a first protrusion extending to
The second insert mounting seat is accommodated in the second groove portion when the mounting hole in the insert body of the second cutting insert is overlapped with the screw hole and the seating surface is brought into close contact with the bottom surface. at least a second protrusion extending to
The length in the direction in which the first protrusion extends and the length in the direction in which the second protrusion extends are longer than the length in the direction in which the first groove extends. The end mill body of an indexable end mill characterized by Cutting having an insert body with at least two cutting edges attached to the first insert mounting seat and the second insert mounting seat of the indexable end mill according to any one of claims 1 to 9 an insert,
The insert body includes a seating surface in close contact with the bottom surfaces of the first insert mounting seat and the second insert mounting seat, a mounting hole opening in the center of the seating surface and penetrating the insert body, and a mounting hole. a first groove and a second groove extending parallel to each other on the seating surface with the opening of the hole therebetween;
The cutting insert, wherein the length in the direction in which the first groove extends is shorter than the length in the direction in which the second groove extends.

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