JP2757744B2 - Indexable drill bits and indexable inserts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away type drilling tool (hereinafter simply referred to as a drilling tool) provided with a cutting edge tip for forming a bottom blade at the tip of a tool body, and such a tool. The present invention relates to a throw-away insert (hereinafter, simply referred to as an insert) used for a drilling tool.

[0002]

2. Description of the Related Art As a drilling tool of this kind, for example, a tool disclosed in Japanese Patent Application Laid-Open No. 58-181506 is known. In this drilling tool, a pair of chip discharge grooves are formed on the outer periphery of a tip portion of a tool body that is rotated around an axis, and a chip mounting seat formed at a tip portion of the chip discharge groove has an inner peripheral surface. The side cutting edge tip and the outer peripheral side cutting edge tip are detachably mounted.
Each of these cutting edge chips is a chip having a substantially rhombic shape in plan view and the same shape and size, and a pair of cutting edges of the same length are provided on each side edge of the rhomboid surface serving as a rake face. Are formed so as to intersect at an obtuse angle, and a pair of cutting blades formed on one side edge are mounted on the tool main body so as to be located at the forefront of the tool main body and serve as a bottom blade.

[0003] The chip mounting seat is formed so as to be recessed one step from the wall surface of the chip discharge groove facing the tool rotation direction. The mounting seat bottom surface facing the tool rotation direction parallel to this wall surface and the mounting seat bottom surface. It is defined by a plurality of mounting seat wall surfaces that rise and continue to the chip discharge groove wall surface. And each cutting edge chip has a pair of cutting blades serving as a bottom blade, with such a chip mounting seat having a seating surface opposite to the rhomboid surface serving as the rake surface in close contact with the mounting seat bottom surface. A flank (side surface of the chip) connected to another side ridge other than one side ridge is brought into contact with the mounting seat wall surface, and is mounted with a clamp screw or the like. Thus, the bottom blades of these cutting edge tips are configured so that the cutting paths thereof partially overlap each other, that is, the cutting edge located on the outer peripheral side of the bottom edge of the inner peripheral cutting edge tip and the outer peripheral side cutting edge. The cutting edge positioned on the inner peripheral side of the bottom edge of the insert is disposed so as to intersect with each other on a rotation locus on a plane including the axis, and both cutting edges are advanced by rotating the tool body. The cutting edge, which is the bottom edge of the tip, cuts the work material to make a hole.

[0004]

In order to perform high-precision drilling in such a drilling tool, the contact area between the cutting edge tip and the tip mounting seat is increased to make the tool body of the cutting edge tip. It is necessary to increase the rigidity of the cutting edge so that the cutting edge does not rattle due to the load during the drilling. Therefore, with the above drilling tool,
Of the flank surfaces arranged around the rake face of each cutting edge chip, other flank surfaces other than the flank surface connected to the pair of cutting blades serving as the bottom blade and arranged toward the tip side of the tool body. Almost all contact the mounting seat wall of the chip mounting seat,
A larger portion of the flank of the cutting edge tip is in close contact with the tool body so that a contact area between them is ensured.

[0005] However, in the cutting edge tip of the drilling tool, each side edge is constituted by a pair of cutting edges bent at an equal length. Therefore, the flank face connected to such a cutting edge also has the cutting surface. They are formed to have the same length in the circumferential direction of the blade tip and to bend and intersect each other. Therefore, in the cutting edge tip having the bent flank in this way, in order to ensure sufficient contact between the flank and the mounting seat wall surface to ensure the contact area, it is necessary to adjust the tip in accordance with the molding accuracy of the cutting edge tip. The mounting seat must also be precisely molded with high precision. That is, the mounting seat wall surface must be strictly formed in accordance with the intersection angle and the length of each flank of the flank which bends and intersects each other. However, it is not easy to form all the mounting seat wall surfaces with such high precision, and a great deal of labor and time are required. Moreover, in the above-mentioned drilling tool, only the mounting accuracy of one of the mounting seat walls among the mounting seat walls to which the other flank abuts and comes into close contact is impaired, and all other mounting seat walls are cut off. There is a possibility that contact with the flank of the blade tip may not be obtained, or rattling may occur on the cutting tip. As a result, there is a problem that the rigidity and accuracy of attachment to the tool main body are significantly deteriorated, and the machining accuracy at the time of drilling is reduced.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a tool body rotated around an axis, wherein a pair of chip discharge grooves are formed on the outer periphery of a tip end thereof. Drilling in which an inner peripheral cutting edge tip forming the inner peripheral side of the bottom blade and an outer peripheral cutting edge tip forming the outer peripheral side of the bottom blade are detachably mounted on the formed chip mounting seat. In the tool, the inner peripheral side cutting edge tip and the outer peripheral side cutting edge tip are formed into a rhombic flat plate having the same shape and the same size, and a pair of ridges each forming an acute angle of the rhombic surface on each side ridge of the rhomboid surface. A pair of side ridge cutting edges are formed adjacent to the apex, respectively, and the apex forming the acute angle has an intersection angle symmetrical with respect to a bisector of the apex and larger than the apex angle of the apex. And a pair of nose cutting edges shorter than the above-mentioned edge cutting edge are each V-shaped. Formed, to form a nose radius edge at the intersection between the pair of the nose portion cutting edge with a,
At the intersection of the side edge cutting edge and the nose cutting edge adjacent to each other, a round edge between cutting edges is formed, while the tip mounting seat is on the side opposite to the rhombic surface of each cutting edge tip. A mounting seat bottom surface that can be in close contact with the seating surface to be disposed, and a side surface that rises from the mounting seat bottom surface and that is arranged around the rhombic surface of the cutting edge tip and that is connected to the side edge cutting edge. And a mounting seat wall surface that can be contacted.

[0007]

In the drilling tool having such a configuration, of the respective cutting edges formed on the cutting edge tip, the side edge cutting edge is formed to be longer than the nose portion cutting edge, while the tip mounting is performed. The mounting seat wall surface of the seat is formed so as to abut only on the flank surface portion of the flank surface (side surface) of the cutting blade tip, which is continuous with the side edge cutting blade, and other nose portion cutting blades and nose round blades. ,
In addition, the flank portion connected to the inter-cutting blade is not in contact with the mounting seat wall surface. That is, according to the drilling tool having the above-described configuration, the cutting edge tip is attached to the tip mounting seat by causing a relatively long flank surface portion connected to the side edge cutting edge to abut against the mounting seat wall surface. While the contact area with the seat can be kept large, the flank part that is relatively short and bends in a complicated way dare to avoid contact with the mounting seat wall, so that the mounting seat wall can be bent as much as possible. This makes it possible to easily form the chip mounting seat and improve the forming accuracy of each mounting seat wall surface.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In this embodiment, the tool main body 11 has a substantially cylindrical shaft shape, and a shank portion for mounting the tool main body 11 on a machine tool such as a machining center is provided on the base end side (right side in FIGS. 1 and 2). Is provided. Further, a flange portion 12 is formed on the tip side (left side in FIGS. 1 and 2) of the shank portion so as to be located substantially at the center of the tool main body 11 in the direction of the axis O. In this embodiment, the flange portion 12 has a truncated cone-shaped reduced diameter portion 12a whose diameter gradually decreases toward the tip end side of the tool body 11.
And a disk-shaped flange portion 12b connected to the base end thereof, and a surface facing the base end of the flange 12b is an annular surface 12c. Then, as shown in FIG. 1, in a state where the tool main body 11 is mounted on a cylindrical holding portion H such as a spindle end of the machine tool, the annular surface 12c is formed.
Is formed so as to substantially entirely contact the front end surface of the holding portion H. The outer diameter E of the annular surface 12c is appropriately set in accordance with the dimensions of the tool body 11, the machining conditions, and the like, but the outer diameter D of the bottom blade ranges from 1.1 × D to 3.0 × D. It is desirable to be set to.

On the other hand, on the outer periphery of the distal end portion of the tool main body 11, an opening is formed on the distal end surface 11a of the tool main body 11.
Two chip discharge grooves 13, 13 extending toward the base end side in parallel to the direction of the axis O are formed so as to be located on opposite sides in the circumferential direction of the tool body 11. In the present embodiment, each of these chip discharge grooves 13, 13 is provided in the rotational direction of the tool body 11 (counterclockwise arrow T in FIGS. 3 and 7).
Direction), a first wall portion 13a facing the side, and the first wall portion 13a
Second wall portion 13b that is substantially perpendicular to the surface and faces rearward in the tool rotation direction.
And an inner wall surface defined by the flange portion 1 and the distal end of the tool body 11 as shown in FIGS.
The second flange portion 12b extends to the front. A tip mounting seat 14 is formed at the tip of the first wall portion 13a of each of the chip discharge grooves 13 and 13 so as to be depressed one step from the first wall portion 13a. An inner peripheral side chip mounting seat 14A is located on the inner peripheral side, that is, on the axis O side, and an outer peripheral side chip mounting seat 14B is located on the outer peripheral side.

[0010] As shown in FIGS. 6 to 8, each of the chip discharge grooves 13, 1 is provided on the tip end surface 11 a of the tool body 11.
3 so as to extend along the edge on the rear side in the tool rotation direction of the tip side opening, ie, the tip end face 11a and the chip discharge groove 13
The recesses 15A, 15 recessed on the base end side of the tool body 11 so as to extend along the intersection ridge line portion with each second wall portion 13b.
B are formed respectively, and these recesses 15A, 1
The rear side in the tool rotation direction of 5B is a chip discharge groove 13,
13 and is made to communicate with the chip discharge groove 13. However, in this embodiment, in accordance with the arrangement of each cutting edge that is the bottom edge of the cutting edge tip described below,
Of the recesses 15A and 15B, a recess 15A formed rearward in the tool rotation direction of the inner peripheral side cutting edge tip mounting seat 14A is formed elongated on the edge side, and the tool of the outer peripheral side cutting edge tip mounting seat 14B is formed. Recess 15B formed rearward in rotation direction
Are formed wide except for the outer peripheral side of the tip end surface 11a.

On the other hand, in the tool body 11, one end is opened to the front end face 11a and the other end is opened to the base end face 11b of the shank portion of the tool body 11.
Oil holes 16, 16 are formed, and the tip end surface 11
a have openings 16a, 16a of these oil holes 16, 16;
Is formed. In the present embodiment, these openings 1
The recesses 15A, 1a are located near the edge of the chip discharge groove 13 on the rear side in the tool rotation direction.
5B is formed so as to open to the bottom surface, whereby each oil hole 16 communicates with the chip discharge groove 13 via the recesses 15A and 15B.

Further, in the present embodiment, the bottom surface of each of the recesses 15A and 15B of the front end surface 11a extends from the opening 16a of the oil hole 16 toward the rear side in the tool rotation direction.
Each of the grooves 17 is formed. This concave groove 17
In this embodiment, the cross section is formed in a U-shape that opens toward the tip end of the tool body 11, and the opening 16a of the oil hole 16 as shown in FIG.
The tool is formed so as to be inclined toward the inner peripheral side of the tool main body 11 from the rear toward the tool rotation direction. The groove 17 is formed such that the end on the tool rotation direction rear side is opened at the tip of the second wall portion 13 b of the chip discharge groove 13. This also allows the oil hole 16 and the chip discharge groove 13 to communicate with each other.

On the other hand, in the present embodiment, the cutting edge tip 18 attached to the tip attachment seats 14A and 14B is formed of a hard material such as a cemented carbide and has a rake face 19 as shown in FIGS. In addition, the positive chip is a flat positive chip having a substantially rhombic shape in plan view from the seating surface 20 side. Therefore, the rake face 19 and the seating face 20
A clearance angle is given to a side surface which is arranged around the flank and is a flank surface 21, and in this embodiment, the clearance angle α is set to 11 °. In the cutting edge tip 18, the rhomboid surface presented by the rake face 19 has a crossing angle β of two ridges intersecting at a pair of apexes C ₁ and C ₁ forming an acute angle in a range of 55 ° to 80 °. Is preferably set to 60 ° in this embodiment.

On the four side edges of the rake face 19, side edge cutting edges 22 are formed, respectively. The length A of the side edge cutting edge 22 is equal to the rake face 19.
Assuming that the diameter of a circle inscribed by the diamond formed by d is d, it is desirable to set the diameter to 50 to 110% of the diameter d, and in this embodiment, it is set to about 70% of the diameter d. Further, each of the pair of top C _1, C ₁ having the above-described acute angle, symmetrical with respect to said top C ₁ bisector H, and the two intersecting at large crossing angle γ than the crossing angle β The nose cutting edges 23, 23 are formed in a V-shape. Here, this intersection angle γ is 75 °
It is desirable to set the intersection angle β to be larger than the above-mentioned intersection angle β in a range of up to 120 °.
The length B of the nose cutting edge 23 (see FIG. 9) is shorter than the length A of the side ridge cutting edge 22. The ratio A: B to the length B of the blade 23 is set to be in the range of 2: 1 to 5: 1.

Furthermore, the intersection of these nose cutting edge 23, 23 in the top C _1, both nose cutting edge 2
A nose round blade 24 is formed so as to be smoothly connected to 3 and 23. The radius of curvature R ₁ of the nose round blade 24 is equal to 0.
It is desirable to set it to 2 to 1.2 mm, and in this embodiment, it is set to 0.4 mm. Further, at the intersection between the adjacent edge ridge cutting edge 22 and the nose cutting edge 23, a cutting edge round blade 25 is formed so as to be smoothly connected to both sides thereof. 25 has a radius of curvature R ₂ of 0.1.
０0.8 mm is desirable, and in this embodiment, it is set to 0.1 mm.
It is 6 mm. A breaker 26 protruding from the rake face 19 is formed inside the rake face 19 in a plan view. At the center of the cutting blade tip 18 in a plan view, a mounting hole 27 penetrating from the rake face 19 to the seating face 20 is formed.

In this embodiment, one of the cutting edges 18 having such a configuration is provided on the rake face 1 on the inner peripheral tip mounting seat 14A and one on the outer peripheral tip mounting seat 14B.
9 is oriented in the tool rotation direction, and one of the inter-cutting edge blades 25 is mounted so as to protrude toward the tip end in the direction of the axis O, and is fastened by the clamp screw 28 inserted into the mounting hole 27 and fixed to the tool body 11. ing. Here, FIGS. 12 and 13 show the respective chip mounting seats 14A and 14B in a state where the cutting blade tip 18 is not mounted, and FIG. 14 shows a cross section of the chip mounting seat 14 in a state where the cutting blade chip 18 is mounted. As shown in these figures, each of the chip mounting seats 14A and 14B has a mounting seat bottom surface 14a to which the seating surface 20 of the cutting blade tip 18 can be in close contact, and rises from the mounting seat bottom surface 14a. Are formed as spaces defined by the mounting seat wall surfaces 14b which can abut on the flank 21 of the cutting blade tip 18. In order to avoid interference with the tops C ₁ , C ₂ of the respective cutting edge tips 18, a recess 29 is provided at the intersection of the mounting seat wall surfaces 14 b adjacent to each other.
30 are formed.

The mounting seat wall surfaces 14b are formed so as to abut only on the flank portion 21a of the flank surface 21 which is continuous with the edge ridge cutting edge 22 when the respective cutting edge chips 18 are mounted. And the flank 21
Of the nose portion cutting edge 23 and the nose radius edge 24 and flank portion 21b continuous with the cutting edge between rounded edge 25 disposed around the top C ₁ at an acute angle of the cutting edge tip 18 into the recess 29 It is arranged so that contact with the mounting seat wall surface 14b is avoided. In addition, the cutting blade tip 18
Around the top C ₂ an obtuse angle have been arranged in the recess 30, are made also to avoid interference with the chip mounting seat 14 due to contact with the mounting seat wall 14b. Reference numeral 14c in the drawing denotes a screw hole into which the clamp screw 28 for fastening the cutting edge tip 18 is screwed.

[0018] Furthermore, in this embodiment, a pair of inner wall surfaces 29a in the recess 29 of the top C ₁ around is accommodated at an acute angle of the cutting edge tip 18, 29a, along with each erected to the mounting seat bottom 14a Mounting seat wall surfaces 14b, 14
b is formed so as to be recessed one step from the inner wall surface 29a of the chip mounting seat 14 so as to face inward.
It is formed as a space defined by 29a. These inner wall surfaces 29a, 29a are formed so as to intersect at an angle equal to the intersection angle γ between the adjacent nose cutting edges 23, via the nose round blade 24 of the cutting edge tip 18. When the cutting edge tip 18 is mounted on the tip mounting seat 14, the flank portions 21b, 21b of the flank face 21 on the side surface of the cutting edge tip 18 are continuous with the nose portion cutting edges 23, 23. Wall 29
a and 29a are arranged so as to be substantially parallel to each other. The inner wall surfaces 29a, 29a are smoothly connected to each other by an arcuate concave curved surface. In this embodiment, with the cutting blade tip 18 mounted, the first wall 1 of the chip discharge groove 13 as shown in FIG.
3a is set to be higher than the cutting edge 22 of the cutting edge tip 18 by a height t. Here, the height t between the two
Is preferably set so that the first wall portion 13a is higher than the cutting edge 22 within a range of 0.3 mm or less, and in this embodiment, the height t is set to 0.1 mm.

On the other hand, FIG. 15 shows a cutting tip 18 (hereinafter referred to as an inner cutting tip 18A) attached to the inner tip mounting seat 14A and an outer tip mounting seat 14B.
3 shows a rotation locus on a plane including the axis O with the cutting edge tip 18 (hereinafter, referred to as an outer peripheral side cutting edge tip 18B) attached to the cutting tool. However, in FIG. 15, each element of the inner cutting edge tip 18A is given a suffix A, and each element of the outer peripheral cutting tip 18B is given a suffix B.

As shown in FIG. 15, the inner peripheral side cutting edge tip 18A has an inner peripheral edge cutting edge 22A and an inner peripheral edge cutting edge 22A through an inter-cutting edge blade 25A. The nose portion cutting edge 23A located on the side is the bottom blade, and the inter-cutting edge blade 25A is located on the tip side in the direction of the axis O with respect to the side ridge portion cutting edge 22A and the nose portion cutting edge 23A adjacent to both ends (FIG. 15 (left side in FIG. 15). In the inner peripheral side cutting edge tip 18A, a nose radius blade 24A adjacent to the nose portion cutting edge 23A serving as a bottom edge is disposed so as to be over-centered beyond the axis O. The intersection angle θ ₁ between the virtual straight line L perpendicular to the axis O and passing through the tip of the inter-cutting edge blade 25A and the side edge cutting edge 22A is set to 6 ° in the present embodiment. .

The outer peripheral side cutting edge tip 18B has one ridge edge cutting edge 22B and a nose portion cutting edge 23B located on the outer peripheral side of the ridge edge cutting edge 22B via an inter-cutting edge blade 25B. Are the bottom blades, and the inter-cutting edge blade 25B is located protruding from the side ridge cutting edge 22B and the nose portion cutting edge 23B adjacent to both ends to the tip side in the axis O direction, and the inter-cutting edge radius is 25%. The tip of the blade 25B is disposed so as to coincide with the virtual straight line L. The outermost cutting edge tip 18B has a nose cutting edge 23B adjacent to the nose cutting edge 23B serving as a bottom blade via a nose round blade 24B. Right)
15, the nose portion cutting edge 23B is provided with a clearance angle ε. Here, the clearance angle ε of the nose cutting edge 23B
Is desirably 2 ° to 15 °, and in the present embodiment, 2 °
° is set.

Furthermore, the intersection angle θ formed by the virtual straight line L and the side edge cutting edge 22B of the outer peripheral side cutting edge tip 18B.
_2, the virtual straight line L and is set to be larger than the crossing angle theta ₁ formed by the Henryo portion cutting blade 22A of the inner peripheral cutting edge tip 18A, in this embodiment is set to 8 ° ing. Incidentally, the crossing angle theta ₁ is in a range of 1 ° ~ 19 °, and the crossing angle theta ₂ in the range of 2 ° to 20 °, that is set so as to satisfy θ ₁ <θ ₂ the relationship desirable . Then, under such an arrangement, the inner peripheral side cutting edge tip 18A and the outer peripheral side cutting edge tip 18B serve as the bottom blade of the inner peripheral side cutting edge tip 18A on the rotation locus on the plane including the axis O. The side ridge cutting blade 22A and the side ridge cutting blade 22B serving as the bottom blade of the outer peripheral side cutting blade tip 18B are disposed so as to intersect each other at the intersection Q.

On the other hand, in this embodiment, the inner wall surfaces of the chip discharge grooves 13, 13 are parallel to each other so as to extend substantially parallel to the axis O of the tool body 11, that is, to extend in the chip discharge direction. A plurality of rows of grooves 31 are formed.
Here, in the present embodiment, the grooves 31...
Are formed on both the first wall portion 13a and the second wall portion 13b, and are formed over substantially the entire area in the width direction of the wall portions 13a and 13b, that is, in the radial direction of the tool body 11. ing. In this embodiment, the groove 31 is
Regarding the direction of the axis O of the tool body 11, the first wall portion 13a
1 and 2, the groove 31 is formed so as to extend slightly from the base end side of the chip mounting seat 14 to just before the flange portion 12, while being formed in the second wall portion 13b. The groove 31 extends to the most proximal end side of the chip discharge groove 13 and extends to a position short of the flange portion 12 b of the flange portion 12. Further, in this embodiment, as shown in FIG. 5, the groove 31 has a semicircle that is depressed with respect to the walls 13 a, 13 b in a cross section orthogonal to the axis O of the tool body 11, and
It has a wavy shape in which semi-circles rising from 13b are alternately connected. Here, the cross-sectional shape of the groove 31 may be another shape such as a square or a triangle, but it is preferable that the bottom portion be a sufficiently curved shape.

In the drilling tool having such a configuration, the length A of the side ridge cutting edge 22 is longer than the length B of the nose cutting edge 23 among the cutting edges formed on the cutting edge tip 18. On the tip mounting seat 14 on which the cutting edge tip 18 is mounted, the flank face of the flank face (side face) 21 of the cutting edge tip 18 which is continuous with the edge ridge cutting edge 22 is formed. The mounting seat wall surfaces 14b contacting only the portion 21a are formed, and the other nose portion cutting blades 23,
The flank portion 21b connected to the nose radius blade 24 and the inter-cutting radius blade 25 is housed in the concave portion 29 and does not contact the mounting seat wall surface 24b. That is, the cutting edge tip 18 has a relatively long flank portion 21a attached to the mounting seat wall surface 14.
b, and is mounted on the chip mounting seat 14 so that a large contact area with the chip mounting seat 14 can be ensured.

Moreover, the above-mentioned drilling tool is relatively short,
By accommodating the complicatedly bent flank surface portion 21b in the concave portion 29 and intentionally avoiding contact with the mounting seat wall surface 14b, the bending of the mounting seat wall surfaces 14b can be suppressed as small as possible. For this reason, the tip mounting seat 14
It is possible to reduce the time and labor required for forming by facilitating the forming of the mounting hole 14b, and to improve the forming accuracy of each mounting seat wall surface 14b itself, that is, the forming accuracy of the chip mounting seat 14. As described above, it is possible to prevent the contact between the flank surface of the cutting edge tip and the mounting seat wall surface and the occurrence of rattling of the cutting edge tip. Therefore, according to the drilling tool having the above-described configuration, the improvement of the molding accuracy of the tip mounting seat 14 and the securing of the contact area between the cutting edge tip 18 and the tip mounting seat as described above are combined. Therefore, the rigidity and accuracy of the mounting of the cutting edge tip 18 to the tool body 11 can be improved, and it is possible to perform highly accurate drilling while preventing rattling of the cutting edge tip 18 and the like. In addition,
In this embodiment, the length A of the side edge cutting edge 22 of the cutting edge tip 18
And the ratio A: B of the length B of the nose portion cutting blade 25 to 2: 1
However, if the ratio A: B is too large, the nose portion cutting edge 25 becomes relatively too short and the cutting ability of the nose portion cutting edge 15 may be impaired. Conversely, if the ratio A: B is too small, the ratio of the length of the flank portion 21a to the flank portion 21b also becomes small, and the length of the flank portion 21a becomes relatively short. This is because the length of the mounting seat wall surface 14b may also be shortened, and a sufficient contact area between the two may not be secured.

In this embodiment, the periphery of the sharp edge C ₁ of the cutting edge tip 18 is disposed in the recess 29 formed in the tip mounting seat 14 in order to avoid interference with the top C _1. Thus, with the cutting edge tip 18 mounted on the tip mounting seat 14, the flank portions 21 b, 21 b connected to the nose cutting edges 23, 23 of the cutting edge tip 18, and the inner wall surfaces 29 a, 29 a of the concave portion 29. between the, so that the gap portion S extending in circumferential direction of the rake face 19 of the cutting insert 18 surrounds the sharp end C ₁ as shown in FIGS. 6 and 8 are formed. The mounting seat wall surface 29
a, 29a are formed so as to face inwardly of the tip mounting seat 14 so as to face the flank portions 21b, 21b and to intersect at an angle equal to the intersection angle γ of the nose cutting edges 24, 24. Therefore, the gap S is formed such that the width thereof is substantially constant in the circumferential direction. Therefore, by adopting such a configuration, in the present embodiment, it is possible to prevent the width of the gap S from becoming wide and narrow, so that chips and the like are stuck in the wide part, and chip clogging occurs. Can be prevented.

Further, in this embodiment, the first wall portion 13a of the chip discharge groove 13 is slightly higher than the respective cutting blades 22, 23 of the cutting chip 18 by the height t when the cutting blade tip 18 is mounted. In other words, the cutting blade 22 and the like do not protrude from the first wall portion 13a on the side of the mounting seat wall surface 14b of the chip mounting seat 14, for example. For this reason,
Chips move from the rake face 19 of the cutting edge tip 18 to the first wall portion 13.
When rubbing to a, it is possible to prevent such a situation that the cutting blade 22 is broken or the like, and it is also possible that the flank 21 of the cutting blade tip 18 protrudes from the first wall portion 13a. There is no flank 21 and first wall 13
It is also possible to prevent chips from being caught in the space a. If the height t from the cutting edge 22 to the first wall portion 13a is too large, chips may hit the stepped portion between the cutting edge 22 and chipping or wear may occur.
It is desirable to set it to 3 mm or less.

By the way, in a drilling tool in which the cutting edges 18A and 18B forming the bottom edge are deviated on the inner peripheral side and the outer peripheral side of the tool main body 11, both cutting edge tips 1A and 18B are used.
It is known that since the cutting forces acting on 8A and 18B are different, the force that the tool body 11 receives in the radial direction also deviates. On the other hand, in the drilling tool having the above-described configuration, the bottom edge of the outer peripheral side cutting edge tip 18B with respect to the imaginary straight line L orthogonal to the axis O in the rotation locus on the plane including the axis O as described above. The angle of intersection θ ₂ formed by the side ridge cutting edge 22B is set to the inner peripheral cutting edge tip 1 with respect to the virtual straight line L.
The intersection angle θ ₁ formed by the side edge cutting blade 22A serving as the bottom blade of 8A.
By arranging them so as to be larger than the above, such a factor can be eliminated.

That is, by adopting such a configuration, the side ridge cutting edge 22B of the outer cutting edge tip 18B is larger than the transverse cutting edge angle given to the side ridge cutting edge 22A of the inner peripheral cutting tip 18A. Inner cutting edge tip 18A in which only a small cutting force acts on the inner peripheral cutting edge tip 18A
In the side ridge cutting edge 22A, the fluctuation of the cutting force can be suppressed, but on the side ridge cutting edge 22B of the outer peripheral side cutting edge tip 18B where a large cutting force acts, the cutting force should be reduced. You can do it. Therefore, according to the drilling tool of the present embodiment, while reducing the cutting force acting on the entire bottom blade, the cutting force received by the inner cutting edge tip 18A and the cutting force received by the outer cutting edge tip 18B are reduced. This makes it possible to balance, thereby effectively canceling out the force acting in the radial direction of the tool body 11 at the time of drilling, and to reduce the force of the tool body 11 caused by such radial force imbalance. Swing and chatter can be suppressed. For this reason, even in the case of, for example, drilling a small diameter deep hole, especially in a so-called large L / D drilling in which runout and chattering are likely to occur, more stable drilling can be performed and excellent processing accuracy can be obtained. And a machined surface can be obtained.

In this embodiment, the intersection angle θ ₁ of the side edge cutting edge 22A of the inner peripheral cutting edge tip 18A with respect to the virtual straight line L is set to 6 °, and the outer peripheral cutting edge with respect to the virtual straight line L is set. Intersection angle θ of side edge cutting edge 22B of tip 18B
₂ is set to 8 °, but as described above, these intersection angles θ ₁ and θ ₂ are set so that the intersection angle θ ₁ is in the range of 1 ° to 19 ° and the intersection angle θ ₂ is 2 ° to 20 °. It is desirable to satisfy the relationship of θ ₁ <θ ₂ within the range. If the intersection angles θ ₁ and θ ₂ are too small, the side ridge cutting edges 22A and 22B serving as the bottom blades approach the virtual straight line L and the cutting force acting on the side ridge cutting edges 22A and 22B becomes a tool. The pushing force acting in the axial direction of the main body 11 becomes excessive. Conversely, if the crossing angles θ ₁ and θ ₂ are too large, the component force acting in the circumferential direction of the tool body 11 out of the cutting force acting on the side ridge cutting edges 22A and 22B becomes excessive, and the This results in an increase in the rotational driving force.

On the other hand, when drilling is performed by the drilling tool having the above-described configuration, the nose serving as the bottom blade is used for actual cutting among the cutting edges of the inner peripheral side cutting edge tip 18A. A cutting edge 23A, a cutting edge round blade 25A adjacent to the outer peripheral side of the nose cutting edge 23A, and a side ridge cutting edge 22A adjacent to the outer peripheral side of the cutting edge round blade 25A. This is a portion from the inter-round blade 25A to the intersection Q. The nose round blade 24A which is over-centered adjacent to the nose cutting edge 23A serving as the bottom blade is not used for cutting. In addition, the outer peripheral side cutting edge tip 1
Among the cutting edges of 8B, those that are actually used for cutting are a portion located on the outer peripheral side from the intersection Q among the side ridge cutting blades 22B serving as the bottom blade, and an outer peripheral side of the side ridge cutting blade 22B. Between the cutting edges adjacent to the cutting edge 25B,
B, a nose cutting edge 23B adjacent to the outer peripheral side, and a nose round blade 24 adjacent to the outer peripheral side of the nose cutting edge 23B.
B. In addition, the axis O of the nose round blade 24B
Since the clearance angle ε is given to the nose cutting edge 24B connected to the direction base end side as described above, it is not used for cutting.

Therefore, in the drilling tool having the above configuration, when one cutting edge tip 18 is used as the inner peripheral side cutting edge tip 18A, the cutting edge portion formed on the edge of the rake face 19 is cut. Is the range indicated by the symbol M in FIG. When the cutting edge tip 18 is used as the outer peripheral side cutting edge tip 18B, the range provided for the cutting is indicated by reference numeral N in FIG. Thus, as shown in FIG. 16, the cutting edge portion M used for cutting when one cutting edge tip 18 is used for cutting twice as the inner peripheral side cutting edge tip 18A, and the outer peripheral edge cutting edge tip 18B The cutting edge portion N used for cutting when used for cutting twice does not overlap. For this reason, according to the throw-away type drilling tool having the above-described configuration, one cutting edge tip 18 is used twice as the inner peripheral cutting edge tip 18 </ b> A, and the outer cutting edge tip 1 is used.
It is possible to carry out a total of four re-uses, two times as 8B. At this time, most of the cutting edge formed on the side edge of the rake face 19 of the cutting edge tip 18 is used up, so that it is possible to achieve almost maximum use as the cutting edge tip. Becomes

In this embodiment, the inner peripheral side cutting tip 18
A and the outer peripheral side cutting edge tip 18B are arranged such that the edge ridge edge cutting edges 22A and 22B, which are the respective bottom edges, in the rotation locus on a plane including the axis O, as shown in FIG. 2
They are arranged so as to intersect with each other at an intersection Q located in the middle of 2A and 22B. Therefore, even when one cutting edge tip 18 is used four times in total as described above, the cutting edge tip It is not possible to completely use up all the portions of the cutting edge formed on the edge of the rake face 19 of the rake face 18, and an unused portion is left on this edge in the range indicated by the symbol K in FIG. Therefore, in order to eliminate such an unused portion K, the position of the intersection Q is formed by the other pair of apex portions C ₂ , C ₂ forming an obtuse angle of the rhombus formed by the rake face 19.
The two cutting edge tips 18A, 18B may be arranged so as to match the above. By arranging in this manner, in FIG. 16, the cutting edge portion M used for cutting as the inner peripheral side cutting edge tip 18A and the cutting edge portion N used for cutting as the outer peripheral cutting edge tip 18B are each Since the tops C ₁ , C ₁ , C ₂ , and C ₂ are continuous, the unused portion K is eliminated and the rake face 1 is removed.
The cutting blades formed on the side edges of No. 9 can be used up evenly, and the use efficiency of the chip can be improved to the utmost.

Further, in the drilling tool according to the present embodiment, the flange 12 is formed on the tool body 11 as described above, and the tool body 11 holds the annular surface 12c of the flange 12 on the holding portion H of the machine tool. Is mounted on the holding portion H such that the entire surface thereof abuts on the tip end surface of the holding portion H. For this reason, it is possible to increase the contact area of the tool main body 11 with the holding portion H and improve the mounting rigidity thereof. As a result, the tool main body 11 can be firmly held by the holding portion H. In addition, it is possible to more reliably suppress runout and chatter of the tool body 11 during drilling. In addition, a truncated conical portion 12a having a truncated cone shape is formed on the distal end side of the flange portion 12, and the distal end portion of the tool body 11 that is provided with a cutting blade tip 18 serving as a bottom blade and receives a cutting force is formed by this reduced diameter portion. Since it is supported with high rigidity by the diameter portion 12a, runout and chatter are more reliably suppressed. Therefore, according to the present embodiment, as described above, the inner peripheral side cutting edge tip 18A
Than the crossing angle theta ₁ of Henryo portion cutting blade 22A, I effect coupled with by increasing the crossing angle theta ₂ of Henryo portion cutting blade 22B of the outer peripheral side cutting blade tip 18B, it size of L / D Also in drilling, it is possible to more effectively stabilize the processing and improve the processing accuracy and the quality of the processed surface.

In this embodiment, the outer diameter E of the annular surface 12c of the flange 12 is 1.1 × the outer diameter D of the bottom blade.
D to 3.0 × D.
Is smaller than 1.1 × D, the tool body 11 and the holding portion H
This is because the contact area between the tool body 11 and the tool body 11 may not be sufficiently increased, and the mounting rigidity of the tool body 11 may not be improved. Conversely, even if the outer diameter E is larger than 3.0 × D, the area of the tip end surface of the holding portion H is constant depending on the machine tool, so that the contact area cannot be further increased. However, there arises a disadvantage that the handleability of the device is impaired.

On the other hand, in machining with this kind of drilling tool, the work material is cut off by the edge cutting edges 22A and 22B and the nose cutting edges 23A and 23B serving as the bottom blade, and the chips F are continuously cut. This chip F is generated in the wall portions 13a,
13b, while passing through the chip discharge grooves 13, 13 while rubbing,
It is discharged from its proximal end. Also, during drilling, a suitable cutting fluid as a coolant is continuously supplied to the cutting portion through the oil hole 16, and after the cutting fluid is supplied to the cutting portion, the chip F flows through the chip discharge groove 13. At the same time, it flows toward the base end side in the axis O direction. As a result, the chips F are forcibly flushed to the base end side, and their discharge is promoted.

Here, in the present embodiment, the wall portions 13a and 13b of the chip discharge groove 13 are provided in the direction of the axis O of the tool body 11,
That is, a plurality of rows of grooves 3 extending along the chip F discharging direction
Are formed, thereby reducing the contact area between the walls 13a, 13b and the chips F rubbing the walls 13a, 13b, as shown in FIG. 17, and reducing the friction generated between them. be able to. Accordingly, since the discharge of the chips F can be effectively promoted by adopting such a configuration, in particular, the L for the processing of the small diameter deep hole as described above is used.
Even when drilling with difficult-to-cut materials such as stainless steel and mild steel, or when drilling with difficult-to-cut materials such as stainless steel and mild steel, the chips generated during drilling are extremely smooth without any clogging. It can be removed and a sufficient drilling depth can be obtained. As described above, according to the present embodiment, it is possible to provide a highly versatile drilling tool that can be used even under severe conditions.

The chip F and the wall 13 of the chip discharge groove 13
In order to sufficiently reduce the contact friction with a, 13b,
The grooves 31 are preferably formed in the wall portions 13a and 13b at least in the width direction, that is, over the entire area in the radial direction of the tool body 11. However, even if the groove 31 is partially formed in the wall portions 13a and 13b, the contact friction of the chip F can be sufficiently reduced as compared with a drilling tool having no such groove 31. . Therefore, in some cases, the grooves 31...
May be formed partially on the wall portions 13a and 13b in the radial direction of the width. In the present embodiment, the grooves 31 are formed from a portion close to the tip mounting seat 14 on the tip end side in the direction of the axis O of the tool body 11, but the grooves 31 of the second wall portion 13b, Alternatively, the tip surface 1 of the tool body 11 including the grooves 31 of the first wall portion 13a is also included.
It may be formed before reaching 1a. FIG. 18 shows a drilling tool in which the grooves 31 of the second wall portion 13b of the chip discharge groove 13 extend to the tip end surface 11a of the tool body 11.

Further, in the present embodiment, on the base end side in the direction of the axis O, the grooves 31 formed in the second wall portion 13b of the chip discharge groove 13 are formed so as to extend into the flange portion 12. The groove 31 formed in the first wall portion 13a is the flange portion 1.
It is formed only before the second. However, the grooves 31 may also be formed over the entire area of the chip discharge grooves 13 in the direction of the axis O of the tool body 11, that is, the grooves 31 of the first wall portion 13a are formed as shown in FIG. Collar 1
It may be formed so as to extend into the inside of the second chip discharge groove 13. By adopting such a configuration, it is possible to discharge the chips F more smoothly.

Further, in the drilling tool of this embodiment, in addition to the grooves 31, the tip surface 11 a of the tool body 11 is recessed along the edge of the opening of the chip discharge groove 13 on the rear side in the tool rotation direction. A location 15 is formed, and one end opening 16 a of the oil hole 16 opens into the recess 15, and communicates with the chip discharge groove 13 via the recess 15. Therefore, the cutting fluid supplied from the oil hole 16 passes through the recess 15 and spreads over the entire width of the chip discharge groove 13, and then passes through the chip discharge groove 13 toward the base end side of the tool body 11 in the axial direction. Since it flows, the cutting fluid flows uniformly throughout the chip discharge groove 13. For this reason, according to this embodiment, the chips F in the chip discharge groove 13 can be forcibly and efficiently sent to and discharged toward the base end in the axial direction without leaving any excess, thereby more surely causing chip clogging. Can be prevented. The cutting fluid sent to the chip discharge groove 13 also enters the grooves 31 formed in the walls 13a, 13b and flows toward the base end, so that the walls 13a, 13b It is possible to further reduce the contact friction with the chip F that rubs the chip, and the occurrence of chip clogging can be more reliably prevented in combination with the above effects.

In the drilling tool of the present embodiment, in addition to the recess 15, an oil hole 16 is formed on the tip end surface 11 a of the tool body 11.
A groove 17 is formed to directly communicate the opening 16a with the chip discharge groove 13, so that the cutting oil can be supplied to the chip discharge groove 13 more stably, and the supply thereof can be performed. The amount can be increased, and the chips F can be discharged more smoothly. Further, in the present embodiment, the concave groove 17 is directed toward the inner peripheral side of the tool main body 11 toward the rear side in the tool rotation direction as shown in FIG. The cutting oil is discharged to the portion. Therefore, according to the present embodiment, it is possible to intensively supply the cutting fluid to the cutting part by the bottom blade, and it is possible to obtain the advantage that the cooling of the part and the bottom blade can be performed very efficiently.

In this embodiment, the tool body 1
Although both the concave portion 15 and the concave groove 17 are formed in the front end surface 11a of the first device, a configuration in which only one of them is formed may be employed depending on the processing conditions and the like. In addition, regarding the recess 15, the tip surface 1 of the tool main body 11 is provided.
1a, the bottom surface of the recess 15 is located on the base end side of the tool body 11 when viewed from the direction along the edge of the opening of the chip discharge groove 13 on the rear side in the tool rotation direction (the direction shown in FIGS. 6 and 8). The concave portion 15 may be formed in a concave curved surface shape, and by adopting such a configuration, the capacity of the concave portion 15 is increased so that more cutting oil is supplied to more effectively discharge chips and the like. Can be performed.

Further, in the above embodiment, the reduced diameter portion 12a of the flange portion 12 of the tool body 11 is formed in a truncated cone shape, and the ratio of the reduced diameter is set to be constant. As shown in FIG.
The diameter reducing portion 12d is formed such that the ratio of the diameter reduction gradually increases toward the tip side in the axis O direction,
The reduced diameter portion 12d may have a convex curved shape or a hemispherical shape in a side view. By adopting such a configuration, the rigidity of the tool main body 11 is further improved, and the tip portion is supported with higher rigidity. Accordingly, runout and chatter are further reduced, and the precision of the finished surface and the like are further reduced. Can be improved.

Further, in the above embodiment, the chip discharging groove 1
3 is formed so as to extend substantially parallel to the direction of the axis O of the tool body 11, and a hole formed by a first wall portion 13a and a second wall portion 13b whose inner wall surfaces of the chip discharge groove 13 are orthogonal to each other. The opening tool has been described.
24, the chip discharge grooves 41 may be spirally formed around the axis O. However,
In this embodiment, the wall portion 41a of the chip discharge groove 41 is formed in a concave curved surface concave toward the radially inner peripheral side of the tool main body 11,
The groove 31 extending spirally around the axis O along the chip discharge groove 41 is formed in the wall portion 41a.
A plurality of rows are formed in the entire area in the width direction of one. Further, in this embodiment, one oil hole 16 is formed along the axis O from the base end side of the tool body 11, and this oil hole 16 is formed at the tip end side.
It branches into a book and is opened at the tip end surface 11a of the tool body 11, so that the above-described opening 16a is formed.
In FIGS. 21 to 24, the same reference numerals are assigned to other parts common to the embodiment shown in FIGS. 1 to 17, and the description is omitted. Further, in the above embodiments, the wall portions 13 of the chip discharge grooves 13 and 41 are all provided.
Although a plurality of rows of grooves 31 are formed in the drilling tools a, 13b, 41a, etc., such grooves 31 may not necessarily be formed depending on processing conditions and the like.

[0045]

As described above, according to the present invention, since the cutting edge tip is attached to the tip mounting seat by making the relatively long flank face connected to the edge cutting edge abut against the mounting seat wall surface. The contact area between the cutting edge tip and the tip mounting seat can be kept large, while the relatively short and complicatedly bent flank connected to the nose cutting edge avoids contact with the mounting seat wall surface. Accordingly, the bending of the mounting seat wall surface can be suppressed as small as possible, and the tip mounting seat can be easily formed, and the forming accuracy of each mounting seat wall surface can be improved. Therefore, it is possible to improve rigidity and mounting accuracy of the cutting edge tip to the tool main body, thereby enabling drilling with excellent processing accuracy.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a side view from the opposite side of FIG.

FIG. 3 is a front view of the embodiment shown in FIG. 1 as viewed from the distal end side.

FIG. 4 is a rear view of the proximal end face 11b of the embodiment shown in FIG.

FIG. 5 is a sectional view of the chip discharge grooves 13, 13 of the embodiment shown in FIG.

FIG. 6 is an enlarged side view of the tip of the embodiment shown in FIG. 1;

FIG. 7 is an enlarged view of a distal end surface 11a of the embodiment shown in FIG.

FIG. 8 is an enlarged side view from the opposite side of FIG. 6;

FIG. 9 shows a cutting edge tip 18 used in the embodiment shown in FIG.
FIG.

10 is a YY sectional view of the cutting edge tip 18 shown in FIG.

11 is a ZZ sectional view (part) of the cutting edge tip 18 shown in FIG. 9;

FIG. 12 is a diagram showing an inner peripheral side tip mounting seat 14A.

FIG. 13 is a view showing an outer peripheral side tip mounting seat 14B.

FIG. 14 is a sectional view of the tip mounting seat 14.

FIG. 15 is an inner peripheral cutting edge tip 18A of the embodiment shown in FIG. 1;
It is a figure showing a rotation locus in a plane containing axis O of an outer peripheral side cutting edge tip 18B.

FIG. 16 is a plan view showing a cutting blade portion used for cutting in the cutting blade tip 18 shown in FIG. 9;

FIG. 17 is a cross-sectional view showing a state where chips F rub inside the chip discharge groove 13 of the embodiment shown in FIG. 1;

FIG. 18 is a view showing a modification of the embodiment shown in FIG. 1;

FIG. 19 is a view showing another modification of the embodiment shown in FIG. 1;

FIG. 20 is a diagram showing another modification of the embodiment shown in FIG. 1;

FIG. 21 is a side view showing another embodiment of the present invention.

FIG. 22 is a front view of the embodiment shown in FIG. 21 as viewed from the distal end side.

FIG. 23 is a side view from the opposite side of FIG. 21.

FIG. 24 is a rear view of the proximal end face 11b of the embodiment shown in FIG. 21.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Tool main body 12 Flange 13 Chip discharge groove 14 Chip mounting seat 14a Mounting seat bottom surface 14b Mounting seat wall surface 15 Concave 16 Oil hole 17 Concave groove 18A Inner peripheral cutting edge tip 18B Outer peripheral cutting edge tip 22 Edge cutting edge 23 Nose cutting edge 24 Nose round blade 25 Round blade between cutting edges 29, 30 Recess 29a of chip mounting seat 14 Inner wall surface of recess 29 31 Groove O Axis of tool body A Axis of cutting edge tip 18 length B cutting insert 18 of the nose portion each cutting blade tip 18A perpendicular to the length L axis O of the cutting edge 23, the virtual line theta ₁ inner circumferential side switching through of the cutting edge between rounded edge 25, 25 of the 18B crossing angle formed by the Henryo portion cutting 22B and the virtual straight line L of the crossing angle theta ₂ outer peripheral side cutting blade tip 18B of the Henryo portion cutting 22A of the blade tip 18A formed between the virtual straight line L is

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshikazu Iwata Gifu Prefecture, Kochi-cho, Anpachi-gun, Gifu Prefecture 1528 Nakashinda, Yokoi, Mitsubishi Materials Corporation Gifu Works (72) Inventor Toru Narita, Kobe-cho, Anpachi-gun, Gifu Prefecture 1528 Nakashinda, Yokoi, Mitsubishi Materials Corporation Gifu Works (72) Inventor Yasuhiko Kawade Yokoi, Kobe-cho, Anpachi-gun, Gifu Prefecture 1528 Nakashinta, Yokoi, Mitsubishi Materials Corporation Gifu Works (72) Inventor Tetsuo Morishima 1528 Nakanishita, Yokoi, Kobe-cho, Yasuhachi-gun, Gifu Prefecture Mitsubishi Materials Corporation Gifu Works (72) Inventor Kazuo Takasaki 1528, Naka-Nitta, Yokoi, Kobe-cho, Yasuhachi-gun, Gifu Prefecture Mitsubishi Materials Corporation (72) Inventor Nobuaki Matsumoto No. 1528 Nakashinden, Yokoi, Kobe-cho, Anpachi-gun, Gifu Prefecture Ground Mitsubishi Materials Corporation Gifu Works (56) References JP-A-58-181506 (JP, A) JP-A-54-116795 (JP, A) JP-A-3-123611 (JP, U) JP-A 62-178010 (JP, U) Actually open 63-127813 (JP, U) Actually open 57-73010 (JP, U) Actually open 59-183711 (JP, U) Actually open U) Japanese Utility Model Hei 1-12703 (JP, U) Japanese Utility Model Application Showa 60-91302 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B23B 51/00 B23B 27/14 B23B 51 / 06

Claims (17)

(57) [Claims] 1. A pair of chip discharge grooves are formed on the outer periphery of a tip end of a tool body rotated about an axis, and a chip mounting seat formed at a tip of these chip discharge grooves is provided on an inner peripheral side of a bottom blade. An inner peripheral side cutting edge tip and an outer peripheral side cutting edge tip forming the outer peripheral side of the bottom blade are removably mounted in a throw-away type drilling tool. The outer peripheral side cutting edge chip has the same shape and the same size of a rhombic flat plate, and each ridge of the rhomboid surface to be a rake face, and a pair of ridge portions respectively adjacent to a pair of vertexes forming an acute angle of the rhomboid surface. A cutting edge is formed, and the acute-angled apex is formed symmetrically with respect to a bisector of the apex and at an intersection angle larger than the apex angle of the apex, and the edge-side edge cutting edge is formed. The pair of shorter nose cutting edges are V
A nose round blade is formed at the intersection of the pair of nose cutting blades, and a cutting edge is formed at the intersection of the adjacent edge ridge cutting blade and the nose cutting blade adjacent to each other. While a round blade is formed, the tip mounting seat has a mounting seat bottom surface that can be in close contact with a seating surface disposed on the opposite side to the rhombic surface of each cutting edge tip,
A mounting seat wall that rises from the mounting seat bottom surface and that can be in contact with a side surface connected to the side ridge cutting edge among side surfaces arranged around the rhombic surface of the cutting blade tip is provided. Characteristic indexable drilling tool. 2. The method according to claim 1, wherein a length ratio of the edge cutting edge to the nose cutting edge in each of the cutting edge tips is set in a range of 2: 1 to 5: 1. Item 1. A throw-away drilling tool according to Item 1. 3. A concave portion is formed in the tip mounting seat at an intersection of the mounting seat wall surface to avoid interference with the apex forming the acute angle of each cutting edge tip.
Of the side surfaces of the cutting edge tip, facing the inside of the tip mounting seat so as to face the side surface connected to the pair of nose cutting edges, and at an angle substantially equal to the intersection angle of the pair of nose cutting edges. The indexable drilling tool according to claim 1 or 2, wherein a pair of intersecting inner wall surfaces is formed. 4. The inner peripheral side cutting edge tip includes one of the side ridge cutting edges and one of the nose cutting edges located adjacent to and on the inner peripheral side of the side ridge cutting edges. The edge between the cutting edge of the intersection of the side edge cutting edge and the nose portion cutting edge is projected to the axial direction tip side, and adjacent to the nose portion cutting edge and the bottom edge The nose radius blade is disposed so as to be over-centered beyond the axis. On the other hand, the outer peripheral side cutting edge tip is adjacent to the one side edge portion cutting edge and the side edge portion cutting edge. The one nose part cutting edge located at the bottom edge is a bottom blade, and the cutting edge between the cutting edges at the intersection of the side ridge part cutting edge and the nose part cutting blade is projected to the axial direction tip side, The nose portion cutting edge adjacent to the nose portion cutting edge set as the bottom edge via a nose radius blade is positioned rearward in the axial direction of the tool body. Is arranged to face radially inwardly with respect to said axis toward the, the further the outer peripheral side cutting blade tip and the inner peripheral side cutting blade tip,
In the rotation trajectory on a plane including the axis, the side ridge cutting blades serving as bottom blades intersect with each other, and the inter-cutting edge blades projecting toward each other in the axial direction are provided along the axis. While being arranged on one vertical imaginary straight line, the intersection angle between the side ridge cutting edge of the outer peripheral side cutting tip and the virtual straight line is equal to the side ridge cutting edge of the inner peripheral side cutting tip. The indexable drilling tool according to any one of claims 1 to 3, wherein the indexing tool is disposed so as to be larger than the intersection angle with the virtual straight line. 5. An intersection angle between a side edge cutting edge of the outer peripheral side cutting edge tip and the virtual straight line is set in a range of 2 ° to 20 °, and a side edge of the inner peripheral side cutting edge tip is set. The indexable drilling tool according to claim 4, wherein the intersection angle between the partial cutting edge and the virtual straight line is set within a range of 1 ° to 19 °. 6. The tool body includes a reduced diameter portion that gradually reduces in diameter toward the distal end in the axial direction, and a disk-shaped flange portion having an annular surface facing the base end in the axial direction. 6. The method according to claim 1, further comprising a flange portion, wherein the annular surface is capable of contacting substantially the entire front end surface of the holding portion on the machine tool side for rotatably holding the tool body. The indexable drilling tool according to any of the above. 7. The throwaway according to claim 6, wherein the diameter-reduced portion of the flange portion is formed so that the ratio of the diameter-reduced portion gradually increases toward the front end side in the axial direction. Type drilling tool. 8. The throwaway according to claim 1, wherein a plurality of rows of grooves extending along the chip discharge groove are formed on an inner wall surface of the chip discharge groove. Type drilling tool. 9. The chip discharge groove according to claim 8, wherein the chip discharge groove and the groove formed on the inner wall surface of the chip discharge groove extend substantially parallel to the axial direction. Indexable drilling tool. 10. The throw-away type hole according to claim 8, wherein the groove is formed at least in the width direction of the chip discharge groove over the entire inner wall surface. Dawning tool. 11. An inner wall surface of the chip discharge groove includes a first wall portion facing the tool rotation direction side and a second wall portion crossing the first wall portion and facing the tool rotation direction rear side, The indexable drilling tool according to any one of claims 8 to 10, wherein the groove is formed in both the first wall portion and the second wall portion. 12. A tip end surface of the tool body is formed in the tool body so as to be close to an edge of an opening of the chip discharge groove on the tip end surface on the rear side in the tool rotation direction. The indexable drilling tool according to any one of claims 1 to 11, wherein one end of the cutting oil hole is opened. 13. A tip end surface of the tool main body extends along an edge of an opening of the chip discharge groove on the rear side in the tool rotation direction, and is recessed toward the base end in the axial direction to communicate with the chip discharge groove. 13. The indexable drilling tool according to claim 12, wherein a concave portion is formed, and one end of the cutting oil hole is opened in a bottom surface of the concave portion. 14. The indexable drilling tool according to claim 13, wherein a bottom surface of the recess is formed to have a concave curved shape when viewed from a direction along the edge. 15. A front end surface of the tool body is formed with a concave groove extending from one end of the cutting oil hole opened in the front end surface to a rear side in a tool rotation direction and communicating with the chip discharge groove. The indexable drilling tool according to any one of claims 12 to 14, wherein: 16. A plate-like positive indexable insert having a substantially rhombic shape in plan view from the rake face side,
A pair of edge ridges are formed on the edge of the diamond-shaped surface serving as the rake face adjacent to the apex forming the acute angle of the rhomboid surface, and two apex of the edge are formed on the apex forming the acute angle. A pair of nose cutting edges shorter than the side ridge cutting edges are formed symmetrically with respect to the equal line and at an intersection angle larger than the apex angle of the apex. Nose round blades are formed at the intersections of the nose part cutting blades, and a round edge between the cutting edges is formed at the intersection of the adjacent edge ridge cutting edge and the nose part cutting blade adjacent to each other. A throwaway tip characterized by: 17. The apparatus according to claim 16, wherein a length ratio of the edge cutting edge to the nose cutting edge is set in a range of 2: 1 to 5: 1. Throwaway tip.