JP3185518B2 - Indexable inserts and cutters - 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 tip and a throw-away type cutter, such as a face mill or an end mill, on which the tip is mounted. In addition, the work material can be cut at right angles (90 ° shoulder wall cutting).

[0002]

2. Description of the Related Art Conventionally, as a throw-away tip mounted on this kind of throw-away type cutter, for example, FIG.
As shown in FIGS. 2 and 23, a rectangular plate-like chip 2 attached to the outer peripheral side of a milling cutter 1 such as a face milling machine.
There is. As shown in FIG. 22, the throw-away tip 2 has an upper surface 4 opposed to a lower surface 3 forming a seating surface, and four circumferential side surfaces 5 define a plane inclined outward from the lower surface 3 toward the upper surface 4. No. The ridge lines at which the side surfaces 5 and the upper surface 4 intersect each other form a main cutting edge 6, and a sub-cutting edge 7 is formed near a corner 4a on the same ridge line of each main cutting edge 6. The upper surface 4 forms a rake face, the side face 5 forms a flank of the main cutting edge 6 and the sub cutting edge 7, and the main cutting edge flank and the sub cutting edge flank are flush with each other (side face 5). Have been.
A screw hole 8 is formed in the center of the upper surface 4 to penetrate the upper and lower surfaces to mount and fix the chip 2 to a cutter or the like.

[0003] When such a throw-away tip 2 is attached to the seat at the outer peripheral end of the front milling cutter 1, a positive axial rake angle is formed so as to form a positive angle α with respect to the rotation axis L of the cutter body. And position it. Moreover, the cutter is positioned with a negative radial rake angle so as to form a negative angle β with respect to the axis M in the radial direction of the cutter body. When the work material W is to be cut at right angles (90 ° shoulder wall cutting) with such a cutter 1, as shown in FIG.
With the main cutting edge 6 located on the outer peripheral side of the cutter, a cut is made so as to form a right-angled wall surface of the work material W, and the sub cutting edge 7 on the outer side of the ridge located on the tip end side has a positive axial rake angle and a negative radial rake angle. Since the cutting angle is provided, the square-shaped chip 2 can perform right-angle cutting.

[0004]

However, in the above-described indexable insert 2, the cutter is mounted so that the axial rake angle is positive and the radial rake angle is negative. Since the clearance angle of the blade 7 is on the same plane (side surface 5), the clearance angle of the main cutting blade 6 becomes excessively positive. As a result, the strength of the cutting edge is reduced to easily cause chipping, so that there is a disadvantage that the life of the tip is short.

In view of the above circumstances, the present invention provides a throw-away tip and a throw-away type cutter which can perform right-angled cutting, greatly improve the life of the tip, and have good seating stability. The purpose is to:

[0006]

The indexable insert according to the present invention has the shape of a polygonal plate, the ridge of the upper surface facing the seating surface forms a cutting edge, and the upper surface is a rake surface. In the throwaway tip whose side facing the upper surface is a flank, a sub-cutting edge is provided near one corner of the ridge portion between the two corners, and intersects this sub-cutting edge at an obtuse angle. A main cutting edge extending toward the other corner is provided, and on the side surface, a sub cutting edge flank surface that extends in a plane from the seating surface to cross the sub cutting edge and has a positive clearance angle is provided. A small-width main cutting edge first flank extending along the main cutting edge is provided at an upper portion of a side surface intersecting the main cutting edge, and the main cutting edge first flank is a flank of a sub-cutting flank. A clearance angle smaller than the angle is set, and the clearance of the main cutting edge Between the main cutting edge first flank and the minor cutting edge flank of the side surface regions forming a first main clearance angle is smaller cutting edge than the minor cutting edge flank relief angle is rather larger than the major cutting edge first flank (2) A flank is formed.

The relief angle of the first flank of the main cutting edge is set to be negative. Further, the main cutting blades provided on the two ridges sandwiching the corner on the upper surface are substantially perpendicular to each other.
An arc-shaped or chamfered corner blade is formed at a corner between the two ridges. A flat land is formed on the ridge portion of the upper surface, and a breaker groove is provided inside the land. The flat land is characterized in that the width of the sub-cutting edge and the corner portion following the sub-cutting edge are formed larger than the other portions. A notch is provided at a ridgeline at a boundary between the sub cutting edge and the main cutting edge. The cutout is characterized in that the cutout is formed by cutting out the upper surface and the side surface in an arc shape or a polygonal shape.

The indexable cutter according to the present invention comprises:
A throwaway tip that has a polygonal plate shape, the ridge of the upper surface facing the seating surface forms a cutting edge, the upper surface is a rake surface, and the side surface from the seating surface to the upper surface is a flank, With the axial rake angle set to a positive angle and the radial rake angle set to a negative angle, in a throw-away type cutter mounted on the cutter body, the throw-away tip is any of the above-described throw-away tips, and the cutter body In the front view, the first flank of the main cutting edge is disposed at a position above the center, and the front end and the rear end of the main cutting edge located on the outer peripheral side have the same radius of rotation about the rotation axis of the cutter body. It is characterized by having. In addition, the sub cutting edge flank of the throw-away tip and the main cutting edge second flank of the adjacent side abut on two intersecting side receiving portions of the tip mounting portion formed on the outer peripheral side of the tip of the cutter. It is characterized by having been done. The sub cutting edge flank of the throw-away tip is in contact with the radial receiving side receiving portion of the tip mounting portion, and the main cutting edge second flank is in contact with the axial receiving side receiving portion. It is characterized by.

[0009]

When the indexable insert according to the present invention is mounted on a cutter such that the radial rake angle becomes negative and the axial rake angle becomes positive,
In the part of the outer peripheral cutting edge, the flank of the auxiliary cutting edge located at the base end side of the tool is located on the side close to the rotation axis of the cutting tool, but has a positive clearance angle, so that the surface of the workpiece Since the first flank of the main cutting edge of the main cutting edge is relatively far from the rotation axis of the cutting tool, the flank angle can be made smaller and the cutting edge strength is high. Also, since the clearance angle of the first flank of the main cutting edge is negative,
Particularly, the cutting edge strength of the main cutting edge portion is high. Since the width of the flat land is increased in the sub cutting edge and the corner portion following the sub cutting edge, the cutting edge strength in this portion is higher. By providing a notch between the sub cutting edge and the main cutting edge, it is possible to prevent the width of the sub cutting edge from increasing even if the sub cutting edge wears out during cutting, thereby increasing the surface pressure and generating chatter vibration. And reduce the wear of the main cutting edge.

In the indexable cutter according to the present invention, right angle cutting can be performed, and the first flank of the main cutting edge is relatively far from the rotation axis of the cutting tool at the outer peripheral cutting edge. The clearance angle of the flank of the minor cutting edge can be made smaller, the strength of the cutting edge is high, and chipping hardly occurs. Also, the sub cutting edge flank on one side of the throw-away tip and the main cutting edge second flank on the side adjacent thereto are fixed by contacting the two side receiving portions of the tip mounting portion of the cutter body. Therefore, the cutter body receives different positions of the two chip side surfaces, and the outer peripheral side and the tip side of the chip side surfaces are supported, so that the seating is stable and stable cutting is possible.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 8 show a first embodiment of the present invention. FIG. 1 is a plan view of a throw-away tip mounted on a front milling cutter according to the present embodiment, FIG. 2 is a side view, and FIG. FIG. 4 is a partial cross-sectional view taken along the line XX of FIG.
5 is an enlarged view of a part, FIG. 5 is a partially cutaway side view showing a state where the throw-away tip is attached to the cutter, FIG. 6 is a partially enlarged view of FIG.
FIG. 7 is a side view of the cutter viewed from a different angle from FIG.
Is a front view of the cutter. 1 to 4, the throw-away tip 10 mounted on the front milling cutter according to the present embodiment has a square (substantially square in the figure) plate shape, and has an upper surface 12 facing a lower surface 11 forming a seating surface. Have. The main cutting edge 1 is located on the ridge line of the upper surface 12 which forms approximately four sides.
3 are formed, and an arc-shaped corner blade 14 is provided at each corner. The main cutting edges 13 of adjacent ridges are orthogonal to each other (see FIG. 4). A small angle γ (for example, 1 to 5) with respect to the main cutting edge 13 is provided between the main cutting edge 13 and one corner edge 14 at each ridge portion.
An auxiliary cutting edge 15 inclined inward on the upper surface 12 is formed only on the upper surface 12, and the sub cutting edge 15 is smoothly connected to the corner blade 14. The upper surface 12 forms a rake face, and a screw hole 16 for fixing a chip screw which penetrates to the lower surface 11 is formed in the center of the upper surface 12.

Each side surface 1 between the lower surface 11 and the upper surface 12
As shown in FIGS. 2 and 3, reference numeral 8 extends outward from the lower surface 11 toward the upper surface 12 so as to be inclined.
The plane region from 1 to the sub cutting edge 15 forms a sub cutting edge flank 19 having a positive clearance angle. Also, side 18
The small-width portion that intersects with the main cutting edge 13 and extends along the main cutting edge 13 to one corner is the main cutting edge first flank 20 of the main cutting edge 13 and is negative. It has a clearance angle. The first flank 20 of the main cutting edge is flat, and its width in the chip thickness direction extends to a predetermined length in parallel with the main cutting edge 13, and at the boundary portion near the sub cutting edge 15, the sub cutting edge It is diagonally cut up toward the boundary point P between 15 and the main cutting edge 13. In the side surface 18, the main flank first flank 2
In the area on the lower surface 11 side of 0, the sub cutting edge flank 19 is cut out in a triangular planar shape, and the main cutting edge second flank 22 is formed. The clearance angle of this main cutting edge second flank 22 is
The positive clearance angle is larger than the clearance angle of the first flank 20 of the main cutting edge and smaller than the clearance surface 19 of the sub cutting edge. However, the clearance angle of the main cutting edge second flank 22 is larger than the clearance angle of the main cutting edge first flank 20,
Alternatively, at least one of the smaller than the minor cutting edge flank 19 may be satisfied. In addition, the corner part of each side 18
A curved surface 14 a having a cylindrical side surface is formed which is inclined outward from the lower surface 11 toward the corner blade 14.

FIGS. 5 to 8 show a state in which such a throw-away tip 10 is mounted on the front milling cutter 24. FIG. This chip 10 is shown in the mounted state in FIG.
As shown in FIG. 6, the sub cutting edge 15 is located outside the front end face, and the main cutting edge 13 of the ridge portion adjacent to the outer peripheral front end has a front end and a rear end whose turning radius is about the rotation axis L. Are located so as to have the same dimensions. In FIG. 6, the tip mounting seat 2 formed on the outer peripheral side of the distal end of the cutter body 24a.
5 is a seat 26 on which the lower surface 11 of the chip 10 is seated;
6, an axial side receiving portion 27 facing the tip direction (axial direction), a radial side receiving portion 28 crossing the axial side receiving portion 27 and facing in the outer peripheral direction (radial direction), It is formed in a concave shape having a sunk portion 26 a located between the portions 27 and 28. Moreover, with the throw-away tip 10 mounted on the tip mounting seat 25,
The axial side surface receiving portion 27 has a throw-away tip 1
The main cutting edge second flank 22 of the main cutting edge abuts, and the sub-cutting flank 19 of the adjacent side surface abuts on the radial side surface receiving portion, whereby the tip 10 is positioned. I have.

The throw-away tip 10 is mounted on the cutter body 24a so that the axial rake angle is positive as shown in FIG. 7 and the radial rake angle is negative as shown in FIG. . Further, the first flank 20 of the main cutting edge is located at a position forward (upward in the center) in the rotational direction with respect to the axis M in the radial direction when viewed from the front as shown in FIG. In the chip 10 having the axial rake angle shown in FIG.
With respect to the above, the main cutting edge 13 serving as the outer peripheral edge is located on the distal side in the axial direction to form the right-angled wall surface of the workpiece W, and the sub cutting edge 15 not involved in cutting is located on the proximal end side. Moreover, since the auxiliary cutting edge flank 19, which is the flank on the base end side, is closer to the axis L than the main cutting edge first flank 20, the flank angle (negative) of the main cutting edge first flank 20 is larger. Is given to the minor cutting edge flank 19, and the minor cutting flank 19
Has a positive clearance angle. However, in the region of the main cutting edge 13, the clearance angle of the first flank 20 of the main cutting edge may be smaller than the flank angle of the flank 19 of the sub-cutting edge, since the clearance angle is relatively far from the axis L. Is set to For this reason, the edge strength of the main cutting edge 13 can be increased. In particular, the main cutting edge 13 has a longer length than the sub cutting edge 15 and is formed by cutting to form a right-angled wall surface. Since the contact area with the material W is large, the life of such a throw-away tip 10 can be significantly improved. The angle of the first flank 20 of the main cutting edge can be set arbitrarily within a range that does not come into contact with the right-angled wall surface of the workpiece W during cutting rotation.

In the throw-away cutter according to the present embodiment, the tip 1 is mounted on the cutter body 24a of the milling cutter 24 with the throw-away tip 10 attached.
0 indicates that the lower surface 11 is placed on the seat 26 of the chip mounting seat 25,
The main cutting edge second flank 22 of the side surface 18 facing the base end abuts against the axial side surface receiving portion 27, and the sub cutting edge flank 19 of the side surface 18 facing the center side of the cutter body 24a is a radial side receiving portion. Positioning is performed by contacting with the reference numeral 28. Then, the chip 10 is fixed to the cutter body 24a with screws or the like. Therefore, when the work material W is cut at right angles by such a throw-away type cutter 24, the outer peripheral portions of two adjacent side surfaces of the throw-away chip 10 are received by the two side receiving portions 27 and 28 of the chip mounting seat 25. The tip and the tip end portion are supported, so that the stability of the seating of the chip, especially during cutting, is good.

As described above, according to this embodiment, the clearance angle of the first flank 20 of the main cutting edge extending along the main cutting edge 13 of the indexable insert 10 is set to be negative. Without affecting the right-angled cutting performance, the edge strength of the main cutting edge can be increased, and the life of the insert can be greatly improved. Moreover, of the two adjacent side surfaces 18 of the throw-away tip 10,
On the one hand, the main cutting edge second flank 22 located on the outer peripheral side is supported by the axial side face receiving portion 27 of the cutter body 24a, and on the other hand, the secondary cutting edge flank 19 on the distal end side is supported by the radial side receiving portion 2.
8, the seating stability during cutting is good. still,
In the above description, the flank angle of the first flank 20 of the main cutting edge is set to be negative. However, the flank angle of the flank 19 of the sub cutting edge and the flank angle of the second flank 22 of the main cutting edge are not limited thereto. May be set to a small positive relief angle.

Next, a second embodiment of the present invention will be described with reference to FIGS.
2 will be described. FIG. 9 is a plan view of a throw-away tip mounted on a cutter according to the second embodiment, and FIG.
11 is a sectional view taken along line YY, FIG. 11 is an enlarged view of a portion B in FIG. 9, and FIG.
FIG. 11 is an enlarged view of a portion C in FIG. 10. In the present embodiment, flat lands 30 are provided over the entire circumference on ridges forming cutting edges on the upper surface 12. And, in the central region of the upper surface 12,
A bottom surface 31 which is parallel to the lower surface 11 and has a smaller distance from the cutting edge to the lower surface 11 is provided, and a flat inclined surface 3 extending from the land 30 to the bottom surface 31 is provided between the bottom surface 31 and the land 30.
2, the breaker groove 33 is formed. Therefore, according to the present embodiment, by providing the breaker groove 33 and the land 30, the discharge of chips becomes better, and the main cutting edge 13, the sub cutting edge 15, and the corner cutting edge 14 are provided.
Is enhanced, and the edge strength and insert life are improved.

FIGS. 13 to 16 show a third embodiment of the present invention. FIG. 13 is a plan view of a throw-away tip according to this embodiment, FIG. 14 is a side view, and FIG. FIG. 16 is an enlarged view of the portion shown in FIG. In the indexable insert 35 shown in FIGS. 13 to 15, at the ridge near the corner of the upper surface 12 of the indexable insert 35, one end of the sub cutting edge 15 is connected to the corner edge 14 at the boundary point P1, The other end ends at a boundary point P. A notch 36 is formed between the boundary point P and the following main cutting edge 13. The notch 36 is formed such that the inclination thereof is gentler on the side of the sub-cutting edge 15 than on the side of the main cutting edge 13 in a plan view (see FIG. 15). And is cut off (may be interrupted on the way without reaching the lower surface 11).
The width of the notch 36 in the ridge line direction may be set to an appropriate length, but is preferably set to be equal to or smaller than the sub-cutting edge 15.

In a conventional milling cutter equipped with a conventional throw-away insert, a right angle cutting is performed by a sub-cutting edge at the time of cutting, and when the sub-cutting edge is worn, the main cutting edge connected thereto is worn. The width of the sub-cutting edge increases in the direction of the cutting edge, and the surface pressure during cutting increases by that much, causing chatter vibration and wear of the main cutting edge, shortening the chip life. There were drawbacks.
In this regard, in the third embodiment, by adopting the above-described configuration, as shown in FIG. 16, as shown in FIG. Even if the cutting is performed by the sub-cutting edge 15 abutting on the material W and the sub-cutting edge 15 is worn, since the notch 36 is present between the sub-cutting edge 15 and the main cutting edge 13, the width of the sub-cutting edge 15 is reduced. Spread can be suppressed. Therefore, it is possible to suppress an increase in surface pressure even when the sub-cutting edge 15 is worn during cutting, to suppress occurrence of chatter vibration and wear of the main cutting edge, and also in this respect, to contribute to improvement of the chip life. .

FIG. 17 and FIG. 18 show a fourth embodiment of the present invention. In the present embodiment, as in the second embodiment, the flat land 3
0 is formed. Boundary point P of sub cutting edge 15 and main cutting edge 1
At the boundary with 3, the notch 37 is formed by cutting the land 25 toward the center of the upper surface, and the notch 37 is formed by cutting the side surface 18 from the upper surface 12 to the lower surface 11. In the present embodiment, the notch 37 is formed by notching to a depth smaller than the width of the land 30 in the direction of the center of the upper surface. Therefore, the cutting blade at the notch 37 is also reinforced by the land 30.

FIGS. 19 and 20 show a modification of the notch 36 according to the third embodiment. The notch 38 shown in FIG.
Has a trapezoidal cutout in horizontal section. The cutout 39 shown in FIG. 20 is formed by cutting out in an arc shape in a horizontal section. It should be noted that the shape of the notch is not limited to these, and other appropriate polygons and curved shapes can be adopted. FIG. 21 shows a fifth embodiment of the indexable insert according to the present invention. In this embodiment, the flat land 30 is wider in the area of the sub cutting edge 15 and the corner edge 14 than in other areas. The wide land portion 30a is provided. Thereby, there is an advantage that the cutting edge strength in the region of the sub cutting edge 15 and the corner blade 14 used particularly for cutting is further increased.

The notch 3 shown in FIGS.
Needless to say, the notches 8, 39 and other notches may be provided in the throw-away chip having the flat lands 30 shown in the fourth and fifth embodiments. Further, in each of the above-described embodiments, the corner blade 14 is formed in an arc shape in plan view, but may be formed in a chamfer.

[0023]

The indexable insert according to the present invention has the following features.
A minor cutting edge is provided near one corner of the ridge between the two corners, and a main cutting edge is provided at an obtuse angle to the minor cutting edge, and a side surface is provided from the seating surface to the minor cutting edge. An auxiliary cutting edge flank extending and having a positive clearance angle is provided, and a main cutting edge having a clearance angle smaller than a clearance angle of the auxiliary cutting surface flank at an upper portion of a side surface intersecting the main cutting edge. 1
A flank is provided, and a first main cutting edge at a flank of the main cutting edge is provided.
Between the flank and the minor cutting edge flank, because the clearance angle is smaller than the main cutting edge first flank relief angle is large rather minor cutting edge flank from the main cutting edge second flank is formed, In addition to being able to perform right-angled cutting, the edge strength of the main cutting edge can be particularly increased, and the life of the insert can be greatly improved.
In addition, since the clearance angle of the first flank of the main cutting edge of the throw-away insert is set to a negative value, the edge strength of the throw-away insert for right-angle cutting can be further increased, and the insert life is greatly improved. I do. Further, since the breaker groove is provided inside the ridge portion on the upper surface of the throw-away tip, the chip discharge performance is further improved. In addition, since the notch is provided at the boundary between the sub cutting edge and the main cutting edge of the indexable insert, it is possible to suppress an increase in the width of the sub cutting edge even if the sub cutting edge for cutting is worn out during cutting. As a result, it is possible to suppress an increase in the surface pressure and to suppress occurrence of chatter vibration and wear of the main cutting edge. This also contributes to the improvement of the chip life. Further, in the throw-away type cutter according to the present invention, the throw-away tip is the throw-away tip according to any one of claims 1 to 9, and the first flank of the main cutting edge is the center in a front view of the cutter body. The main cutting edge, which is located at the rising position and located on the outer peripheral side, has the same radius of rotation around the rotation axis of the cutter body at the front end and the rear end, so that it can be cut at right angles and especially the main cutting edge. The strength of the cutting edge of the blade portion can be increased, and the life of the tip can be greatly improved. In addition, the sub cutting edge flank of the throw-away tip and the main cutting edge second flank of the adjacent side abut on two intersecting side receiving portions of the tip mounting portion formed on the outer peripheral side of the tip of the cutter. Has been
Good sitting stability of indexable inserts during cutting.

[Brief description of the drawings]

FIG. 1 is a plan view of a throw-away tip according to a first embodiment of the present invention.

FIG. 2 is a side view of the throw-away tip shown in FIG.

FIG. 3 is a partial sectional view taken along line XX of FIG. 2;

FIG. 4 is an enlarged view of a portion A in FIG. 1;

FIG. 5 is a partially broken side view of the front milling cutter according to the first embodiment.

FIG. 6 is an enlarged view of the throw-away tip portion of FIG.

FIG. 7 is a side view of the cutter as viewed from a different angle from FIG. 5;

FIG. 8 is a front view of the cutter shown in FIG. 7;

FIG. 9 is a plan view of a throw-away tip according to a second embodiment of the present invention.

FIG. 10 is a sectional view taken along line YY of FIG. 9;

FIG. 11 is an enlarged view of a portion B in FIG. 9;

FIG. 12 is an enlarged view of a portion C in FIG. 10;

FIG. 13 is a plan view of a throw-away tip according to a third embodiment of the present invention.

FIG. 14 is a side view of the throw away tip shown in FIG.

FIG. 15 is an enlarged view of a portion D in FIG. 13;

FIG. 16 is a partially enlarged view showing a work material cutting state by a sub cutting edge of the indexable insert.

FIG. 17 is a plan view of a throw-away tip according to a fourth embodiment of the present invention.

FIG. 18 is an enlarged view of a portion E in FIG. 17;

FIG. 19 is a view similar to FIG. 15, showing a modified example of the cutout.

FIG. 20 is a view similar to FIG. 15, showing another modification of the cutout.

FIG. 21 is a plan view of a main part of a throw-away tip according to a fifth embodiment of the present invention.

FIG. 22 is a perspective view of a conventional throw-away tip.

FIG. 23 is a cross-sectional view showing a right-angled cutting state by a cutter to which a conventional throw-away tip is mounted.

[Explanation of symbols]

10, 35: indexable insert, 11: lower surface, 12
... top surface, 13 ... main cutting edge, 14 ... sub cutting edge, 18 ... side surface, 1
9: Sub-cutting flank, 20: Main cutting edge first flank, 22: Main cutting edge second flank, 24: Milling cutter, 25: Tip mounting seat, 27: Axial receiving surface, 28: Radial direction Receiving surface,
30: flat land, 30a: wide land portion, 33: breaker groove, 36, 37, 38, 39: notch.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroaki Hayashizaki 1511 Furamagi, Ishishita-cho, Yuki-gun, Ibaraki Pref. Mitsubishi Materials Corporation Tsukuba Works (56) References JP-A-4-294917 (JP, A) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) B23C 5/06-5/20

Claims (11)

(57) [Claims] 1. A polygonal plate-like shape, wherein a ridge line on an upper surface facing a seating surface forms a cutting edge, the upper surface is a rake surface, and a side surface from the seating surface to the upper surface is a flank surface. In the indexable insert, a sub-cutting edge is provided near one corner of the ridge line portion between two corners, and a main cutting edge which crosses at an obtuse angle to the sub-cutting edge and extends toward the other corner is provided. The side surface is provided with a sub cutting edge flank extending from the seating surface to cross the sub cutting edge and having a positive clearance angle, and the side surface intersecting the main cutting edge. The main flank is provided with a first flank having a small width extending along the main cutting edge at an upper portion of the main flank. And a front surface in a side surface region forming a flank surface of the main cutting edge. Between the main cutting edge first flank and the minor cutting edge flank, the main cutting edge second flank relief angle is smaller than the minor cutting edge flank relief angle is rather larger than the major cutting edge first flank formation A throwaway tip characterized by being made. 2. The indexable insert according to claim 1, wherein the clearance angle of the first flank of the main cutting edge is set to be negative. Wherein said main cutting edges respectively provided on two of the ridge portion sandwiching a corner in the upper surface, according to claim 1 or 2, characterized in that are substantially perpendicular to each other
The throw-away tip described in. 4. A cutting insert according to any one of claims 1 to 3, characterized in that the corner edge of arcuate or chamfered on the corner between the two ridge portions are formed. 5. A flat lands are formed on the ridge portion of the upper surface, the throw-away tip according to any one of claims 1 to 4, characterized in that the breaker groove on the inside is provided. Wherein said planar land, throw-away according to any one of claims 1 to 5, characterized in that the minor cutting edge and width than other portions at the portion of the corner subsequent is larger Chips. 7. A ridge line at a boundary between the sub cutting edge and the main cutting edge,
Claim, characterized in that notches are provided 1 to 6
The throwaway tip according to any one of the above. Wherein said cut-out, the throw-away tip according to claim 7, characterized in that it is formed by cutting the top and sides in an arc shape or a polygonal shape. 9. A polygonal plate-like shape, wherein a ridge on the upper surface facing the seating surface forms a cutting edge and the upper surface is a rake surface, and a side surface from the seating surface to the upper surface is a flank surface. In a throw-away type cutter, wherein the throw-away tip has an axial rake angle set to a positive angle and a radial rake angle set to a negative angle, the throw-away tip is any one of claims 1 to 8 . And the main flank first flank is located at a position above the center when the cutter body is viewed from the front, and the front and rear ends of the main cutting edge located on the outer peripheral side are the cutter body. A throw-away type cutter having a same radius of rotation about a rotation axis of the cutter. 10. A two side receiving portion crossing each other in the chip mounting portion formed on the tip outer peripheral side of the cutter, and the minor cutting edge flank of the cutting insert, the major cutting edge of the adjacent sides The indexable cutter according to claim 9 , wherein the second flank is abutted. 11. The flank of the sub cutting edge of the throw-away tip abuts on a side receiving portion of the tip mounting portion which faces in the radial direction, and the second cutting edge flank of the main cutting edge contacts the side receiving portion which faces in the axial direction.
The indexable cutter according to claim 10 , wherein a flank is abutted.