JP2001219315A - Throw-away tip and throw-away type roll cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a throw-away tip and a throw-away type roll cutting tool capable of increasing the accuracy of a rectangular wall surface without forming a projected wall surface due to a failure to cut off the surface on the rectangular wall surface of a cut material to be machined. SOLUTION: Curved cutting blade parts 19 and 20 forming projected curves as viewed from the front and having different heights from a seat surface formed of start ends 19a and 20a on a side nearer an auxiliary cutting blade positioned on both adjacent sides of a nose 16 as viewed from the side and final ends 19b and 20b on a side apart from the auxiliary cutting blade are formed in each main cutting blade 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a throw-away insert mounted on a milling tool such as a face mill or an end mill, and a throw-away milling tool provided with the same, and more particularly to a throw-away milling tool. The present invention relates to a throw-away insert which is mounted on the outer periphery of the tip of a cutting tool and can perform right-angle cutting (90-degree shoulder wall cutting) of a work material.

[0002]

2. Description of the Related Art Conventionally, as this kind of indexable insert, for example, as shown in FIGS. 10 and 11, mounted on the outer peripheral side of a milling cutter 1 such as a face mill.
There is a square chip 2 when viewed from the front. As shown in FIG. 10, the throw-away tip 2 has an upper surface 4 opposed to a lower surface 3 forming a seating surface.
Is a plane inclined outward from the lower surface 3 toward the upper surface 4. At the ridgeline where each side surface 5 and top surface 4 intersect,
A main cutting edge 6 is formed, and a sub cutting edge 7 is formed near each corner 4a on the same ridge line as the main cutting edge 6. The upper face 4 forms a rake face, and each side face 5
Form 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 formed on the same surface (side surface 5). A screw hole 8 is formed in the center of the upper surface 4 so as to penetrate the upper and lower surfaces to mount and fix the chip 2 to a throw-away type rolling tool such as the milling cutter 1 or the like.

When such a throw-away tip 2 is mounted on a tip mounting seat formed on the outer periphery of the tip of the milling cutter 1, a positive angle is formed so as to form a positive angle with respect to the rotation axis L of the cutter body. The cutter is fixedly mounted so as to have an axial rake angle and a negative radial rake angle with respect to a radial axis M (not shown) of the cutter body. Then, the main cutting edge 6 located on the outer peripheral side is cut so as to form the right-angled wall f of the workpiece W, and at the same time, the sub cutting edge 7 forms a cutting angle based on the positive axial rake angle and the negative radial rake angle. Since the cutting bottom surface is finished in the cut state, it is possible to perform right angle cutting.

[0004]

However, the above-described indexable insert 2 has the following problems. That is, since the positive axial rake angle and the negative radial rake angle described above must be provided for the throw-away tip 2, the main cutting edge 6 of the throw-away tip 2 has The distance from the rotation axis L of the cutter body is not equal, and a gap g as shown in FIGS. 12 and 13 is generated with respect to the right-angled wall surface f of the work material W to be processed. Naturally, this gap g portion is left uncut, and a protruding projecting wall surface f ′ is formed with respect to the originally formed right-angled wall f, which hinders the improvement of the cutting accuracy of the right-angled wall f. Had a problem,

The present invention has been made in view of the above circumstances, and has the following objects. That is, the present invention provides a throw-away insert and a throw-away type rolling tool capable of improving the right-angle wall accuracy without forming a projecting wall surface due to uncut portions on the right-angle wall surface of the work material to be machined. Aim.

[0006]

Means for Solving the Problems The indexable insert and indexable milling tool of the present invention employ the following means to solve the above-mentioned problems. That is, the throwaway tip according to claim 1, the main cutting edge and the sub cutting edge are provided at a ridge portion of the upper surface facing the seating surface, and the upper surface is a rake surface, and the upper surface is a rake surface. In the throw away tip having a flank facing the side, the ridge portion has four sides forming a square when viewed from the front, and each of the sides has the main cutting edge and the sub cutting edge. Are formed continuously, and the sub-cutting edge formed on one side is located across the corner with the main cutting edge formed on the adjacent side adjacent thereto. Each of the main cutting edges has a convex curve when viewed from the front, and, when viewed from the side, a side closer to the sub-cutting edge located on an adjacent side across the corner. A curved cutting edge having a different height from the seating surface at the start end and at the end on the distant side is formed. Characterized in that it is. According to the indexable insert according to claim 1, when the insert is mounted on an indexable milling tool to perform a right-angled cutting (90-degree shoulder wall cutting) of the work material, the main cutting edge is viewed from the front. The radius distance from the rotation axis of the throw-away type rolling tool is a convex curve that is substantially equal over each point of the entire length thereof, and a gap is generated between the right-angled wall surface to be originally processed at the time of cutting. There is no.

The indexable insert according to claim 2 is
The indexable insert according to claim 1, wherein the main cutting edge is formed with a plurality of the curved cutting edge portions. According to the indexable insert according to the second aspect, by adopting a configuration in which a plurality of curved cutting edge portions are formed in a row on the main cutting edge, the radius of curvature when these curved cutting edge portions are viewed from the side, The side close to the secondary cutting edge and the side remote from it can be different. In this case, by adjusting the respective radii of curvature, for example, the axial angle on the side closer to the sub cutting edge can be reduced and the axial angle on the side farther away can be adjusted.

[0008] The throw away tip according to claim 3 is:
3. The indexable insert according to claim 1, wherein each of the main cutting edges is formed so as to be gradually separated from an extension of the sub cutting edge located on the same side when viewed from the front. It is characterized by the following. According to the indexable insert according to the third aspect, when the insert is mounted on an indexable milling tool to perform a right-angle cutting (90-degree shoulder wall cutting) of a work material, the sub cutting edge is cut and finished. The main cutting edge on the same side does not contact the finished surface after performing.

[0009] The indexable insert according to claim 4 is:
The throw-away tip according to any one of claims 1 to 3, wherein the corner portion has a convex curve when viewed from the front, and the seating portion moves from one end to the other end when viewed from the side. A nose curve cutting edge part whose height from the surface is gradually reduced is formed. According to the indexable insert according to the fourth aspect, since the corner portion is formed into a convex curve in a plan view, the strength of the blade can be improved as compared with a case where the corner portion is formed into an acute tip shape. Furthermore, when the corner portion is viewed from the side, the height from the seating surface is gradually reduced from one end side to the other end side, so that the entire corner portion hits the cut surface when cutting the work material. Rather, the cutting edge gradually hits from a high place to a low place from the seating surface,
The impact applied to the corners can be reduced to improve the strength of the cutting tool at the corners.

[0010] The throwaway tip according to claim 5 is:
5. The indexable insert according to claim 1, wherein the flank including the main cutting edge is a torsion surface in which an angle between the flank and the seating surface gradually decreases from the end side to the start side. 6. It is characterized by having. According to the indexable insert according to the fifth aspect, since the clearance angle at the start end side can be made smaller than the clearance angle at the end side, the occurrence of an excessive clearance angle at the start end side of the main cutting edge can be prevented. It becomes possible.

According to a sixth aspect of the present invention, there is provided a throw-away milling tool, wherein the throw-away insert is mounted such that the radial rake angle becomes a negative angle and the axial rake angle becomes a positive angle. In a milling tool, the throw-away insert is the throw-away insert according to any one of claims 1 to 5. According to the indexable rolling tool according to the sixth aspect, it is possible to obtain the same operation as the operation according to any one of the first to fifth aspects.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a throw-away insert of the present invention and a throw-away type milling tool provided with the same will be described below, but it is to be understood that the present invention is not limited to these embodiments. Of course. In addition, FIG.
FIG. 2 is a perspective view showing one embodiment of the throw-away tip of the present invention, FIG. 2 is a front view of the throw-away tip, and FIG.
FIG. 4 is a side view as seen from the line side, and FIG. 4 is a rear view of the same throw-away tip as seen from the line CC in FIG. FIG. 5 is a diagram showing a main part of the throw-away tip, (a) is an enlarged view of a portion D in FIG. 2, and (b)
FIG. 4 is an enlarged view of a portion E in FIG. 3. FIG. 6 is a view of the throw-away tip as viewed from the arrow F side in FIG.
7 is a view of the throw-away tip as viewed from the arrow G side in FIG. 1, and FIG. 8 is a diagram showing a main part of the throw-away tip, and is an enlarged view of a H part of FIG. . Also,
FIG. 9 is a cross-sectional view showing a work material wall surface cut at right angles by the indexable insert.

As shown in FIGS. 1 to 4, the indexable insert 10 of the present embodiment has a main cutting edge 12 and a sub cutting edge 13 formed at a ridgeline on an upper surface facing a seating surface 11 as a lower surface. The upper surface is a rake surface 14, the four circumferential side surfaces inclined outward from the seating surface 11 toward the upper surface are flank surfaces 15, and the main cutting edge 12 and the sub cutting edge are sandwiched by a nose 16 which is a corner portion. It has a substantially square flat plate shape on which the blades 13 are arranged. In the center of the rake face 14, the throw-away tip 1 penetrates the upper and lower faces.
A screw hole 17 is provided for mounting and fixing 0 to a throw-away type rolling tool (not shown) such as a milling cutter.

The ridge portion has four side edges 18 which form a square when viewed from the front as shown in FIG. 2, and a main cutting edge 12 and a sub cutting edge 13 are continuously connected to each of these side edges 18. Formed,
The sub cutting edge 13 formed on one side 18 is the main cutting edge 12 formed on the adjacent side 18 adjacent thereto.
And the nose 16. The indexable insert 10 can be selected from four mounting directions for the indexable milling tool. That is, the sub-cutting edge 13 located on the lower right side of the drawing and the main cutting edge 12 located on the right side of the drawing shown in FIG.
When performing 0 degree shoulder wall shaving), the selected minor cutting edge 13
Is substantially parallel to the cutting surface of the throw-away milling tool in the transverse feed direction, and at the same time, the direction in which the selected main cutting edge 12 faces the outer peripheral side of the throw-away milling tool (see FIG. 1). Then, it is mounted and fixed to the above-mentioned indexable milling tool. When the sharpness of the main cutting edge 12 and the sub cutting edge 13 deteriorates with use, the mounting direction of the indexable insert 10 to the indexable milling tool is rotated by 90 degrees around the screw hole 17. Then, it is possible to select another sub-cutting edge 13 and another main cutting edge 12 and perform cutting with them. By changing the mounting direction in this way, the same throw-away tip 10 can be used four times.

As shown in FIGS. 5A and 5B, each main cutting edge 12 is composed of two continuous curved cutting edges 19 and 20. That is, the curved cutting edge 19 is formed as shown in FIG.
And a convex curve having a true R of a radius of curvature r1 (here, the true R indicates a curve having a constant radius of curvature that forms a perfect circle; the same applies hereinafter) when viewed from the front as shown in FIG. FIG.
When viewed in a side view shown in FIG. 3B, the seating surface faces the end 19b on the side away from the starting end 19a on the side close to the sub-cutting edge 13 located on the adjacent side 18 with the nose 16 interposed therebetween. 1
A convex curve having a radius of curvature r2 in which the height h1 from 1 gradually increases. Also, the curved cutting edge 20 is shown in FIG.
5B, a convex curve having a true radius R of a curvature radius r3 when viewed in a front view, and a start end on a side close to an adjacent curved cutting edge 19 when viewed in a side view shown in FIG. The height h1 from the seating surface 11 gradually decreases toward the terminal end 20b away from the side 20a and has a convex curve with a radius of curvature r4.

Therefore, the height h1 is different between the starting end 19a of the curved cutting edge 19 and the end 20b of the curved cutting edge 20, and the entire curved cutting edges 19, 20 (from the starting end 19a to the end 20b). That is, the general shape of the main cutting edge 12 as a whole) has a seating surface 1 while drawing one convex curve.
It has a curved shape that warps to approach 1. The shape of the curved cutting edges 19 and 20 as viewed from the side may be such that the height of the terminal end 20b is lower than that of the start end 19a, and two convex curves of the radii of curvature r2 and r4 are combined. The shape is not limited to this, and a linear shape or a concave curve shape may be adopted. Further, the configuration is not limited to the two curved cutting edges 19 and 20, and a configuration in which three or more curved cutting edges are combined in the main cutting edge 12 may be adopted.

As shown in FIG. 5A, each main cutting edge 12
Is formed so as to gradually separate from the extension line a of the sub cutting edge 13 located on the same side 18 when viewed from the front. This is because, when the throw-away insert 10 is mounted on the throw-away type milling tool to perform the right-angle cutting (90-degree shoulder wall cutting) of the work material, the sub cutting edge 13 performs the cutting finish. This is to prevent the main cutting edge 12 on the same side 18 from contacting the finished surface to damage the finished surface.

Each nose 16 has a convex curve having a true radius R of curvature r5 when viewed from the front as shown in FIG. 5 (a), and when viewed from the side as shown in FIG. A nose curve cutting edge portion 21 is formed in which the height h2 from the seating surface 11 gradually decreases from the one end 21a side to the other end 21b side. Then, as shown in FIG.
The height h2 of the nose curve cutting edge portion 21 is higher than the sub cutting edge 13 at one end 21a and the same height as the sub cutting edge 13 at the other end 21b.

As shown in FIG. 5 (b), each flank 15 including each main cutting edge 12 is provided with the end 2 of the curved cutting edge 20.
An angle (the angle θ1 shown in FIG. 3) between the 0b side and the starting end 19a side of the curved cutting edge portion 19 (the angle θ1 shown in FIG. 3. An imaginary line HL shown in FIG. The imaginary line VL indicates an extension line on the torsion surface 22 described later). That is, a wall surface formed between the straight line 22a connecting the start end 19a and the end 20b and the main cutting edge 12 is a torsion surface 22, and a clearance angle formed by the torsion surface 22 is from the end 20b to the start end. A twist surface 22 is formed so as to gradually decrease toward the 19a side. As a result, the twisted surface 22 is not a flat surface but a twisted surface. The twisted surface 22 is not formed only on the wall surface formed between the straight line 22 a and the main cutting edge 12, but is formed on the main cutting edge 12 and the seating surface 11.
The entire surface (region 22b shown in FIG. 3) formed between them may be the twisted surface 22. In this case, the angle formed by the torsion surface 22 and the seating surface 11 is, instead of the angle θ1,
The angle becomes θ1 ′ shown in FIG. 3 (the virtual line VL becomes the virtual line VL ′ shown in FIG. 3).

When a workpiece (not shown) is to be cut at right angles using the above-described throw-away insert 10, the throw-away insert 10 is attached to a throw-away type milling tool such as a milling cutter (not shown). ) Is attached to the tip mounting seat formed on the outer periphery of the tip, and as shown in FIG. 6 and FIG.
A positive axial rake angle α so as to form a positive angle with respect to the axis, and a negative radial rake so as to form a negative angle with respect to the radial axis M of the throw-away type milling tool. It is fixedly attached so as to have an angle β. And the main cutting edge 12 located on the outer peripheral side
The cutting is performed so as to form the right-angled wall surface (right-angled wall surface f described in the related art) of the work material, and at the same time, the sub-cutting blade 13 finishes the cutting bottom surface.

At this time, the main cutting edge 12 has a convex curve combined with the curvature radius r1 and the curvature radius r3 when viewed from the front as shown in FIG. The radial distance from the rotation axis L of the milling tool is
As shown in FIG. 8, the convex curve of the true R is substantially equal over each point of the entire length of the main cutting edge 12, and the gap g may be generated with respect to the right-angled wall f to be originally machined at the time of cutting. Therefore, without forming the projecting wall surface f ′ due to uncut portions on the right-angled wall surface f of the workpiece W,
It is possible to improve the right-angle wall accuracy. Therefore, it is possible to accurately cut the right-angled wall f without swelling as shown in FIG.

Further, when the main cutting edge 12 is viewed from the side, the main cutting edge 12 is located on the side away from the starting end 19a on the side close to the sub cutting edge 13 located on the adjacent side 18 with the nose 16 interposed therebetween. Since the height h1 from the seating surface 11 is curved toward the end 20b so as to gradually decrease, the indexable insert 10 can be attached to the indexable milling tool at a normal axial angle. Even if it is attached, a larger axial angle α can be earned. By securing such a large axial angle α, the sharpness can be improved, and the impact applied to the main cutting edge 12 can be suppressed low to reduce the possibility of breakage. In addition, the curved shape when the curved cutting edge portions 19 and 20 are viewed from the front is set to true R, so that the throw-away tip 10 can be compared with the case where the curved shape is complicated.
Is easy to manufacture and cost reduction is possible.

Each of the main cutting edges 12 when viewed from the front is
By adopting a configuration that is formed so as to be gradually separated from the extension line a of the sub cutting edge 13 located on the same side 18, the indexable insert 10 is mounted on the indexable milling tool and Right angle cutting of cutting materials (90 degree shoulder wall cutting)
Is performed, since the main cutting edge 12 on the same side does not contact the finished surface after the sub cutting edge 13 has performed the cutting finish, it is possible to prevent the finished surface from being damaged. It becomes possible.

Each nose 16 is connected to the nose curve cutting edge 2.
By setting it to 1, since it becomes a convex curve when viewed from the front, the blade strength of each nose 16 can be improved as compared with the case of having an acute tip shape. Furthermore, when the nose 16 is viewed from the side, the height h2 from the seating surface 11 is gradually reduced from the one end 21a side to the other end 21b side, so that the nose 16 The cutting edge does not hit as a whole but rather the height h2 from the seating surface 11 gradually hits from a high position to a low position, so the impact applied to the nose 16 can be reduced to improve the blade strength. it can. By combining the above two points, it is possible to further improve the strength of the nose portion 16.

The main cutting edge 12 has two curved cutting edge portions 1.
By adopting a configuration in which the curved cutting edges 9 and 20 are continuously formed, the radius of curvature r when these curved cutting edges 19 and 20 are viewed from the side is shown.
2, r4 can be made different between the side closer to the sub-cutting edge 13 on the adjacent side 18 and the side remote from it. In this case, by adjusting each radius of curvature,
For example, it is possible to make adjustments such as reducing the axial angle on the side adjacent to the sub-cutting edge 13 on the side 18 and increasing the axial angle on the side remote from the sub-cutting edge 13.

Each flank 15 including each main cutting edge 12
In addition, by adopting a configuration in which the angle θ1 formed with the seating surface 11 with the seating surface 11 gradually decreases from the terminal end 20b side to the start end 19a side, the starting end 19a side is located closer to the start end 19a than the clearance angle of the terminal end 20b side. Since the clearance angle can be reduced, an excessive clearance angle between the start end 19a and the end 19b of the main cutting edge 12 (the blade angle becomes excessively thin) is prevented, and the clearance between the start end 19a and the end 19b of the main cutting edge 12 is prevented. It is possible to secure a sufficient blade strength of the portion.

[0027]

According to the indexable insert of the present invention, the ridge portion has four sides forming a square when viewed from the front, and each of these sides has a main cutting edge and a sub cutting edge. The blades are formed continuously, and the sub-cutting edge formed on one side is located across the main cutting edge and the corner formed on the adjacent side adjacent thereto, Each main cutting edge has a convex curve when viewed from the front, and, when viewed from the side, is separated from the starting edge on the near side with respect to the sub-cutting edge located on the adjacent side with the nose therebetween. A configuration is adopted in which a curved cutting edge portion having a different height from the seating surface is formed at the end on the opposite side. When a throw-away insert having this configuration is mounted on a throw-away type rolling tool to perform a right-angle cutting (90-degree shoulder wall cutting) of a work material, the main cutting blade is viewed from the front and the throw-away type rolling tool is used. The radius of the cutting tool from the axis of rotation is a convex curve that is substantially the same over each point along its length, and there is no gap between the right-angled wall surface that should be machined during cutting. It is possible to improve the accuracy of the right-angled wall surface without causing the formation of a projecting wall surface due to the uncut portion of the right-angled wall surface.

Furthermore, when the main cutting edge is viewed from the side, for example, the height from the seating surface gradually increases toward the end farther from the starting end closer to the sub cutting edge on the adjacent side. When the insert is mounted on a throw-away type milling tool with a normal axial angle, a larger axial angle can be obtained. When such a large axial angle can be ensured, the sharpness can be improved, and the impact applied to the main cutting edge can be suppressed low to reduce the possibility of breakage.

According to the indexable insert according to the second aspect of the present invention, by adopting a configuration in which a plurality of curved cutting edges are formed in a row on the main cutting edge, the curved cutting edges can be viewed from the side. It is possible to make the radius of curvature different between the side closer to the sub-cutting edge on the adjacent side and the side farther away. In this case, by adjusting the respective radii of curvature, for example, with respect to the sub cutting edge on the adjacent side, it is possible to reduce the axial angle on the near side and increase the axial angle on the distant side. Becomes

According to the indexable insert of the third aspect, when viewed from the front, each main cutting edge is formed so as to be gradually separated from the extension of the sub cutting edge located on the same side. By adopting the configuration, the sub cutting edge finished the cutting when the insert was mounted on the indexable milling tool and the workpiece was cut at right angles (90 degrees shoulder wall cutting). Since the main cutting edge on the same side does not come into contact with the subsequent finished surface, it is possible to prevent the finished surface from being damaged.

Further, the throw-away tip according to claim 4 has a convex portion at the corner portion when viewed from the front and a height from the seating surface from one end to the other end when viewed from the side. A configuration is used in which a nose curve cutting edge portion that gradually decreases in height is formed. According to this configuration, since the corner portion is formed as a convex curve when viewed in a plan view, the blade strength can be improved as compared with the case where the corner portion has an acute-angled tip shape. Furthermore, when the corner portion is viewed from the side, by gradually lowering the height from the seating surface from one end side to the other end side, the entire corner portion hits the cut surface when cutting the work material. Instead, the blade edge gradually comes in contact with the height from the seating surface to a high place to a low place. Therefore, it is possible to reduce the impact applied to the corner portion and improve the strength of the blade at the corner portion. By having the above two points, the strength of the corner portion can be further improved.

Further, according to the indexable insert according to the fifth aspect, the flank including the main cutting edge is formed as a twisted surface whose angle with the seating surface gradually decreases from the end to the start. By doing so, the clearance angle at the start end side can be made smaller than the clearance angle at the end side, so that an excessive clearance angle at the start end side of the main cutting edge is prevented, and sufficient blade strength at the main cutting edge start end portion is obtained. It is possible to secure.

According to the indexable turning tool of the sixth aspect, it is possible to obtain the same effects as those of the first to fifth aspects.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a throw-away tip of the present invention.

FIG. 2 is a front view of the throw-away tip.

FIG. 3 is a side view of the throw-away tip as viewed from the line BB in FIG. 2;

FIG. 4 is a rear view of the throw away tip as seen from the line CC in FIG. 3;

5A and 5B are diagrams showing a main part of the throw-away tip, wherein FIG. 5A is an enlarged view of a portion D in FIG. 2, and FIG.
FIG. 4 is an enlarged view of a portion E in FIG. 3.

FIG. 6 is a view of the throw-away tip as viewed from an arrow F side in FIG. 1;

FIG. 7 is a view of the throw away tip as viewed from an arrow G side in FIG. 1;

8 is a diagram showing a main part of the throw-away tip, and is an enlarged view of a portion H in FIG. 7;

FIG. 9 is a cross-sectional view showing a work material wall surface that has been cut at right angles by the indexable insert.

FIG. 10 is a perspective view showing a conventional throw-away tip.

FIG. 11 is a side cross-sectional view showing a cutting state by a conventional throw-away type rolling tool equipped with the same throw-away insert.

FIG. 12 is a view showing a cutting state by the throw-away type rolling tool equipped with the throw-away tip, and is a view as viewed from the line AA in FIG. 11;

FIG. 13 is a cross-sectional view showing a work material wall surface that has been cut at right angles by the indexable insert.

[Explanation of symbols]

10 ... throw-away tip, 11 ... seating surface, 12 ...
・ Main cutting edge, 13 ・ ・ ・ Sub cutting edge, 14 ・ ・ ・ Rake face, top face, 1
5 ... side surface, flank surface, 16 ... nose part (corner part),
18 ... side edge, 19, 20 ... curved cutting edge part, 19a, 20
a: start end on the side close to the sub cutting edge, 19b, 20b ... end on the side away from the end, 21 ... nose curve cutting edge part, 21a ... one end,
21b: the other end, 22: twisted surface, a: extension line, h
1, h2: height, α: axial rake angle, β: radial rake angle, θ1, θ1 ': angle formed with the seating surface

Claims (6)

[Claims] 1. A main cutting edge and a sub cutting edge are provided on a ridge portion of an upper surface opposed to a seating surface, 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 the throw-away insert, the ridge portion has four sides forming a square when viewed from the front, and the main cutting edge and the sub cutting edge are continuously formed on each of these side edges. The sub-cutting edge formed on one side is located across the main cutting edge and the corner formed on the adjacent side adjacent to the sub-cutting edge. Is a convex curve when viewed from the front, and, when viewed from the side, the starting end on the side close to the sub-cutting edge located on the adjacent side across the corner, and the end on the side distant from the side. Characterized in that a curved cutting edge portion having a different height from the seating surface is formed by Away tip. 2. The indexable insert according to claim 1, wherein the main cutting edge is formed with a plurality of the curved cutting edges. 3. The indexable insert according to claim 1, wherein each of the main cutting edges gradually separates from an extension of the sub cutting edge located on the same side when viewed from the front. A throw-away tip, characterized in that it is formed on 4. The indexable insert according to claim 1, wherein the corner portion has a convex curve when viewed from the front and from one end to the other end when viewed from the side. A throw-away tip, wherein a nose curve cutting edge portion whose height from the seating surface gradually decreases toward the center is formed. 5. The indexable insert according to claim 1, wherein an angle between the flank including the main cutting edge and the seating surface from the end to the start is gradually reduced. A throwaway tip characterized by a twisted surface. 6. A throw-away type milling tool, wherein the throw-away insert is mounted such that the radial rake angle becomes a negative angle and the axial rake angle becomes a positive angle, wherein the throw-away insert comprises: A throw-away type milling tool, which is the throw-away insert according to any one of claims 1 to 5.