WO2015141695A1

WO2015141695A1 - Cutting insert and cutting edge-replaceable rotary cutting tool

Info

Publication number: WO2015141695A1
Application number: PCT/JP2015/057951
Authority: WO
Inventors: 哲司小宮山
Original assignee: 株式会社タンガロイ
Priority date: 2014-03-18
Filing date: 2015-03-17
Publication date: 2015-09-24
Also published as: JP6004301B2; JPWO2015141695A1

Abstract

The present invention provides a cutting insert (1) that has a first end face (2), a second end face (3) that faces the first end face (2), and a circumferential side surface (4) that connects the first end face (2) and the second end face (3) together, and the cutting insert (1) is equipped with at least two first end-face-side cutting edges (8, 10) that are disposed on ridge line sections where the first end face (2) and the circumferential side surface (4) intersect with each other. The first end-face-side cutting edges (8, 10) are each divided into two or more cutting edge sections (12) by means of one or more nicks (11). The cutting edge sections (12) of the first end-face-side cutting edges (8, 10) all have different lengths from one another.

Description

Cutting insert and cutting edge exchangeable rotary cutting tool

The present invention relates to a cutting insert and a blade-tip-exchange-type rotary cutting tool equipped with the cutting insert. More specifically, the present invention relates to a cutting insert for a ball end mill and a blade end replaceable ball end mill having the same.

Currently, as a blade end replaceable ball end mill, a three-blade type as disclosed in Patent Document 1 is known. In this ball end mill, only one type of cutting insert is used. The cutting insert has a shape in which two arcuate curves are opposed to each other so as to spread outward in a plan view (hereinafter also referred to as “leafy leaves”), and has a first end face. And a negative-type side surface in which a cutting edge is formed on both the second end surface and a positive-type side surface in which a cutting edge is formed only on the first end surface. Here, the negative-type side surface means a side surface having a so-called zero clearance angle. Further, the positive side surface refers to a side surface to which a positive clearance angle is given from the first end surface toward the second end surface. Therefore, the cutting insert of Patent Document 1 has a total of three cutting edges, two on the first end face and one on the second end face. Therefore, it is possible to cover all three blades with this cutting insert alone.

Thus, in the cutting insert of patent document 1, although the negative type side surface in which the cutting edge is formed in both the 1st end surface and the 2nd end surface is formed, it is formed in the negative type side surface. The cutting edge that is present generally has a higher cutting resistance than the cutting edge formed on the positive side. Therefore, in the said cutting insert, in order to reduce cutting resistance, several nicks are formed in the negative type side surface. The cutting resistance is reduced by the nick subdividing the chips.

International Publication No. 2013/191259

Incidentally, in recent years, there has been an increasing demand for cutting under more severe cutting conditions in search of high-efficiency machining that increases the amount of cutting per unit time. Under such severe conditions, the cutting insert of Patent Document 1 may not sufficiently reduce the cutting resistance. As a method for solving this problem, in the cutting insert of Patent Document 1, cutting is performed by forming a nick not only on the cutting edge formed on the negative type side surface but also on the cutting edge formed on the positive type side surface. A way to further reduce the resistance can be considered. However, in that case, the following problems may occur.

That is, the cutting insert of Patent Document 1 is mounted so as to be inclined in a side view with respect to the rotation center axis of the tool body, and the cutting edge is from a portion located on the front end side or the rear end side of the tool body. It is designed to bite into the work material in order. For this reason, resonance may occur when the plurality of cutting edge portions divided by the nick periodically bite or leave the work material from one to the next periodically at equal intervals. When the cutting edge resonates, chatter occurs, which may lead to a reduction in cutting performance and a deterioration in the surface roughness of the machining surface.

The present invention has been made in view of the above problems, and a cutting insert capable of reducing cutting resistance by nicking and reducing the occurrence of chatter, and a blade-cuttable rotary cutting tool equipped with the cutting insert. The purpose is to provide.

The present invention includes a first end surface 2, a second end surface 3 that faces the first end surface 2, and a peripheral side surface 4 that connects the first end surface 2 and the second end surface 3. The cutting insert 1 is provided with at least two first end face

side cutting edges

8 and 10 at the intersecting ridge line portion with the peripheral side surface 4, and each of the first end face

side cutting edges

8 and 10 has one or more nicks. 11 is divided into two or more cutting edge portions 12, and all the cutting edge portions 12 of the

cutting edges

8 and 10 on the first end face side have different lengths.

Furthermore, the present invention provides a tool body 21 having a rotation center axis O extending from the distal end side to the proximal end side, a plurality of insert seats 22 provided on the distal end side of the tool body 21, and a detachable attachment to the insert seat 22. The cutting insert is a rotary cutting tool 20 having a replaceable cutting edge, and this cutting insert is the cutting insert 1, and the cutting insert 1 corresponds to a predetermined positive or negative axial rake. It is attached to an insert seat.

According to the present invention, by changing the length of the cutting edge portion divided by the nick, the periodicity of the biting interval of the cutting edge portion to the work material can be lowered. Therefore, since it becomes difficult for resonance to occur in the cutting edge, chatter can be greatly suppressed.

FIG. 1 shows a perspective view of a cutting insert according to an embodiment of the present invention. FIG. 2A shows a top view of the cutting insert of FIG. 2B shows a side view when viewed from the side surface 4b side of the cutting insert of FIG. FIG. 2C shows a side view when viewed from the side surface 4a side in the cutting insert of FIG. FIG. 2D shows a bottom view of the cutting insert of FIG. FIG. 3 shows a top view of the cutting insert of FIG. FIG. 4: shows the perspective view seen from the direction which the 1st insert seat of the blade-tip-exchange-type rotary cutting tool which concerns on one Embodiment of this invention becomes a near side. FIG. 5 shows a perspective view of a tool body used in the cutting edge exchange type rotary cutting tool of FIG. FIG. 6 shows an end view of the cutting edge exchange type rotary cutting tool of FIG. 4 as viewed from the front end side. FIG. 7 is a side view as seen from the direction in which the first insert seat of the tip portion of the blade-tip-exchange-type rotary cutting tool of FIG. FIG. 8: shows the perspective view seen from the direction which the 2nd insert seat of the blade-tip-exchange-type rotary cutting tool which concerns on one Embodiment of this invention becomes a near side. FIG. 9: shows the perspective view seen from the direction which the 3rd insert seat of the blade-tip-exchange-type rotary cutting tool which concerns on one Embodiment of this invention becomes a near side. FIG. 10 is a side view as seen from the direction in which the second insert seat at the front end portion of the blade-tip-exchange-type rotary cutting tool in FIG. 4 is in front. FIG. 11 shows a side view as seen from the direction in which the third insert seat of the tip portion of the blade-tip-exchange-type rotary cutting tool of FIG. 4 is in front.

Now, an embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIGS. 1 and 2A to 2D, the cutting insert 1 of the present embodiment has a substantially tree-like shape in which two arcuate curves are opposed to each other and their ends are connected in plan view. The first end surface 2, the second end surface 3 having substantially the same shape as the first end surface 2 and provided substantially parallel to the first end surface 2, and the first end surface 2 and the second end surface 3. It is basically composed of peripheral side surfaces 4 to be connected. This “leafy tree” means that two arc-shaped curves are opposed to each other, their ends are connected to each other, spread from one connected end toward the center, and closed toward the other end. It means the shape. In other words, the “leafy shape of a tree” is a shape in which the ends are connected to each other so that each arcuate curve spreads outward. Further, a mounting hole 5 penetrating between the first end surface 2 and the second end surface 3 is provided in the approximate center between the first end surface 2 and the second end surface 3. The first end face 2 has two

tops

6, 7. Each of the

top portions

6 and 7 has a top portion corresponding to the second end surface 3 in the central axis direction of the mounting hole 5. The same reference numerals are used for the top portions of the second end surface 3 corresponding to the

top portions

6 and 7 of the first end surface 2. The peripheral side surface 4 has an edge extending between the top 6 of the first end surface 2 and the top 6 of the second end surface 3 and an edge extending between the top 7 of the first end surface 2 and the top 7 of the second end surface 3. The first side surface 4a and the second side surface 4b are separated from each other. Since the first side surface 4a is a side surface portion that intersects the first end surface 2 and the second end surface 3 at a substantially right angle, the first side surface 4a is generally arcuate in plan view. Since the second side surface 4b intersects the first end surface 2 at an acute angle while the second side surface 4b intersects an obtuse angle with respect to the second end surface 3, in a plan view from the second end surface side, It is represented as an arcuate surface having a certain width. That is, the first side surface 4 a is in a so-called negative relationship with respect to the first end surface 2 and the second end surface 3. Further, the second side surface 4 b is in a so-called positive relationship with the first end surface 2.

In the present embodiment, as described above, the first side surface 4a and the second side surface 4b are directly connected at the

top portions

6 and 7 of the first end surface 2 and the second end surface 3, but the present invention is limited to this configuration. It will never be done. That is, even when the first end surface 2 and the second end surface 3 have a shape in which the

top portions

6 and 7 of the first end surface 2 and the second end surface 3 are notched in a straight line shape or a curved shape in a plan view. I do not care. In this case, the first side surface 4a and the second side surface 4b are not directly connected.

The arcuate intersection ridgeline between the first end face 2 and the first side face 4a functions as the cutting edge 8. The cutting edge 8 functions as an outer peripheral edge in the ball end mill. The outer peripheral edge is a cutting edge that is arranged so as not to cut to the tool rotation axis when the cutting insert is mounted on the ball end mill. The arcuate intersection ridge line between the second end face 3 and the first side face 4 a also functions as the cutting edge 9. This cutting edge 9 also functions as an outer peripheral edge in the ball end mill. That is, the intersecting ridge line portion formed by the first side face 4a and the first end face 2 or the second end face 3 functions as an outer peripheral blade. On the other hand, the arcuate intersection ridge line between the second side face 4 b and the first end face 2 also functions as the cutting edge 10. This functions as a center blade in a ball end mill. The center blade is a cutting blade that is disposed so as to cut to a region near the tool rotation axis when the cutting insert is mounted on the ball end mill. Therefore, the cutting insert of this embodiment has the two

cutting edges

8 and 9 as an outer peripheral blade, and has the one cutting edge 10 as a center blade.

Since the first side surface 4a is a surface that intersects with the first end surface 2 and the second end surface 3 at a substantially right angle, the

cutting edges

8 and 9 are positioned in each intersecting ridge line portion in a substantially parallel relationship.

Here, the

cutting edges

8 and 10 can be regarded as cutting edges on the first end face side, and the cutting edge 9 can be regarded as cutting edge on the second end face side. The first end face 2 functions as a rake face for each of the two

cutting edges

8 and 10. In this case, the second end surface 3 functions as an insert fixing surface (contact surface) that contacts the tool body 21. When the cutting edge 8 formed by the first end face 2 and the first side face 4a acts as a cutting edge, the first side face 4a functions as a flank with a relief angle of 0 °, and the second side face 4b is connected to the tool body 21. It functions as an insert fixing surface that abuts. Moreover, when the cutting edge 10 by the 1st end surface 2 and the 2nd side surface 4b acts as a cutting edge, the 2nd side surface 4b which has a positive flank angle functions as a flank surface, and the 1st side surface 4a is the tool body 21. It functions as an insert fixing surface that abuts. On the other hand, the second end face 3 also functions as a rake face of the cutting edge 9 provided on the second end face 3. In this case, the first end surface 2 functions as an insert fixing surface that contacts the tool body 21. The first side surface 4 a functions as a clearance surface with a clearance angle of 0 °, and the second side surface 4 b functions as an insert fixing surface that comes into contact with the tool body 21. The “relief angle” herein refers to an angle of the cutting insert alone, and more precisely, a clearance surface with respect to a surface that is parallel to the central axis of the mounting hole 5 and can be defined to pass through the cutting edge. Refers to an angle.

In the present embodiment, a plurality of nicks 11 are formed on each of the first side surface 4a and the second side surface 4b. On the first side surface 4a, two nicks 11 are formed between the first end surface 2 and the second end surface 3 so as to intersect the

cutting edges

8 and 9 at a right angle in a side view. Yes. The nick 11 formed on the first side surface 4a has a linear groove shape having a substantially uniform width, and the depth is also substantially constant. Furthermore, on the second side surface 4b, two nicks 11 are formed so as to intersect the cutting edge 10 at a substantially right angle in a side view. The nick 11 formed on the second side surface 4b has such a shape that the width gradually decreases from the first end surface 2 side toward the second end surface 3 side and disappears in the middle of the second side surface 4b. Further, the nick 11 formed on the second side surface 4b gradually decreases in depth from the first end surface 2 side toward the second end surface 3 side, and in the middle of the second side surface 4b, It has a shape that matches. The number and shape of the nicks 11 are not limited to this, and can be appropriately changed without departing from the gist of the present invention. By these nicks 11, each of the

cutting edges

8, 9, and 10 is divided into three cutting edge portions 12, respectively.

Here, as shown in FIG. 3 (same as FIG. 2A), the six cutting edge portions 12 are respectively shown as a cutting edge portion in a plan view when the cutting insert 1 is viewed from the first end face 2 side. They are referred to as 12A, 12B, 12C, 12D, 12E, and 12F. The

cutting edge portions

12A, 12B, and 12C are formed on the first side surface 4a side, and the

cutting edge portions

12D, 12E, and 12F are formed on the second side surface 4b side. The lengths of the

cutting edge portions

12A, 12B, 12C, 12D, 12E, and 12F in FIG. 3 are defined as L1, L2, L3, L4, L5, and L6. Here, the “length” refers to the length of the arcuate curve along the cutting edge. Accordingly, the cutting edge 8 formed between the first side face 4a and the first end face 2 has cutting

edge portions

12A, 12B, and 12C having lengths L1, L2, and L3, respectively. Further, the cutting edge 10 formed between the second side surface 4b and the first end face 2 has cutting

edge portions

12D, 12E, and 12F having lengths L4, L5, and L6, respectively. Further, since the cutting edge 9 formed between the first side face 4a and the second end face 3 is symmetrical with the above-described cutting edge 8, the

cutting edge portions

12A and 12B having lengths L1, L2 and L3, respectively. , 12C. In the present embodiment, the lengths L1, L2, L3, L4, L5, and L6 of the

cutting edge portions

12A, 12B, 12C, 12D, 12E, and 12F are different from each other. That is, L1, L2, L3, L4, L5, and L6 are all different numerical values. In this way, the occurrence of chatter due to resonance of the cutting edge is suppressed by making the lengths of the cutting edge portions 12 different. The specific contents will be described later.

The periphery of the cutting edge of the cutting insert 1 is cemented carbide, cermet, ceramic, a material coated with these, an ultra-high-pressure sintered body containing diamond or cubic boron nitride, and an ultra-high-pressure firing containing cubic boron nitride. It can be made from a hard material such as a coating on the body. It is preferable that parts other than the cutting edge of the cutting insert 1 are also made of the same hard material.

Next, the three-blade replaceable ball end mill 20 to which the above-described cutting insert 1 is mounted will be described in detail with reference to the drawings.

As shown in FIGS. 4 to 7, the blade tip replaceable ball end mill 20 of this embodiment is a three-blade type, and is a substantially cylindrical tool having a rotation center axis O extending from the distal end side to the proximal end side. Three insert seats 22 are provided at the tip of the body 21. Further, three chip pockets 26 are provided adjacent to the three insert seats 22. The three insert seats 22 may be provided at substantially equal intervals in the circumferential direction in the front end view of the tool body 21, and the distances between them may be provided unevenly. These insert seats 22 are composed of a bottom surface 23 shaped like the outline of the cutting insert 1 described above, and a side surface 24 intersecting the bottom surface 23. The shapes of the bottom surface 23 and the side surface 24 differ depending on the respective insert seats 22. A screw hole 25 for attaching the cutting insert 1 is provided near the center of the bottom surface 23 of each insert seat 22. When the cutting insert 1 is attached to the insert seat 22, the cutting end 1 is arranged such that the first end surface 2 or the second end surface 3 contacts the bottom surface 23, and the first side surface 4 a or the second side surface 4 b contacts the side surface 24. At that time, as shown in FIG. 6, the three cutting inserts 1 are mounted so that the three

cutting edges

8, 9, and 10 are involved in the cutting. When the cutting edge 8 that functions as an outer peripheral edge on the first end face 2 side is mounted so as to be involved in cutting, the first end face 2 becomes a rake face, the first side face 4a becomes a flank face, and other faces It functions as a contact surface that comes into contact with the insert seat 22. When the cutting insert 1 is mounted so that the cutting edge 9 that functions as the outer peripheral edge on the second end face 3 side is involved in cutting, the second end face 3 is a rake face, and the first side face 4a is a flank face. Thus, the other surface functions as a contact surface in contact with the insert seat 22. When the cutting insert 1 is mounted so that the cutting edge 10 that functions as the central edge of the first end face 2 is involved in cutting, the first end face 2 becomes a rake face and the second side face 4b becomes a flank face. The other surface functions as a contact surface that comes into contact with the insert seat 22.

In other words, the orientation and shape of each of the three insert seats 22 are determined such that the cutting blades of the cutting insert 1 to be mounted are different from those mounted on the other two insert seats 22. . As shown in FIGS. 4 to 6, in the first insert seat 22a disposed closest to the axis O, the cutting edge 10a is positioned so as to be involved in cutting. Then, the cutting insert 1b attached to the second insert seat adjacent to the first insert seat 22a is positioned so that the cutting edge 8b is involved in cutting along the rotation direction K shown in FIG. 6 (FIG. 8). reference.). Then, along the rotation direction K, the insert 1c mounted on the adjacent third insert seat 22c is positioned so that the cutting edge 9c is involved in cutting (see FIG. 9).

Further, as shown in FIG. 7, when viewed in a predetermined direction perpendicular to the axis O of the tool body 21, the cutting insert 1 a is located on the tip side of the tool body 21. When the tip of the cutting insert 1a is perpendicular to the axis O and the surface P determined to pass through the cutting edge 10a is used as a reference, it is located at a position farthest from the surface P in the axis O direction as shown in FIG. Is the cutting insert 1b. Moreover, as shown in FIG. 11, what is located between the cutting insert 1b and the cutting insert 1a is the cutting insert 1c. In this way, the cutting inserts 1a to 1c are arranged so as to be slightly shifted in the body axis O direction.

The three cutting inserts 1 are mounted on the tool body 21 so as to have a positive or negative axial rake, respectively. That is, the cutting insert 1 is mounted so that the

cutting edges

8, 9, 10 are inclined at a positive or negative angle with respect to the rotation center axis O of the tool body 21 in a side view of the tool body 21. ing. This is the same even if any of the

cutting edges

8, 9, and 10 is involved in cutting. As shown in FIG. 7, the cutting insert 1 mounted so that the cutting edge 10 formed on the positive-type side surface 4b is involved in cutting is mounted with a positive axial rake. However, in the case of the two cutting inserts 1 mounted so that the

cutting edges

8 and 9 formed on the negative-type first side surface 4a are involved in cutting, a negative axial is used to ensure a true positive clearance angle. The cutting insert 1 is mounted by rake. Therefore, the

cutting edges

8, 9, 10 positioned in the direction in which each insert seat 11 is involved in cutting do not bite into the work material at the same time, but bite in order from the distal end side or the proximal end side of the tool body 21. It becomes.

As described above, a plurality of nicks 11 are formed on each of the

cutting edges

8, 9, and 10. When the cutting insert 1 is mounted on the tool body 21 in three ways, the nicks 11 are calculated and arranged so that they do not all overlap in the rotation trajectories of the

respective cutting edges

8, 9, 10. Therefore, the uncut portion due to the nick 11 does not occur. In addition, since the positions of the nicks 11 on the cutting insert 1 are determined so that the lengths of the respective cutting edge portions 12 are different, the nicks 11 of the three cutting inserts 1 are periodically separated from the work material. Does not occur.

Further, in the blade end replaceable ball end mill 20 of the present embodiment, an additional cutting insert 27 is mounted on the base end side of the tool body 21 from the position where the cutting insert 1 is mounted, but this is essential. Is not a component of Further, the shape of the additional cutting insert 27 is not limited to that shown in the figure, and can be changed as appropriate.

Next, the operation and effect of the cutting insert 1 of the present embodiment and the blade tip replaceable ball end mill 20 including the same will be described.

In the cutting insert 1 of the present embodiment, as described above, the

cutting edges

8, 9, and 10 are each provided with three cutting edges by the nicks 11 provided on the first side face 4a and the second side face 4b. It is divided into 12. And length L1, L2, L3, L4, L5 of cutting edge part 12 (12A, 12B, 12C, 12D, 12E, 12F) by planar view when the cutting insert 1 is seen from the 1st end surface 2 side. , L6 are all different from each other. With such a configuration, the following effects can be obtained. That is, in the cutting edge replaceable ball end mill 20 of the present embodiment, since the cutting insert 1 is mounted with a positive or negative axial rake, the

cutting edges

8, 9, and 10 are all work materials simultaneously. Instead of biting, the tool body 21 is bitten by the work material in order from the front end side or the base end side. This can be understood from the fact that the positions of the cutting inserts 1a, 1b, 1c in the tool body axis O direction are different as shown in FIGS. At this time, as a matter of course, the nick 11 does not bite the work material, and therefore, the cutting resistance at the time of biting temporarily disappears in the nick 11 portion. That is, the cutting resistance at the time of biting that has occurred at a constant size in the cutting edge portion 12 on the distal end side or the proximal end side of the tool body 21 temporarily disappears in the first nick 11 portion. After that, a constant cutting resistance is generated by the next cutting edge portion 12, and the cutting resistance disappears in the second nick 11 portion. The cutting resistance at the time of biting occurs. And the cutting by the rotation of the

cutting edges

8, 9, and 10 by the three cutting inserts 1 is repeated. In such a situation, if all the lengths of the cutting edge portions 12 are the same, there is a problem in that the periodicity increases and resonance tends to occur because the interval of the cutting resistance change at the time of biting is constant. . This resonance causes chatter, leading to a reduction in cutting performance and a deterioration in the surface roughness of the work material.

On the other hand, the cutting insert 1 of the present embodiment has different lengths of the cutting edge portions 12 (12A, 12B, 12C, 12D, 12E, 12F), so that the cutting resistance change at the time of biting is changed. The intervals are uneven and the periodicity is reduced. Therefore, resonance generated from periodicity can be significantly suppressed. Specifically, as shown in FIG. 6, the cutting insert 1 is mounted so as to be involved in cutting in the order of the cutting edge 8 (8b), the cutting edge 10 (10a), and the cutting edge 9 (9c). The cutting edge 8 is in the order of the

cutting edge portions

12A, 12B, 12C, the cutting edge 9 is in the order of the

cutting edge portions

12D, 12E, 12F, and the cutting edge 10 is in the order of the

cutting edge portions

12C, 12B, 12A. And bite into the work material. Therefore, in the cutting edge replaceable ball end mill 20 of the present embodiment, the periodicity of the cutting resistance at the time of biting can be reduced in the following two meanings. The first point is that there is no cutting edge portion 12 in each cutting insert 1 in which the spacing when biting is partially constant. The second point is that when three cutting inserts 1 involved in cutting are compared with each other, there is no one having the same rhythm when biting on a work material. The synergistic effect of these two factors can reduce the periodicity of the cutting resistance at the time of biting as much as possible, greatly suppressing resonance and chatter caused by it, and cutting performance and surface roughness of the work material. Can be improved.

The above effect is not limited to the shape of the cutting insert 1 of the present embodiment. That is, the present invention can be applied to a cutting insert having a shape other than a leaf shape in plan view, or a plurality of cutting edges may be formed only on the first end surface 2. Therefore, at least two

cutting edges

8 and 10 are formed at least at the intersecting ridge line between the first end face 2 and the side face 4, and the

cutting edges

8 and 10 are each at least two cutting edges by at least one nick 11. If it is divided into portions 12 and all the cutting edge portions 12 of the

cutting edges

8 and 10 have different lengths, the above effect can be exhibited.

Further, as described above, in the cutting insert 1 of the present embodiment, the

cutting edges

8 and 10 are formed on any of the end faces 2 and 3 connected to the first side face 4a. 10 is divided by a nick 11 extending straight from the first end face 2 to the second end face 3 without interruption. Therefore, the length of the cutting edge portion 12 of the cutting edge 8 and the length of the cutting edge portion 12 of the cutting edge 10 are the same. In contrast, the nick 11 does not communicate from the first end surface 2 to the second end surface 3, that is, the nick 11 extends from either the first end surface 2 or the second end surface 3 of the cutting insert 1 to the other. It is also possible to employ a configuration (not shown) that stops halfway. In this case, the length of the cutting edge portion 12 of the cutting edge 8 formed along the same side surface 4a and the length of the cutting edge portion 12 of the cutting edge 10 can be formed different from each other. Therefore, in this configuration, the effect of reducing the periodicity described above is further increased, and a further chatter suppressing effect can be obtained.

Moreover, it is preferable that the number of nicks formed on one cutting edge is two or more. This is because an increase in the number of cutting edge portions divided by nicks causes a fine change in cutting resistance when biting in one cutting edge, and the effect of suppressing resonance by disturbing periodicity is increased. Of course, there is an effect of further reducing the cutting resistance.

While typical embodiments of the present invention have been described above, the present invention can be modified in various ways, and substitutions and modifications can be made without departing from the spirit and scope of the present invention defined by the claims of the present application. Is possible.

Claims

A first end face (2), a second end face (3) facing the first end face (2), and a side face (4) connecting the first end face (2) and the second end face (3). And a cutting insert (1) provided with at least two cutting edges (8, 10) on the first end face side at the intersecting ridge line portion between the first end face (2) and the peripheral side face (4). And
The first end face side cutting edges (8, 10) are each divided into two or more cutting edge portions (12) by one or more nicks (11),
All the cutting edge portions (12) of the cutting edges (8, 10) on the first end face side have different lengths from each other,
The cutting insert (1) characterized by the above-mentioned.
2. The cutting insert (1) according to claim 1, wherein two or more of the nicks (11) are formed on each of the cutting edges (8, 10).
The cross ridge line between the second end face (3) and the side face (4) further comprises at least one second end face side cutting edge (9),
The second end face side cutting edge (9) is divided into two or more cutting edge portions (12) by one or more nicks (11);
All the cutting edge portions (12) of the cutting edge (9) on the second end face side have different lengths from each other,
Cutting insert (1) according to claim 1 or 2, characterized in that.
Two or more nicks (11) are formed on the cutting edge (9).
Cutting insert (1) according to claim 3, characterized in that.
The cutting edge part (12) of the cutting edge (9) on the second end face side is different in length from any of the cutting edge parts (12) of the cutting edge (8, 10) on the first end face side. Yes,
Cutting insert (1) according to claim 3 or 4, characterized in that.
The cutting edge portion (12) of the cutting edge (9) on the second end face side is equal in length to any of the cutting edge portions (12) of the cutting edge (8, 10) on the first end face side,
Cutting insert (1) according to claim 3 or 4, characterized in that.
When viewed from the direction facing the first end surface (2), the cutting insert (1) has a shape in which two arcuate curves are opposed to spread outward and the ends are connected to each other. is doing,
The cutting insert (1) according to any one of claims 1 to 6, characterized in that.
A tool body (21) having a rotation center axis (O) extending from the distal end side to the proximal end side, a plurality of insert seats (22) provided on the distal end side of the tool body (21), and the insert seat (22 A cutting insert that is detachably attached to the cutting edge, and a cutting edge replaceable rotary cutting tool (20),
The cutting insert is a cutting insert (1) according to any one of claims 1 to 7,
The cutting insert (1) is attached to a corresponding insert seat so as to have a positive or negative predetermined axial rake.
The plurality of insert seats (22) are mounted with the cutting inserts so that the cutting edges involved in cutting are different, and each cutting edge is simultaneously positioned at a position where it does not bite into the work material. The blade-tip-exchange-type rotary cutting tool (20) according to claim 8.