JP5294709B2 - Cutting insert and turning tool equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting insert being favorably used for shoulder cutting of 90&deg;, having a sub cutting edge with excellent strength and elongating the life of a tool in the cutting insert forming a substantially quadrangular upper face. <P>SOLUTION: This cutting insert is provided with a lower face having a substantially quadrangular shape, the upper face facing the lower face, sides, cutting edge parts formed at the upper face and the side edges, wherein the cutting edge parts have four sets of corner cutting edges located at the corner parts of the substantial quadrangle, and main cutting edges and sub cutting edges located at the both sides of the corner cutting edges. Each side face has a main flank corresponding a main cutting edge, a sub flank corresponding to a sub cutting edge, and a corner flank corresponding to a corner cutting edge. The main cutting edge is located between the corner cutting edge of the same set and the sub cutting edge of an adjacent set, and located at a higher position than the sub cutting edge of the adjacent set in the side view and inward in the top view. The corner flank has an upper corner flank located close to the corner cutting edge, and a lower corner flank located below the upper corner flank in contact with the sub flank. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a cutting insert used for a turning tool such as a face mill or an end mill.

  Conventionally, a turning tool such as a face mill or an end mill, in particular, a throw-away type turning tool to which a cutting insert can be attached and detached has been frequently used. With the recent advancement of cutting processing, further improvement in processing accuracy of cutting tools is required.

For example, Patent Document 1 discloses a cutting insert used for a cutting tool that processes a 90-degree wall surface. The cutting insert described in Patent Document 1 includes a substantially square upper surface and a lower surface, and a cutting edge portion formed on the edge portion of the upper surface, and the cutting edge portion includes a corner cutting edge and both sides of the corner cutting edge. A main cutting edge and a sub cutting edge located in The main cutting edge is positioned higher than the sub cutting edge, and the top cutting edge is formed so as not to protrude from the adjacent main cutting edge in a top view. With such a configuration, the auxiliary cutting edge not involved in cutting does not interfere with the processing wall surface of the work material, and 90-degree shoulder processing is possible.
JP 7-266120 A

  However, in the cutting insert described in Patent Document 1, the flank corresponding to the main cutting edge is composed of two surfaces having positive flank angles both above and below. And the connection point of these two upper and lower surfaces is located in a lower position than the sub cutting edge. Therefore, the secondary cutting edge adjacent to the main cutting edge has a shape positioned outward with respect to the main cutting edge through a step. That is, a corner portion is formed between the main cutting edge and the sub cutting edge adjacent to the main cutting edge.

  Therefore, the cutting insert described in Patent Document 1 has a configuration in which the cutting edge strength on the corner side of the auxiliary cutting edge is weak. Since the location is a place where a large load is applied during the cutting process among the sub-cutting blades that function as a Saray blade when arranged on the processing bottom surface side, there is a problem in that the location is easily damaged or chipped. In addition, there is a problem that chipping and chipping are likely to occur even in a corner cutting edge that is connected to the sub-cutting edge having the portion and is subjected to a large load during the cutting process.

  The present invention has been made to solve such problems of the prior art, and is a cutting insert having a substantially rectangular upper surface, which is preferably used for shoulder processing of 90 degrees, An object of the present invention is to provide a cutting insert having a long tool life having a cutting edge portion exhibiting excellent cutting edge strength while suppressing interference.

In order to solve the above problems, a cutting insert according to the present invention includes a substantially rectangular lower surface, an upper surface facing the lower surface, a side surface, and a cutting edge portion formed on the upper surface and the edge portion. It is a cutting insert, and the cutting edge portion has four sets of a corner cutting edge located at the corner of the substantially square shape, and a main cutting edge and a sub cutting edge located on both sides of the corner cutting edge, respectively. The side surface includes a main clearance surface corresponding to the main cutting edge, a secondary clearance surface corresponding to the secondary cutting edge, and a corner clearance surface corresponding to the corner cutting edge, The blade is located between the corner cutting blade of the same set and the sub cutting blade of the adjacent set, and is higher than the adjacent cutting blade of the adjacent set in a side view and in a top view. Located on the inside, the corner flank is a flank on the corner adjacent to the corner cutting edge Has a a corner under flank in contact with the secondary clearance surface with located below the corner on the flank, relief angle of the corner on the flank, a 0 ° or negative, and, It decreases as it goes to the sub flank from the main flank .

  The cutting tool according to the present invention is formed by attaching the above-described cutting insert to a holder.

  A cutting method of a work material according to the present invention is a method of cutting a work material, wherein at least one of the work material and the above-described rolling tool is rotated to cut the work material. A step of bringing the cutting blade portion of the insert close, a step of bringing the cutting blade portion into contact with the surface of the work material and cutting the work material, and a step of separating the cutting blade portion from the work material. , Provided.

  According to the cutting insert of the present invention, it is possible to provide a cutting insert that has a high cutting edge strength, suppresses chipping and chipping of the cutting edge, and is suitable for shoulder processing with a long tool life of 90 degrees.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 to 9 show an embodiment of the present invention. FIG. 1 is an overall perspective view of a cutting insert (hereinafter abbreviated as an insert) 1 according to a first embodiment of the present invention, and FIG. They are (a) top view of the insert 1, and (b) side view. FIG. 3 is an enlarged view of a main part of FIG. 4 is an overall perspective view of the insert 21 according to the second embodiment of the present invention, and FIG. 5 is an (a) top view and (b) a side view of the insert 21. FIG. 6 is an enlarged view of a main part of FIG. Further, FIG. 7 is an explanatory diagram for explaining the arrangement of the cutting blade portion in a state where the insert 1 is attached to the holder 10. FIG. 8 is an overall perspective view of the rolling tool equipped with the insert 1 (simplified view) according to the first embodiment of the present invention. Further, FIG. 9 is a cross-sectional view taken along line AA in FIG.

  Hereinafter, the insert 1 according to the first embodiment will be described with reference to FIGS. 1 to 3.

  In FIG. 1, an insert 1 according to the first embodiment includes a substantially rectangular lower surface 2, an upper surface 3 facing the lower surface 2, a side surface 4, and a cutting edge portion 5 formed at the edge of the upper surface 3. And. The upper surface 3 is a surface that functions as a rake surface.

  The cutting edge portion 5 includes a corner cutting edge 51, and a main cutting edge 52 and a sub cutting edge 53 that are respectively located on both sides of the corner cutting edge 51. The insert 1 according to the present embodiment includes four sets of cutting edge portions 5.

  The corner cutting edge 51 is a cutting edge located at a substantially rectangular corner. As shown in FIG. 2A, the corner cutting edge 51 is located between the main cutting edge 52 and the auxiliary cutting edge 53. In the present embodiment, the main cutting edge 52 is connected to the corresponding corner cutting edge 51 (the same set of corner cutting edges 51) at one end. On the other hand, at the other end, the main cutting edge 52 is connected to an adjacent set of auxiliary cutting edges 53 '(hereinafter referred to as an adjacent set of auxiliary cutting edges 53'). That is, the main cutting edge 52 is positioned between the same set of corner cutting edges 51 and the adjacent set of auxiliary cutting edges 53 ′ located on the same side as the corner cutting edges 51.

  The main cutting edge 52 is a cutting edge part that cuts the machining wall surface during shoulder machining of 90 degrees. On the other hand, the auxiliary cutting edge 53 is a cutting edge portion that cuts the machining bottom surface during shoulder machining of 90 degrees. That is, the auxiliary cutting edge 53 is a Saray blade.

  The side surface 4 has a main flank 42 corresponding to the main cutting edge 52 and a sub flank 43 corresponding to the sub cutting edge 53. Here, the flank corresponding to the cutting edge refers to a side surface portion that substantially functions as a flank with respect to the cutting edge.

  In the present embodiment, the main cutting edge 52 is positioned higher than the sub cutting edge 53. Further, as shown in FIGS. 2A and 3, the main cutting edge 52 is located inward of the auxiliary cutting edge 53 in a top view.

  The main flank 42 has an upper flank 42A close to the main cutting edge 52, and a lower flank 42B positioned below the upper flank 42A. That is, the insert 1 of the present embodiment has a two-surface configuration in which flank surfaces corresponding to the main cutting edge 52 are arranged side by side. In the insert 1 of this embodiment, the flank corresponding to the auxiliary cutting edge 53 is composed of one surface.

  Further, the side surface 4 further has a corner relief surface 41. The corner flank 41 corresponds to the corner cutting edge 51 and is located between the main flank 42 and the auxiliary flank 43. And in this embodiment, this corner flank 41 is comprised by two surfaces arrange | positioned up and down similarly to the main flank 42, as shown in FIG.1 and FIG.2 (b). .

  Specifically, the corner flank 41 has an upper corner flank 41A positioned close to the corner cutting edge 51 and a lower corner flank 41B positioned below the upper corner flank 41A. doing. As shown in FIGS. 1 and 2B, the corner lower flank 41 </ b> B is in contact with the auxiliary flank 43.

  With such a configuration, it is possible to improve the cutting edge strength of the corner cutting edge 51 while suppressing interference between the cutting edge and the work material. That is, at the time of cutting, the main cutting edge 52 that is not involved in the cutting, which is disposed on the machining bottom surface, and the auxiliary cutting edge 53 that is not involved in the cutting, which is disposed on the machining wall surface, are both Further, it can be arranged so as not to interfere with the opposite processing bottom surface and processing wall surface. In addition, it is possible to improve the cutting edge strength of the corner cutting edge 51 to which a large load is applied during cutting. Therefore, it becomes an insert with excellent finished surface accuracy and a long tool life.

  In the insert 1 of the present embodiment, the clearance angle of the upper corner flank 41 </ b> A decreases from the corresponding main flank 42 toward the sub flank 43.

  Further, in the insert 1 of the present embodiment, the clearance angle of the corner flank 41A is 0 degree or negative, and the absolute value thereof increases from the corresponding main flank 42 to the sub flank 43. . In the present embodiment, the clearance angle of the corner flank 41 </ b> A increases as the absolute value increases from the corresponding main flank 42 to the sub flank 43.

  In the insert 1 of the present embodiment, the clearance angle of the upper clearance surface 42A is 0 degree or negative. On the other hand, the clearance angle of the lower clearance surface 42B and the clearance angle of the auxiliary clearance surface 43 are positive. Specifically, the upper clearance surface 42A of the insert 1 of the present embodiment has a negative clearance angle.

  The lower flank 42B of the insert 1 of the present embodiment is in contact with the auxiliary flank 43 'of the adjacent secondary cutting edge 53' (the adjacent secondary cutting edge 53 ') of the corresponding main cutting edge 52. ing. In other words, as shown in FIG. 8, in the cross-sectional view passing through the end portion of the adjacent secondary cutting edge 53 ′ and perpendicular to the adjacent secondary cutting edge 53 ′, When viewed from the cutting edge 53 ′ side toward the corner cutting edge 51, the upper end portion of the auxiliary flank 43 ′ corresponding to the adjacent auxiliary cutting edge 53 ′ is on the virtual extension line X of the lower flank 42B. To position. That is, the sub-flank 43 'is in contact with the lower flank 42B (adjacent lower flank 42B) located on the back side without a step portion in the cross-sectional view. That is, the secondary flank 43 'has a shape that does not protrude outward with respect to the lower flank 42B. Here, the outward means an outward in a direction substantially perpendicular to the thickness direction of the insert 1.

  With such a configuration, 90-degree shoulder machining can be performed using the entire cutting edge length of the main cutting edge, and the end of the adjacent cutting edge 53 'on the main cutting edge 52 side. The cutting edge strength can be improved. Therefore, when the location is used as a bottom blade, that is, a Saray blade, it is possible to suppress the sub-cutting blade 53 from being chipped or chipped. Therefore, 90-degree shoulder machining is an insert with a long tool life that allows machining using the entire cutting edge length of the main cutting edge.

  In the present embodiment, as shown in FIGS. 1 and 2B, the upper flank 42A, the lower flank 42B, and the auxiliary flank 43 intersect the main flank 42, that is, The three surfaces are formed so as to contact at one point (T). With such a configuration, the effect of improving the strength of the end of the secondary cutting edge 53 'on the main cutting edge 52 side is further enhanced. In the present embodiment, the upper flank 42A is a curved surface, and the lower flank 42B is a flat surface. Further, the auxiliary flank 43 'is also a flat surface.

  FIG. 3 is an enlarged view of one corner of FIG. As shown in FIG. 3, the insert 1 of the present embodiment is formed such that, on the upper surface, the auxiliary cutting edge 53 ′ is positioned inward from the outer peripheral surface of the insert 1 corresponding to the main cutting edge 52. That is, in the present embodiment, the main flank 42 corresponding to the main cutting edge 52 has a positive flank on the lower side and a negative flank on the upper side. Therefore, in the top view, the outer peripheral surface of the insert portion corresponding to the main cutting edge 52 corresponds to the connecting portion 6 (intersection portion 6) between the upper upper clearance surface 42A and the lower lower clearance surface 42B. Therefore, in the present embodiment, the auxiliary cutting edge 53 ′ is provided to be inclined inward from the connecting portion 6 (intersection portion 6) between the upper flank 42 </ b> A and the lower flank 42 </ b> B.

  With such a cutting edge arrangement, it is possible to further suppress interference of the auxiliary cutting edge 53 ′ arranged on the processing wall side with the work material when performing shoulder machining of 90 degrees. Therefore, the processing wall surface can be processed using the entire length of the main cutting edge 52, and the finished surface accuracy can be improved. Therefore, the cutting depth is not limited, the machining efficiency is excellent, and cutting with high machining accuracy can be performed.

  Further, as shown in FIGS. 1 and 2 (b), the auxiliary flank 43 is configured in the same plane as the lower flank 42B. That is, in the present embodiment, the auxiliary flank 43 and the lower flank 42B are configured by the same plane.

  With such a configuration, the end portion on the adjacent main cutting edge 52 side of the auxiliary cutting edge 53 ′ is positioned on the same plane as the lower clearance surface 42 </ b> B of the adjacent main clearance surface 42. Therefore, the cutting edge strength at the end of the sub cutting edge 53 'on the side of the adjacent main cutting edge 52 is further increased. In addition, when attached to the drill with a positive axial rake, the same clearance angle can be ensured from the main cutting edge 52 to the adjacent auxiliary cutting edge 53 ′ on the lower surface side of the insert 1. As a result, the cutting edge strength of both the main cutting edge 52 and the auxiliary cutting edge 53 can be secured stably. In addition, it is preferable from the viewpoint of manufacturing that the auxiliary flank 43 and the lower flank 42B are configured in the same plane. That is, with such a configuration, the shape is simple and the processing cost can be reduced.

  Further, as shown in FIG. 2 (b), in a side view, the lower edge of the upper flank 42A is adjacent to the adjacent cutting edge 53 'at the end of the adjacent cutting edge 53' side. Located at the same height. Further, the lower edge of the upper flank 42A is positioned on substantially the same straight line as the adjacent pair of auxiliary cutting edges 53 '. With such a configuration, it is possible to improve the strength of the cutting edge at the end of the auxiliary cutting edge 53 ′ adjacent to the main cutting edge 52.

  Furthermore, as shown in FIG. 2B, the auxiliary cutting edge 53 is provided so as to be substantially parallel to the lower surface. With such a configuration, a sufficient contact area between the auxiliary cutting edge 53 and the work material can be secured. That is, it is possible to secure a large cutting edge length that substantially functions of the auxiliary cutting edge 53. Therefore, it becomes an insert with high processing efficiency.

  In the present embodiment, as shown in FIG. 2B, the secondary cutting edge 53 is substantially parallel to the lower surface, and as described above, the upper flank 42A is collinear with the secondary cutting edge '. The lower edge is located. Therefore, in this embodiment, both the sub cutting edge 53 and the lower end of the upper flank 42A are arranged so as to be substantially parallel to the lower surface.

  Moreover, as shown in FIG. 1 and FIG. 2B, the main cutting edge 52 has an inclined region 521 that is inclined so as to become higher as it approaches the corresponding corner cutting edge 51. Thereby, cutting resistance can be reduced without providing a large axial rake and attaching it to the holder 10.

  The main cutting edge 52 of the present embodiment further has a flat area 522 that is located on the corresponding corner cutting edge 51 side with respect to the inclined area 521 and is substantially parallel to the lower surface. With such a configuration, the strength of the cutting edge of the corner cutting edge 51 and the main cutting edge 52 that are subjected to a large load during the cutting process is improved. Therefore, the effect of suppressing chipping and chipping of the cutting edge during cutting is enhanced.

  Next, the insert 21 according to the second embodiment of the present invention will be described with reference to FIGS. 4 to 6. In addition, about the structure similar to FIG. 1 thru | or FIG. 3, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  Unlike the first embodiment, the insert 21 according to the second embodiment corresponds to the lower flank 42B-1 of the main flank 42 corresponding to the main cutting edge 52 and the sub-cutting blade 53 'of the adjacent set. The auxiliary flank 43′-1 is constituted by different surfaces. Thus, even when the lower flank 42B-1 and the sub flank 43'-1 are composed of two different surfaces, as shown in FIGS. 5 and 6B, the lower flank 42B -1 is formed so as to be in contact with the auxiliary flank 43'-1.

  Also in this embodiment, as in the first embodiment, the lower flank 42B-1, the sub flank 43'-1, and the upper flank 42A are formed so as to contact each other.

  Furthermore, the insert 21 according to the second embodiment is different from the first embodiment in the shape of the cutting edge of the auxiliary cutting edge 53. That is, in the insert 21 according to the second embodiment, the auxiliary cutting edge 53 is formed so as to form an arc shape in a top view as shown in FIGS. Thus, the sub cutting blade 53 that functions as a Saray blade has an arc shape, so that it is possible to suppress a decrease in processing accuracy due to a very small attachment error when attached to the holder 10. Therefore, 90-degree shoulder processing with high processing accuracy is possible. In addition, the arcuate cutting edge can improve the cutting edge strength.

  Also in this embodiment, as shown in FIG. 6, the top cutting edge 53 ′ is located inward of the virtual extension line of the outer peripheral surface of the insert 21 corresponding to the main cutting edge 52 in a top view. To do. By adopting such a cutting edge arrangement, as described above, shoulder processing of 90 degrees can be performed with high processing accuracy without limitation of the cutting depth.

  Next, a turning tool 11 according to an embodiment of the present invention will be described with reference to FIGS. 7 and 8, the same components as those in FIGS. 1 to 6 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 7, the cutting tool 11 according to the present embodiment has the above-described insert 1 attached to the tip of a holder 10. In FIG. 7, the insert 1 is shown in a simplified manner. The holder 10 constituting the rolling tool 11 according to the present embodiment is formed with four insert pockets 12 provided at the distal end portion thereof so as to open at the distal end surface and the outer peripheral surface of the holder 10. And insert 1 is attached to these four insert pockets 12, and it is used as a turning tool. That is, in this embodiment, the form which attached four inserts is illustrated.

  Hereinafter, a state in which the insert 1 having the above-described configuration is attached to the holder 10 will be described. FIG. 7 is a schematic explanatory view of the insert 1 showing a state where it is attached to the holder 10. Note that the holder 10 and the insert pocket 12 are omitted.

  In this embodiment, as shown in FIG. 7, the insert 1 is attached to the holder 10 so that the axial rake is positive and the radial rake is negative. By adopting the arrangement of the insert 1 in this way, the following cutting edge arrangement can be realized.

  As shown in FIG. 7, in the shoulder processing at 90 degrees, first, the auxiliary cutting edge 53 for cutting the processing bottom surface side is arranged on the holder 10 so that at least a part protrudes from the tip surface of the holder 10. At this time, the main cutting edge 52 that is not involved in the cutting disposed on the processing bottom surface side is positioned so as not to contact the processing bottom surface of the work material.

  And the main cutting edge 52 which cuts a process wall surface is arrange | positioned so that at least one part may protrude from the outer peripheral surface of the holder 10. FIG. At this time, the sub-cutting blade 53 that is not involved in the cutting and is disposed on the outer peripheral surface side of the holder 10 is disposed so as not to contact the processing wall surface of the work material.

  With the rolling tool 11 having such a cutting edge arrangement, it is possible to suppress damage to the processing surface due to the interference of the cutting edge in 90-degree shoulder processing. Therefore, 90-degree shoulder processing can be performed with high processing accuracy, and chipping and chipping of the cutting edge can be suppressed. Therefore, the tool life can be improved and machining with high machining accuracy can be stably performed over a long period of time.

  Finally, a cutting method for a work material according to an embodiment of the present invention will be described.

  The cutting method of the work material by this embodiment comprises the following three processes.

  First, a step (proximity step) of rotating at least one of the work material and the above-described rolling tool to bring the cutting edge portion of the cutting insert close to the work material is provided. In the proximity step, either the cutting tool or the work material according to the embodiment of the present invention may be rotated, or both may be rotated. Moreover, the cutting tool and work material which concern on one Embodiment of this invention should just approach relatively, for example, a work material may be made to approach the cutting blade of a cutting tool.

  And it has the process (cutting process) which makes a cutting blade part contact the surface of a work material, and cuts a work material. In the cutting step, for example, the cutting process is continued by bringing the cutting blade of the cutting tool into contact with a different part of the work material while maintaining a state where at least one of the cutting tool and the work material is rotated. It is preferable to carry out.

  Furthermore, it comprises a step of separating the cutting edge portion from the work material (separation step). In the separation step, similarly to the proximity step, the cutting tool and the work material according to an embodiment of the present invention may be relatively distant from each other, for example, the work material may be kept away from the cutting blade of the cutting tool. May be.

  Such a cutting method of the work material enables cutting with high processing efficiency and high processing surface accuracy. Therefore, it is possible to obtain a workpiece that exhibits excellent finished surface accuracy at low cost.

  As mentioned above, although embodiment of this invention was illustrated, this invention is not limited to embodiment, It cannot be overemphasized that it can be made arbitrary, unless it deviates from the objective of invention.

  For example, in the above-described embodiment, the form in which the insert is disposed at substantially the same position in the axial direction of the holder is illustrated. That is, an example in which four inserts are radially arranged at the distal end portion of the holder as viewed from the distal end is illustrated. However, the present invention is not limited to this, and a configuration in which only one insert is arranged may be used.

  Furthermore, although the end mill has been exemplified in the above-described embodiment, the present invention is not limited to this, and can be suitably used in other rolling tools such as a face mill.

  As mentioned above, although embodiment of this invention was illustrated, this invention is not limited to embodiment, It cannot be overemphasized that it can be made arbitrary, unless it deviates from the objective of invention.

FIG. 1 is an overall perspective view of an insert 1 according to a first embodiment of the present invention. 2A is a top view of the insert 1 and FIG. 2B is a side view thereof. FIG. 3 is an enlarged view of a main part of FIG. FIG. 4 is an overall perspective view of the insert 21 according to the second embodiment of the present invention. 5A is a top view of the insert 21 and FIG. 5B is a side view thereof. FIG. 6 is an enlarged view of a main part of FIG. FIG. 7 is an explanatory diagram for explaining the arrangement of the cutting blade portion in a state where the insert 1 is attached to the holder 10. FIG. 8 is an overall perspective view of the turning tool to which the insert 1 is mounted. FIG. 9 is a cross-sectional view taken along the line AA in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cutting insert by 1st Embodiment 2 Lower surface 3 Upper surface 4 Side surface (flank)
41 Corner flank 41A Corner flank 41B Corner flank 42 Main flank 42A Upper flank 42B Lower flank 43 Sub flank 5 Cutting edge 51 Corner cutting edge 52 Main cutting edge 53 Sub cutting edge 6 Connection part ( Intersection)
10 Holder 11 Turning tool 12 Insert pocket

Claims (8)

A cutting insert comprising a substantially rectangular lower surface, an upper surface facing the lower surface, a side surface, and a cutting edge portion formed on the upper surface and the edge portion,
The cutting edge portion has four sets of corner cutting edges located at the corners of the substantially square shape, and main cutting edges and auxiliary cutting edges located on both sides of the corner cutting edges,
The side surface has a main flank corresponding to the main cutting edge, a sub flank corresponding to the sub cutting edge, and a corner flank corresponding to the corner cutting edge,
The main cutting edge is located between the corner cutting edge of the same set and the secondary cutting edge of the adjacent set, and is higher than the adjacent cutting edge in a side view, and Located inward in top view,
The corner flank has a corner flank close to the corner cutting edge, and a corner flank located below the flank above the corner and in contact with the auxiliary flank ,
The cutting insert according to claim 1, wherein a clearance angle of the flank on the corner is 0 degree or negative, and decreases from the main flank to the sub flank .   The main flank has an upper flank close to the main cutting edge and in contact with the upper flank and a lower flank located below the upper flank and in contact with the lower flank. The cutting insert according to claim 1, wherein: In side view, the lower edge of the upper flank, claim 2, wherein the minor cutting edge side end portion of the pair of adjacent, characterized in that located on the minor cutting edge substantially the same height of the set of next Cutting insert as described in. 4. The cutting insert according to claim 3 , wherein a lower edge of the upper flank has a parallel region located on the same straight line as the adjacent pair of auxiliary cutting edges. 5. The minor cutting edge is the cutting insert according to any one of claims 1 to 4, wherein the is a bottom substantially parallel. The cutting insert according to any one of claims 1 to 5 , wherein the main cutting edge has an inclined region that is inclined so as to become higher as it approaches the corresponding corner cutting edge. A cutting tool comprising the cutting insert according to any one of claims 1 to 6 attached to a holder. A method of cutting a work material,
Rotating at least one of the work material and the rolling tool according to claim 7 to bring the cutting edge portion of the cutting insert close to the work material;
Cutting the work material by bringing the cutting edge portion into contact with the surface of the work material; and
And a step of separating the cutting edge portion from the work material.