JP2015100901A - Cutting insert, cutting tool and manufacturing method of workpiece to be cut - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in which: increasing an area of a restraining surface is required to fix a cutting insert to a holder stably, however, when the area of the restraining surface is increased, durability of a cutting blade has become a problem.SOLUTION: A cutting insert comprises: a substantially polygonal upper surface; a lower surface; side surfaces located between the upper and lower surfaces; cutting blades formed at intersection line parts of the upper surface and the side surfaces; and a through hole formed from the center of the upper surface toward the center of the lower surface. The cutting blades comprise first cutting blades formed at positions corresponding to the side parts of the upper surface and second cutting blades formed at positions corresponding to the corner parts of the upper surface. The side surfaces are positioned along the first cutting blades and comprise: main clearance surfaces inclining from the upper surface side toward the lower surface side so as to approach the through hole; step parts located below the main clearance surfaces; and flat restraining surfaces located between the lower parts of the step parts and the lower surface. A clearance angle of the main clearance surface becomes larger as approaching the second cutting blade.

Description

  The present invention relates to a cutting insert, a cutting tool, and a method for manufacturing a workpiece.

  As a cutting tool used for milling a workpiece such as metal, a tool described in Patent Document 1 is known. The cutting element (cutting insert) in the tool described in Patent Document 1 includes a plurality of cutting edges (cutting blades) at the intersection line between the substantially polygonal first surface (upper surface) and the outer surface. Further, the cutting insert described in Patent Document 1 has a flank formed along the cutting edge on the outer surface and a planar seating surface (restraint surface) connected to the flank through a step. An opening (through hole) is formed from the upper surface to the lower surface. The constraining surface comes into contact with the base of the tool body (holder), and the cutting insert is attached to the holder via a fixing screw inserted into the through hole.

  When performing cutting such as milling, a force that rotates about the axis of the fixing screw is applied to the cutting insert from the work material. Since the constraining surface formed on the side surface of the cutting insert is in contact with the base of the holder, the cutting insert is suppressed from rotating.

Special table 2007-515303 gazette

  In recent years, there has been a demand for good machining even when a greater force is applied to the cutting insert. The area of the constraining surface can be increased by reducing the flank and forming the constraining surface in a region close to the cutting edge. However, when the constraining surface is formed in this way, the durability of the cutting blade is lowered. In particular, since the volume of the chips increases as the depth of cut increases from the upper edge of the cutting edge, the durability of the cutting edge in the above region becomes a problem.

  The present invention has been made in view of the above problems, and it is possible to provide a cutting insert, a cutting tool, and a cut product that can ensure a sufficient area of a restraint surface while suppressing an excessive decrease in the durability of the cutting blade. It is to provide a manufacturing method.

  A cutting insert according to an aspect of the present invention includes a substantially polygonal upper surface, a lower surface, a side surface located between the upper surface and the lower surface, and a cutting line formed at the intersection of the upper surface and the side surface. A blade and a through-hole formed from the center of the upper surface toward the center of the lower surface. The cutting edge includes a first cutting edge formed at a position corresponding to a side portion of the upper surface, and a second cutting edge formed at a position corresponding to a corner portion of the upper surface, The first cutting edge is positioned outward from an imaginary straight line connecting the respective boundaries between one cutting edge and the pair of second cutting edges adjacent to the first cutting edge. The side surface is located along the first cutting edge, and has a main flank surface that inclines so as to approach the through hole from the upper surface side toward the lower surface side, and below the main flank surface And a flat constraining surface located below the stepped portion. And the clearance angle of the said main flank becomes large as it approaches the said 2nd cutting blade.

  In the cutting insert of the above aspect, the cutting blade includes a first cutting blade formed at a position corresponding to the side portion of the upper surface, and a second cutting blade formed at a position corresponding to the corner portion of the upper surface. Have. The side surface has a main flank located along the first cutting edge, a step portion located below the main flank, and a flat constraining surface located below the step portion. And the clearance angle of the main flank located above a flat restraint surface becomes large as it approaches the 2nd cutting edge.

  By forming the clearance angle of the main flank as described above, it is possible to secure a large area of the constraining surface located below the portion of the first cutting edge close to the second cutting edge. Therefore, the area of the region located below the portion near the second cutting edge in the constraining surface can be increased, and the constraining surface can be brought close to the first cutting blade in this region. Thus, since the area in the area | region away from the through-hole among restraint surfaces can be enlarged, it is suppressed that a cutting insert rotates, and a cutting insert can be stably fixed to a holder.

  On the other hand, since the clearance angle of the first flank in the portion away from the second cutting edge is relatively small, the constraining surface located below the portion of the first cutting blade far from the second cutting edge Can be suppressed from approaching the cutting blade excessively. Therefore, the durability of the first cutting edge can be kept high in a portion of the first cutting edge away from the second cutting edge.

It is a perspective view which shows the cutting insert of one Embodiment of this invention. It is a top view of the cutting insert shown in FIG. It is a side view from the A direction in the cutting insert shown in FIG. It is sectional drawing of the A1-A1 cross section in the cutting insert shown in FIG. It is sectional drawing of the A2-A2 cross section in the cutting insert shown in FIG. It is sectional drawing of the A3-A3 cross section in the cutting insert shown in FIG. It is sectional drawing of A4-A4 cross section in the cutting insert shown in FIG. It is sectional drawing of A5-A5 cross section in the cutting insert shown in FIG. It is sectional drawing of A6-A6 cross section in the cutting insert shown in FIG. It is a perspective view which shows the cutting tool of one Embodiment of this invention. It is a side view of the cutting tool shown in FIG. It is a perspective view which shows 1 process of the manufacturing method of the cut workpiece of one Embodiment of this invention. It is a perspective view which shows 1 process of the manufacturing method of the cut workpiece of one Embodiment of this invention. It is a perspective view which shows 1 process of the manufacturing method of the cut workpiece of one Embodiment of this invention.

<Cutting insert>
Hereinafter, the cutting insert of one embodiment is explained in detail using a drawing. However, in the drawings referred to below, for convenience of explanation, among the constituent members of the embodiment, only the main members necessary for explaining the present invention are shown in a simplified manner. Therefore, the cutting insert of the present invention may include any component not shown in the drawings to which the present specification refers. Moreover, the dimension of the member in each figure does not represent the dimension of an actual structural member, the dimension ratio of each member, etc. faithfully.

The cutting insert 1 (hereinafter also simply referred to as the insert 1) of the present embodiment includes an upper surface 3, a lower surface 5, a side surface 7, a cutting edge 9, and a through hole 11. Examples of the material of the insert 1 include cemented carbide or cermet. As a composition of the cemented carbide, for example,
WC-Co produced by adding cobalt (Co) powder to tungsten carbide (WC) and sintering, WC-TiC-Co with titanium carbide (TiC) added to WC-Co, or WC-TiC-Co There is WC—TiC—TaC—Co in which tantalum carbide (TaC) is added. The cermet is a sintered composite material in which a metal is combined with a ceramic component, and specifically includes a titanium compound mainly composed of titanium carbide (TiC) or titanium nitride (TiN).

The surface of the insert 1 may be coated with a film using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method. Examples of the composition of the coating include titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), and alumina (Al ₂ O ₃ ).

  The upper surface 3 has a substantially polygonal shape, and has a substantially rectangular shape in this embodiment. Here, the substantially polygonal shape does not mean strictly a polygonal shape. For example, the corner portions on the upper surface 3 in the present embodiment are not strict corners, but are rounded. Further, the side portions positioned so as to connect the adjacent corner portions are not strictly linear but have a shape protruding slightly toward the outside.

  The lower surface 5 is a surface located on the side opposite to the upper surface 3 and functions as a seating surface for the insert pocket when the insert 1 is attached to the holder. The lower surface 5 in the present embodiment has a substantially polygonal shape, specifically a substantially rectangular shape, like the upper surface 3. At this time, the lower surface 5 is configured to be slightly smaller than the upper surface 3. Further, the lower surface 5 in the present embodiment has a flat surface shape.

  The shapes of the upper surface 3 and the lower surface 5 are not limited to the above-described form. In the insert 1 of the present embodiment, the shape of the upper surface 3 when the upper surface is raised is substantially square. For example, the shape of the upper surface 3 when the upper surface is raised is a polygonal shape such as a triangle, pentagon, hexagon or octagon. There may be.

  The side surface 7 is located between the upper surface 3 and the lower surface 5 and is connected to the upper surface 3 and the lower surface 5. As described above, since the lower surface 5 is slightly smaller than the upper surface 3, the region connected to the upper surface 3 on the side surface 7 is smaller than the region connected to the lower surface 5 on the side surface 7 when viewed in plan. Located on the outside.

  The maximum width when the top surface 3 of the insert 1 of the present embodiment is viewed from above is 6 to 20 mm. The height from the lower surface 5 to the upper surface 3 is 3 to 7 mm. Here, the height from the lower surface 5 to the upper surface 3 means a width in a direction parallel to the through hole 11 between the upper end of the upper surface 3 and the lower end of the lower surface 5.

  The cutting edge 9 is formed at the intersection of the upper surface 3 and the side surface 7. The cutting edge 9 is used for cutting a work material in cutting. In the insert 1 of the present embodiment, the cutting edge 9 is formed on the entire intersecting portion of the upper surface 3 and the side surface 7, but is not particularly limited to such a form. There may be a portion where the cutting edge 9 is not formed in a part of the intersection line between the upper surface 3 and the side surface 7.

  Moreover, the intersection line part of the upper surface 3 and the side surface 7 is not a strict line shape by two surfaces intersecting. If the intersection line is sharp at an acute angle, the durability of the cutting edge 9 is reduced. Therefore, the portion where the upper surface 3 and the side surface 7 intersect may be subjected to a so-called honing process in which the curved surface is slightly formed.

  The insert 1 of the present embodiment has a through hole 11 formed from the center of the upper surface 3 toward the center of the lower surface 5. The through hole 11 is provided to insert a screw when the insert 1 is fixed to the holder of the cutting tool with a screw. The lower surface 5 in the present embodiment is a flat surface, and the direction of the central axis X of the through hole 11, in other words, the through direction is orthogonal to the lower surface 5.

  The cutting edge 9 has a plurality of first cutting edges 13 and a plurality of second cutting edges 15. The plurality of first cutting edges 13 are respectively formed at positions corresponding to the side portions of the upper surface 3. That is, the insert 1 of this embodiment has four first cutting edges 13. The plurality of second cutting edges 15 are respectively formed at positions corresponding to the corners of the upper surface 3 and are so-called corner cutting edges. That is, the insert 1 of the present embodiment has four second cutting edges 15.

  Since the corners on the upper surface 3 in the present embodiment have rounded shapes, the plurality of second cutting edges 15 each have an arc shape protruding outward. Moreover, the side part in the upper surface 3 in this embodiment becomes a shape which protrudes slightly toward the outer side. Specifically, when viewed from above, it is constituted by two straight line portions and a curved line portion connecting these straight line portions.

  Therefore, the first cutting edge 13 in the insert 1 of the present embodiment is not configured by one straight line portion, and when viewed from the top, the two straight line portions and a curved portion that connects these straight line portions. And is composed of. In the insert 1 of this embodiment, one of these two straight portions functions as a so-called wiper blade, and the other functions as a so-called main cutting blade. Moreover, the 1st cutting blade 13 is comprised by the two linear parts and the curve part which connects these linear parts, also when it sees from a side view. However, the curved portion when viewed from the top and the curved portion when viewed from the side do not coincide with each other and are formed at different locations.

  A portion of the first cutting edge 13 connected to the second cutting edge 15 has a linear shape when viewed from above, and the second cutting edge 15 has an arc shape. Therefore, the boundary between the first cutting edge 13 and the second cutting edge 15 is determined by the boundary between the linear portion and the arc-shaped portion in the cutting blade 9.

  The upper surface 3 has a land surface 17 and an inclined surface 19 (rake face 19). The land surface 17 is provided along the cutting edge 9. That is, the land surface 17 is located on the outer peripheral edge of the upper surface 3 and is connected to the cutting edge 9. The land surface 17 is an inclined surface that is substantially parallel to the lower surface 5 or decreases in height toward the center. There is no problem even if the land surface 17 is an inclined surface whose height increases toward the center.

  Note that “substantially parallel” does not mean that they are strictly parallel, but may mean that they may have a deviation of about ± 1 °. If it is difficult to evaluate whether the lower surface 5 is not flat but parallel to the lower surface 5, it may be compared with the central axis X instead of the lower surface 5. That is, the land surface 17 may be evaluated based on whether or not it is perpendicular to the central axis X.

  The cutting edge 9 is formed at the intersection of the land surface 17 and the side surface 7. The land surface 17 is provided to increase the strength of the cutting edge 9. When the land surface 17 is not provided, the cutting edge 9 is formed at the intersection of the rake surface 19 and the side surface 7. The rake face 19 surrounded by the land face 17 and located inside the land face 17 is an inclined face whose height from the lower face 5 becomes lower toward the center. The inclination angle of the rake face 19 is larger than the inclination angle of the land face 17.

That is, the strength of the cutting edge 9 can be increased by having the land surface 17 having an inclination angle smaller than the inclination angle of the rake face 19. The inclination angles of the rake face 19 and the land face 17 described above mean an angle formed by a straight line orthogonal to the central axis in a cross section including the central axis X and the target surface. The width of the land surface 17 indicated by the distance between the outer periphery of the upper surface 3 and the outer periphery of the rake face 19 is appropriately set according to the cutting conditions, but is set in the range of 0.01 to 1 mm, for example.

  The rake face 19 is located inside the land face 17. The rake face 19 plays a role of scooping off the chips cut by the cutting edge 9. Therefore, chips of the work material flow on the surface of the rake face 19. The rake face 19 is inclined so that the height from the lower face 5 decreases as the distance from the land face 17 increases, in order to scoop off chips well. In other words, in the insert 1 of the present embodiment, the rake surface 19 is an inclined surface that is inclined so as to approach the lower surface 5 as it approaches the through hole 11.

  Further, the upper surface 3 of the insert 1 of the present embodiment has a rising surface 29 positioned inside the rake surface 19 and a flat surface 31 positioned inside the rising surface 29. The rising surface 29 is inclined so that the height from the lower surface 5 increases as the distance from the rake surface 19 increases.

  Note that “located on the inner side” in the rake face 19, the rising face 29, and the flat face 31 means that the rake face 19, the rising face 29, and the flat face 31 are located closer to the central axis X. If the lower surface 5 is not a flat surface and it is difficult to evaluate the height from the lower surface 5, the height from the virtual plane orthogonal to the central axis X is used instead of the height from the lower surface 5. You may evaluate by.

  The side surface 7 has a main flank 21, a corner flank 23, and a restraint surface 25. The main flank 21 is a part of the side surface 7 on the side of the upper surface 3, and is a portion provided at a position along the first cutting edge 13. The corner flank 23 is a part of the side surface 7 on the side of the upper surface 3 and is a portion provided at a position along the second cutting edge 15 (corner cutting edge). The restraining surface 25 is a part of the side surface 7 on the side of the lower surface 5 and is a portion located between the main clearance surface 21 and the lower surface 5. In FIG. 3, the area of the constraining surface 25 is illustrated with diagonal lines in order to facilitate visual understanding.

  The main flank 21, the corner flank 23, and the restraint surface 25 are inclined so as to approach the through hole 11 from the upper surface 3 toward the lower surface 5. In consideration of the degree of freedom of axial rake when the insert 1 is attached to the holder, the constraining surface 25 is preferably inclined so as to approach the through hole 11 from the upper surface 3 side toward the lower surface 5 side. .

  The restraint surface 25 is a surface used for fixing the insert 1 by contacting the restraint side surface of the holder when the insert 1 is mounted on the holder. Therefore, the restraint surface 25 has a flat shape. Since the constraining surface 25 has a flat shape, the angle formed with the central axis corresponding to the clearance angle is constant.

  On the other hand, the clearance angle of the main flank 21 in the present embodiment is not constant but increases as it approaches the second cutting edge 15. Specifically, the clearance angle of the main flank 21 at the portion located below the region close to the second cutting edge 15 in the first cutting edge 13 is the second cutting edge in the first cutting edge 13. 15 is configured to be larger than the clearance angle of the main flank 21 at the portion located below the region far from 15.

In other words, the clearance angle of the main flank 21 decreases as the distance from one of the pair of adjacent corner flank 23 decreases, and becomes a minimum value at a portion away from the second flank 23. And the clearance angle of the main flank 21 becomes large as it approaches the other of a pair of 2nd flank 23 adjacent from the part used as this minimum value.

  In the insert 1 of the present embodiment, as shown in FIGS. 4 to 9, the clearance angle of the main clearance surface 21 is θ1 = 15.9 °, θ2 = 14.55 °, θ3 = 14.39 °, θ4. = 14.32 °, θ5 = 14.7 °, and θ6 = 17.3 °. As described above, the clearance angles θ1, θ2, and θ3 become smaller as the distance from one of the pair of adjacent second cutting blades 15 (second cutting blade 15 located at the lower right in FIG. 2) increases. Further, the clearance angles θ4, θ5, and θ6 become smaller as the distance from the other of the pair of adjacent second cutting edges 15 (second cutting edge 15 located at the lower left in FIG. 2) increases. Of the clearance angles θ1 to θ6, the clearance angle θ4 located below the region closest to the center of the first cutting edge 13 is the minimum value of these clearance angles.

  By forming the clearance angle of the main flank 21 as described above, a large area of the restraint surface 25 located below the portion of the first cutting edge 13 close to the second cutting edge 15 is secured. be able to. Therefore, the area of the region located below the portion near the second cutting edge 15 on the constraining surface can be increased, and the constraining surface 25 can be brought close to the first cutting edge 13 in this region. Thus, since the area in the area | region away from the through-hole 11 among the restraint surfaces 25 can be enlarged, it is suppressed that the insert 1 rotates and the insert 1 can be stably fixed to a holder.

  On the other hand, since the clearance angle of the main flank 21 at a portion away from the second cutting edge 15 is relatively small, the first cutting edge 13 is positioned below a portion far from the second cutting edge 15. It can suppress that the restraining surface 25 approaches the cutting blade 9 too much. Therefore, the durability of the first cutting edge 13 can be kept high in a portion of the first cutting edge 13 away from the second cutting edge 15.

  In the insert 1 of the present embodiment, a portion of the first cutting edge 13 that is located above the region where the clearance angle of the main flank 21 is the smallest is a pair of first blades that are located with the first cutting edge 13 in between. The linear distances to the two cutting blades 15 are equal to each other.

  Further, in the insert 1 of the present embodiment, the side surface 7 has a stepped portion 27 between the main flank 21 and the restraining surface 25. At this time, the step between the main flank 21 and the restraining surface 25 in the stepped portion 27 becomes smaller as the second cutting edge 15 is approached.

  The first cutting edge 13 in the insert 1 of the present embodiment has a shape that slightly protrudes toward the outside. Therefore, the flat constraining surface 25 is formed by providing a step portion 27 between the main flank 21 and the constraining surface 25 on the side surface 7. At this time, the step between the main flank 21 and the constraining surface 25 in the stepped portion 27 is configured as described above, so that the constraining located below the portion of the first cutting edge 13 close to the second cutting edge 15. A large area of the surface 25 can be secured.

  In the insert 1 of the present embodiment, the width of the land surface 17 increases as the second cutting edge 15 is approached. The strength of the cutting edge 9 increases as the width of the land surface 17 increases.

  As mentioned above, although the cutting insert of one Embodiment of this invention was demonstrated in detail using drawing, the cutting insert of this invention is not limited to the structure of this embodiment.

<Cutting tools>
Next, a cutting tool 101 according to an embodiment of the present invention will be described with reference to the drawings.

  The cutting tool 101 of this embodiment is provided with the holder 103 which has the rotation center axis | shaft Y, and the said some cutting insert 1 as shown to FIG. The holder 103 has a plurality of insert pockets 105 on the outer peripheral surface on the distal end side. The plurality of cutting inserts 1 are mounted in the insert pockets 105, respectively.

  The holder 103 has a substantially rotating body shape around the rotation center axis Y. A plurality of insert pockets 105 are provided at equal intervals on the outer peripheral surface on the tip side of the holder 103. The insert pocket 105 is a part to which the cutting insert 1 is attached, and is open on the outer peripheral surface and the front end surface of the holder 103. Specifically, the insert pocket 105 has a seating surface 107 that faces the rotation direction, and a plurality of constraining side surfaces 109 that are positioned in a direction intersecting the seating surface 107.

  Then, the cutting inserts 1 are respectively mounted in the plurality of insert pockets 105 provided in the holder 103. The plurality of cutting inserts 1 are mounted such that the cutting edge 9 protrudes outward from the outer peripheral surface, that is, to the side of the holder 103.

  In the present embodiment, the cutting insert 1 is attached to the insert pocket 105 with a screw 111. That is, the cutting insert 1 is inserted into the through hole of the cutting insert 1, the tip of the screw 111 is inserted into a screw hole (not shown) formed in the insert pocket 105, and the screw portions are screwed together to form the cutting insert. 1 is mounted on the holder 103.

  As the holder 103, steel, cast iron, or the like can be used. In the cutting tool 101 of this embodiment, steel with high toughness is used among these members.

<Manufacturing method of cut product>
Next, the manufacturing method of the cut workpiece of one Embodiment of this invention is demonstrated using drawing.

The cut workpiece is produced by cutting the work material 201. The manufacturing method of the cut workpiece in the present embodiment includes the following steps. That is,
(1) a step of rotating the cutting tool 101 represented by the above embodiment;
(2) a step of bringing the cutting edge 9 in the rotating cutting tool 101 into contact with the work material 201; and (3) a step of separating the cutting tool 101 from the work material 201;
It has.

  More specifically, first, as shown in FIG. 12, the cutting tool 101 is rotated around the axis, and the cutting tool 101 is relatively brought close to the work material 201. Next, as shown in FIG. 13, the cutting blade 9 in the cutting tool 101 is brought into contact with the work material 201 to cut the work material 201. Then, as shown in FIG. 14, the cutting tool 101 is relatively moved away from the work material 201.

  In the present embodiment, the work material 201 is fixed, and the cutting tool 101 fixed around the axis Y is rotated and brought close to the work material 201. In FIG. 13, the work material 201 is cut by bringing the cutting edge 9 of the rotating insert 1 into contact with the work material 201. Further, in FIG. 14, the cutting tool 101 is rotated away from the work material 201.

In the cutting in the manufacturing method of the present embodiment, the cutting tool 101 is brought into contact with the work material 201 by moving the cutting tool 101 in each step, or the cutting tool 101 is separated from the work material 201. However, as a matter of course, it is not limited to such a form.

  For example, the work material 201 may be brought close to the cutting tool 101 in the step (1). Similarly, in the step (3), the work material 201 may be moved away from the cutting tool 101. In the case of continuing the cutting process, the state in which the cutting tool 101 is rotated may be maintained, and the process of bringing the cutting edge 9 in the cutting insert 1 into contact with a different part of the work material 201 may be repeated.

  Note that typical examples of the material of the work material 201 include carbon steel, alloy steel, stainless steel, cast iron, and non-ferrous metal.

1. Cutting insert (insert)
DESCRIPTION OF SYMBOLS 3 ... Upper surface 5 ... Lower surface 7 ... Side surface 9 ... Cutting blade 11 ... Through-hole 13 ... 1st cutting blade 15 ... 2nd cutting blade 17 ... Land Surface 19 ... Rake surface (inclined surface)
21 ... main flank 23 ... second flank 25 ... constraining surface 27 ... stepped portion 29 ... rising surface 31 ... flat surface 101 ... cutting tool 103 ... Holder 105 ... Insert pocket 107 ... Seating surface 109 ... Restraint side 111 ... Screw 201 ... Work material

Claims (6)

A substantially polygonal upper surface, a lower surface, a side surface positioned between the upper surface and the lower surface, a cutting edge formed at a line of intersection of the upper surface and the side surface, and a center of the upper surface from the lower surface. A cutting insert with a through hole formed toward the center,
The cutting edge includes a first cutting edge formed at a position corresponding to a side portion of the upper surface, and a second cutting edge formed at a position corresponding to a corner portion of the upper surface, The first cutting edge is located outward from a virtual straight line connecting the respective boundaries between one cutting edge and the pair of second cutting edges adjacent to the first cutting edge;
The side surface is located along the first cutting edge, and has a main flank surface that inclines so as to approach the through hole from the upper surface side toward the lower surface side, and below the main flank surface And a flat constraining surface located below the step portion,
The cutting insert according to claim 1, wherein a clearance angle of the main flank increases as it approaches the second cutting edge. The upper surface has a land surface that is located on the outer periphery and is connected to the cutting edge, and an inclined surface that is located inside the land surface and is inclined so as to approach the lower surface as it approaches the through hole,
The cutting insert according to claim 1, wherein the width of the land surface decreases as the distance from the second cutting edge increases.   The cutting insert according to claim 2, wherein a region having the smallest clearance angle on the main clearance surface is positioned below a region having the smallest width on the land surface.   The portion of the first cutting blade located above the region where the clearance angle of the main flank is the smallest is up to each of the pair of second cutting blades located with the first cutting blade in between. The cutting insert according to claim 1, wherein the linear distances are equal to each other. A holder having a plurality of insert pockets on the tip side;
The cutting tool provided with the cutting insert as described in any one of Claims 1-4 with which the said cutting blade was mounted | worn with the said insert pocket so that the side of the said holder might protrude. Rotating the cutting tool according to claim 5;
Contacting the work piece with the cutting edge in the rotating cutting tool;
The manufacturing method of the cut workpiece provided with the process of separating the said cutting tool from the said workpiece.

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