JP5938868B2 - Cutting insert and cutting edge changeable cutting tool - Google Patents

Description

  The present invention relates to a clamping mechanism for a cutting insert, and more particularly, to a cutting insert that is detachably attached to a cutting edge exchanging cutting tool used for a turning process, and a cutting edge exchanging cutting tool to which the cutting insert is attached.

  As a cutting insert attached to a cutting edge exchangeable cutting tool for turning, and a cutting edge exchangeable cutting tool to which the cutting insert is attached, for example, one described in Patent Document 1 (Japanese Patent Laid-Open No. 2004-284010) is disclosed. Are known. The cutting insert of patent document 1 has a rectangular plate-shaped insert main body, and the cutting edge is formed in the side ridge part of a pair of rectangular surface of an insert main body. Of the pair of rectangular surfaces, the first rectangular surface is formed with a groove extending in one diagonal direction, and the inclined surface descends toward the groove from two corners located on the other diagonal line. Are formed respectively.

  The second rectangular surface is formed with a groove extending in the other diagonal direction of the first rectangular surface when viewed from the first rectangular surface side, and is aligned in the one diagonal direction. A slope that descends from the two corners toward the groove is formed. That is, the insert body has a shape that is twisted around two axes that are orthogonal to the center line connecting the centers of the first and second rectangular surfaces and orthogonal to the side surfaces of the four insert bodies. Has been.

  This cutting insert is detachably attached to an insert mounting seat formed in a tool body of a cutting edge exchange type cutting tool. The bottom surface of the insert mounting seat faces the tool rotation direction, and the shape of the bottom surface is a support surface complementary to the first rectangular surface, and the first rectangular surface is supported by the bottom surface. Also, two side surfaces of the insert body intersecting with the groove of the first rectangular surface are supported by two flat wall surfaces facing the tool body front end side and the outer peripheral side of the insert mounting seat.

  By the way, since the cutting insert of this patent document 1 is supported and attached to the two support surfaces of the insert mounting seat in this way, for example, it faces the tool body front end side of the insert mounting seat. The support surface of the wall surface needs an area sufficient to support the side surface of the insert body. Furthermore, a thickness necessary for receiving the cutting load in the rotation axis direction acting on the insert main body must be secured on the rear end side of the support surface in the tool main body.

  However, when the area of the support surface facing the front end side of the insert mounting seat is increased in this way and a sufficient thickness is secured in the tool body on the rear end side, for example, the rear end side of the insert mounting seat is large. Chip pockets cannot be formed to improve chip discharge. In addition, even if it is attempted to mount a cutting insert by forming a plurality of insert mounting seats facing one chip discharge groove, a sufficient interval must be ensured between adjacent insert mounting seats. One cutting edge row must be formed by the plurality of cutting inserts of the plurality of chip discharge grooves, resulting in a reduction in processing efficiency.

  On the other hand, the cutting insert described in Patent Document 1 requires a sufficient area for the support surface of the insert mounting seat facing the outer peripheral side of the tool main body, and the tool diameter acting on the insert main body on the inner peripheral side of the tool main body. A wall thickness that can handle the cutting load in the direction must be secured. For this reason, a large chip pocket cannot be formed on the inner peripheral side of the insert mounting seat. In particular, in a very small diameter cutting edge exchangeable cutting tool, if a plurality of insert mounting seats are formed in the circumferential direction, a sufficient thickness cannot be ensured. Therefore, only one cutting insert can be attached in the circumferential direction, and it is not possible to avoid a decrease in machining efficiency.

JP 2004-284010 A

  The present invention is made under such a background, and there is no need for a plurality of support surfaces on the wall surface of the insert mounting seat, so that the insert mounting seat rear side and inner peripheral side of the cutting edge exchangeable cutting tool can be provided. The purpose of the present invention is to provide a cutting insert capable of improving chip efficiency by forming a large chip pocket and improving chip discharging performance, and by attaching more cutting inserts in the rotation axis direction and circumferential direction of the tool body. It is said. Moreover, this invention aims at providing the blade-tip-exchange-type cutting tool which attached the said cutting insert.

  A cutting insert according to an aspect of the present invention is a cutting insert that is detachably attached to an insert mounting seat of a cutting edge exchangeable cutting tool, and includes any one of the following configurations.

(1) A cutting insert that is detachably attached to an insert mounting seat of a cutting edge exchangeable cutting tool,
A polygonal plate-like insert body having a pair of polygonal surfaces and a plurality of side surfaces arranged around the polygonal surfaces,
A cutting edge is formed on the side ridge of the polygonal surface,
The insert body is a reverse-inverted symmetrical shape with respect to the pair of polygonal surfaces,
The pair of polygonal surfaces is a seating surface on which the other polygonal surface is seated on the bottom surface of the insert mounting seat when one of the polygonal surfaces is a rake face,
The pair of polygonal surfaces are each formed with a pair of contact surfaces disposed so as to be located on the pair of insert-side virtual planes,
The pair of abutting surfaces are formed on the pair of abutting surfaces formed on the bottom surface of the insert mounting seat when the polygonal surface on which the pair of abutting surfaces are formed is the seating surface. Each can be contacted,
In the insert body, a mounting hole is formed around an insert center line connecting the centers of the pair of polygonal surfaces,
The pair of insert-side virtual planes includes one insert-side virtual straight line that is orthogonal to the insert center line in each of the pair of polygonal surfaces, and the insert side is viewed from a direction along the insert-side virtual straight line. It is arranged in the direction that intersects each other in an X shape with the virtual straight line as the intersection,
Among the side surfaces of the insert body, the one side surface with respect to one polygonal surface facing one direction out of two directions in which the insert-side virtual straight line of the pair of contact surfaces extends, An abutting portion that can abut on an abutted portion formed on one wall surface that rises with respect to the bottom surface of the insert mounting seat is formed.

(2) In the above (1), the insert body has a shape that is 180 ° rotationally symmetric with respect to the insert center line,
The insert body is rotated 180 ° around the insert center line on the other side surface with respect to one polygonal surface facing the other direction of the two directions in which the insert-side virtual straight line extends. Another contact portion that can contact the contacted portion when formed is formed.

(3) In the above (2), each of the polygonal surfaces of the insert body has a rectangular shape,
The insert body has a pair of long side surfaces arranged on opposite sides and a pair of short side surfaces arranged on opposite sides,
A main cutting edge is formed on each of the side ridges intersecting each long side surface of each polygonal surface,
The insert-side imaginary straight line extends in a direction intersecting with the long side surface when viewed from the direction facing the polygonal surface, and the contact portion is formed on the long side surface.

  (4) In the above (3), the main cutting edge gradually increases in the insert center line direction from one corner portion of the polygonal surface to the other corner portion when viewed from the direction facing the long side surface. It inclines so that it may go to the opposite polygon side.

(5) In the above (3) or (4), the polygonal surface of the insert body has a parallelogram shape having a pair of obtuse corner portions and a pair of acute corner portions,
A corner blade connected to the main cutting edge is formed at the acute corner portion of each polygonal surface,
Sub-cutting blades connected to the corner blades are respectively formed on the side of the acute corner portion of the side ridge portion intersecting the short side surfaces of the polygonal surfaces,
The insert-side imaginary straight line extends in a direction orthogonal to the long side surface when viewed from the direction facing the polygonal surface.

  (6) In the above (5), the main cutting edge is inserted from the acute corner portion of the polygonal surface having a parallelogram shape toward the obtuse corner portion as viewed from the direction facing the long side surface. It inclines so that it may go to the polygon surface side on the opposite side gradually in the center line direction.

  (7) In any one of the above (1) to (6), the pair of contact surfaces are formed on the inner side of the polygonal surface with a gap from the side ridge portion.

  (8) In any one of the above (1) to (7), each of the pair of contact surfaces includes a plurality of contact surface portions spaced apart from each other and disposed along the pair of virtual sides on the insert side. doing.

  (9) In any one of the above (1) to (7), the pair of contact surfaces are respectively continuous along the pair of virtual sides on the insert side.

Moreover, the blade edge | tip-exchange-type cutting tool of this invention is equipped with the following structures.
(10) A cutting edge exchangeable cutting tool,
A tool body rotated about an axis,
The outer periphery of the tool body is detachably attached, and includes any one cutting insert of (1) to (9),
In the tool body, one or more insert mounting seats are formed with the one wall surface rising in the tool rotation direction with respect to the bottom surface with the bottom surface facing the tool rotation direction,
On the bottom surface of the insert mounting seat, a pair of contacted surfaces that come into contact with the pair of contact surfaces of the polygonal surface as the seating surface of the cutting insert are respectively a pair of mounting seat side virtual surfaces. Formed along a plane,
The pair of mounting seat side virtual planes includes one mounting seat side virtual straight line that extends on the bottom surface and intersects the one wall surface, and faces the one wall surface along the mounting seat side virtual straight line. As seen from the above, the pair of insert-side virtual planes of the polygonal surface as the seating surface intersect with each other in an X-shape complementary to the X-shape formed when viewed in a direction along the insert-side virtual straight line. Arranged in the direction to
A contacted portion that contacts the contact portion of the cutting insert is formed on the one wall surface of the insert mounting seat.

  In the cutting insert or cutting edge exchange type cutting tool having the above-described configuration, when one of the pair of polygonal surfaces of the insert body is a rake surface and the other is a seating surface as described above, the seating surface is used. A pair of contact surfaces formed on the polygonal surfaces are brought into contact with a pair of contacted surfaces on the bottom surface of the insert mounting seat.

  Here, the pair of insert-side virtual planes on which the pair of contact surfaces are disposed include insert-side virtual straight lines extending on the polygonal surfaces on which the pair of contact surfaces are formed, and the insert-side virtual planes. They are arranged in a direction crossing each other in an X shape when viewed from the direction along the straight line. On the other hand, the pair of mounting seat side virtual planes on which the pair of contacted surfaces are formed also includes a mounting seat side virtual straight line extending on the bottom surface of the insert mounting seat, and the one of the above-mentioned one along the mounting seat side virtual straight line. When viewed from the direction facing the wall surface, the pair of insert-side virtual planes are arranged in a direction intersecting with each other in an X-shape complementary to the X-shape when viewed in the direction along the insert-side virtual straight line. Yes.

  Therefore, as described above, in a state where the pair of contact surfaces of the seating surface of the insert main body are in contact with the pair of contacted surfaces of the bottom surface of the mounting seat, each pair of insert-side virtual planes and mounting seat-side virtual surfaces The plane coincides with the imaginary straight line on the insert side and the imaginary straight line on the mounting seat, and the insert body is allowed to move in the direction along these imaginary straight lines, but the movement is restricted in other directions. The

  In the insert body, one wall surface that rises with respect to the bottom surface of the insert mounting seat on one side surface with respect to one polygonal surface that faces one of the two directions in which the virtual straight line extends. Since the contact portion that can contact the contacted portion formed is formed, by pressing the insert body against the bottom surface of the mounting seat and pressing it in this one direction, The abutting part comes into contact with the abutted part, and the movement of the insert body is restricted in the direction along the imaginary straight line, and is fixed to the insert mounting seat. That is, the insert body is fixed by the abutted surface of the bottom surface of the insert mounting seat and the abutted portion of one insert mounting seat wall surface, and no other wall surface is required.

  Therefore, when the wall surface on which the abutted portion is provided is disposed on the inner peripheral side of the tool body with respect to the bottom surface of the insert mounting seat of the tool body rotated about the axis, the wall surface on the rear end side of the tool body is reduced. The wall thickness of the tool body on the rear end side of the wall surface can be reduced, or the wall surface itself can be made unnecessary in some cases. For this reason, a long tip type cutting edge is formed by forming a large chip pocket on the rear end side of the tool body of the insert mounting seat to improve chip discharging performance, or forming the next insert mounting seat close to the axial direction. It becomes possible to easily set the arrangement of the cutting blades in the exchangeable cutting tool.

  On the other hand, when the wall surface on which the abutted part is provided is arranged on the tool body rear end side of the insert mounting seat, the wall surface on the inner peripheral side of the tool body is conversely reduced, or the tool body on the inner peripheral side of this wall surface The wall thickness of the inner peripheral wall surface itself can be made unnecessary. Accordingly, the insert pocket on the inner peripheral side of the insert mounting seat is enlarged, or even a cutting tool with a very small diameter can be installed with a plurality of insert mounting seats in the circumferential direction to mount more cutting inserts. be able to.

  Moreover, in the cutting insert of the said structure, the insert main body is made into the front-and-back inversion symmetrical shape, The above-mentioned one side surface which faces one direction among the two directions where the insert side virtual straight line is extended about each of a pair of front and back polygonal surfaces. A contact portion is formed. Therefore, by reversing the insert body and reattaching it to the insert mounting seat, these polygonal surfaces are alternately raked and seated, and the polygonal surface is raked at least twice with one insert body. It becomes possible to use the cutting blade formed in the side ridge part.

  Furthermore, this insert main body is shaped to be 180 ° rotationally symmetric with respect to the insert center line orthogonal to the insert side virtual line of the pair of polygonal surfaces, and faces the other direction of the two directions in which the insert side virtual line extends. Another contact surface that can contact the contacted portion when the insert body is rotated 180 ° around the center line on the other side surface with respect to one polygonal surface. By forming the portion, it is possible to use the cutting blade four times in total with one insert body, two times for each polygonal surface.

  For example, each of the polygonal surfaces of the insert body has a quadrangular shape, and the insert body has a pair of long side surfaces disposed on opposite sides and a pair of short side surfaces disposed on opposite sides. The main cutting edges are respectively formed on the side ridges intersecting the long side surfaces of the polygonal surfaces, and the long side surfaces are viewed from the direction facing the polygonal surface of the insert-side virtual straight line. If the abutting portion is formed on the long side surface so as to extend in a direction intersecting with the main cutting edge formed on the intersecting ridge line portion between the long side surface and the quadrangular polygonal surface with one insert body Can be used at least 4 times. Further, by forming the contact portion on the long side surface, the contact length of the insert mounting seat with the contacted portion can be increased, and the seating stability of the cutting insert can be improved.

  In this way, when the polygonal surface has a quadrangular shape and the insert body has a pair of long side surfaces and short side surfaces, the main cutting edge is viewed from the direction facing the long side surfaces, and the When it is inclined toward the polygonal surface on the opposite side gradually toward the insert centerline direction from one corner of the square surface toward the other corner, the one corner and the other corner Since the height of the insert center line direction is different, the polygonal surface is a complex twisted surface. Even a cutting insert composed of such a complex twisted polygonal surface is paired on the polygonal surface. The above functions can be achieved by forming a pair of contact surfaces extending along the insert-side virtual plane.

  In particular, when the polygonal surface of the insert main body is formed into a quadrangular shape in this way, the polygonal surface of the rectangular shape is a parallelogram having a pair of obtuse corner portions and a pair of acute corner portions. A corner blade connected to the main cutting edge is formed at the acute corner portion, and the corner blade side of the side ridge portion intersecting the short side surface of each polygonal surface is the corner blade side. Are formed on the long side surface by disposing the insert side virtual straight line in a direction orthogonal to the long side surface as viewed from the direction facing the polygonal surface. A more stable cutting insert can be attached by pressing the contact portion to be perpendicular to the contact portion formed on the wall surface of the insert mounting seat.

  In this way, when the polygonal surface has a parallelogram shape, the obtuse angle from the acute corner portion of the polygonal surface forming the parallelogram shape when the main cutting edge is viewed from the direction facing the long side surface. The main cutting edge is directed to the outer peripheral side of the tool body by inclining toward the polygonal surface on the opposite side gradually toward the insert center line direction toward the corner, and the sub cutting edge is set to the tip of the tool body. When the insert body is attached to the insert mounting seat toward the side, a positive axial rake angle can be given to the main cutting edge.

  Further, by forming the pair of contact surfaces on the inner side of the polygonal surface at a distance from the side ridge portion, for example, a positive rake surface is formed in the outer peripheral side region of the polygonal surface and cutting is performed. It is possible to reduce the resistance. Moreover, even if the positive rake face is formed in this way, in the cutting insert having the above-described configuration, the polygonal face that is the seating face should not be brought into contact with the insert mounting seat except for the pair of contact faces. Therefore, it is possible to prevent the positive rake face and the cutting edge from being damaged when the insert is attached. In addition, by forming the contact surface in this way, even if the positive rake surface or cutting edge is damaged by cutting, it can be made less susceptible to the influence, so the insert body can be inverted or the insert center line When reattaching by rotating around 180 °, the cutting insert can be seated on the insert mounting seat regardless of the damage of the positive rake face or the cutting edge.

Each of the pair of contact surfaces may be configured to have a plurality of contact surface portions separated from each other as long as the pair of contact surfaces are disposed on the pair of insert side virtual planes as described above. You may form continuously along a pair of insert side virtual plane. For example, when an insert body having a small size is attached to the insert mounting seat by a clamp screw inserted through the mounting hole, the mounting hole through which the clamp screw is inserted opens into the pair of polygonal surfaces. The contact surface may be formed by a plurality of contact surface portions separated from each other so as to avoid the mounting hole.

  As described above, according to the cutting insert and the cutting edge replaceable cutting tool of the present invention, it is possible to secure a large chip pocket on the tool body rear end side or inner peripheral side of the insert mounting seat. In addition to being able to improve, it is possible to increase the number of cutting inserts that can be attached in the direction of the rotation axis or the circumferential direction of the tool body, thereby promoting efficient cutting.

It is a perspective view which shows 1st Embodiment of the cutting insert of this invention. It is a top view of embodiment shown in FIG. It is a side view of embodiment shown in FIG. It is a front view of embodiment shown in FIG. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a cutting edge exchangeable cutting tool of the present invention to which a cutting insert according to a first embodiment is attached. It is an enlarged plan view of the front-end | tip part of embodiment shown in FIG. It is an enlarged side view of the front-end | tip part of embodiment shown in FIG. FIG. 6 is an enlarged front view of the embodiment shown in FIG. 5. It is a perspective view of the tool main body which removed the cutting insert from embodiment shown in FIG. FIG. 10 is an enlarged plan view of the distal end portion of the tool body shown in FIG. 9. It is an enlarged side view of the front-end | tip part of the tool main body shown in FIG. FIG. 10 is an enlarged front view of the tool body shown in FIG. 9. 8 is an enlarged front view of the embodiment shown in FIG. 8 as viewed from a direction perpendicular to an imaginary straight line on the insert side on a polygonal surface (parallelogram surface) which is a seating surface of one cutting insert (the right cutting insert in FIG. 8). FIG. FIG. 14 is a partial enlarged cross-sectional view taken along the line AA in FIG. 13 (a cross-sectional view orthogonal to the insert-side imaginary straight line and the mounting seat-side imaginary straight line of the parallelogram surface as the seating surface). FIG. 14 is a partial enlarged cross-sectional view taken along the line BB in FIG. 13 (a cross-sectional view orthogonal to the insert-side imaginary straight line and the mounting seat-side imaginary straight line of the parallelogram surface as the seating surface). It is an AA partial expanded sectional view in FIG. It is BB partial expanded sectional view in FIG. FIG. 18 is an enlarged cross-sectional view of the main cutting edge in FIG. 17 (the upper right main cutting edge in FIG. 17). It is the figure which piled up the section of the insert main part shown in Drawing 16 and Drawing 17. FIG. 20 is a view for explaining the rake angle and clearance angle of the main cutting edge in FIG. 19 (enlarged view of portion A in FIG. 19). It is sectional drawing which shows the modification of the flank of the main cutting blade shown in FIG. It is sectional drawing which shows the other modification of the flank of the main cutting blade shown in FIG. It is the side view which looked at embodiment shown in FIG. 1 from the arrow X direction in FIG. It is a top view which shows the outline of a pair of polygonal surface of embodiment shown in FIG. It is the schematic which shows the flank formed in one long side surface of embodiment shown in FIG. It is a top view which shows the outline at the time of forming a pair of polygonal surface without twisting with respect to embodiment shown in FIG. It is the schematic which shows the flank formed in one long side surface in the case shown in FIG. It is a perspective view which shows 2nd Embodiment of the cutting insert of this invention. It is a top view of embodiment shown in FIG. It is a side view of embodiment shown in FIG. It is a front view of embodiment shown in FIG.

  1 to 4 show the external appearance of the first embodiment of the cutting insert of the present invention, and FIGS. 5 to 8 show the cutting edge exchangeable cutting tool of the present invention to which the cutting insert of the first embodiment is attached. 1 shows the appearance of one embodiment. Further, FIGS. 9 to 12 show the external appearance of the tool body in a state in which the cutting insert is removed in the cutting edge replacement type cutting tool of this embodiment.

  The cutting insert of this embodiment has an insert body 1. The insert body 1 is made of a hard material selected from cemented carbide, cermet, surface-coated cemented carbide, surface-coated cermet, etc., and has a polygonal plate shape, more specifically, a plate shape in which the polygonal surface forms a square shape, Specifically, a pair of parallelogram surfaces 2 in which a polygonal surface is formed in a plate shape having a substantially parallelogram shape, and a pair of acute corner portions A and obtuse corner portions B are alternately arranged in the circumferential direction; A pair of long side surfaces 3 and a pair of short side surfaces 4 that connect the side ridges are provided.

  The pair of parallelogram surfaces 2 is a seating surface on which the other parallelogram surface 2 is seated on the bottom surface of an insert mounting seat described later when one parallelogram surface 2 is a rake face. . In addition, although the insert main body 1 of this example has a parallelogram-shaped polygonal surface, the polygonal surface may be a rectangle. In that case, both end portions of one diagonal line may be regarded as an obtuse corner portion of the parallelogram surface 2 and both end portions of the other diagonal line may be regarded as acute corner portions.

  The insert body 1 is formed with a mounting hole 5 having a circular cross section centering on an insert center line C connecting the centers of the pair of parallelogram surfaces 2, and the mounting hole 5 extends in the direction of the insert center line C (insert The insert body 1 is penetrated in the thickness direction of the body 1. As shown in FIGS. 14 and 15, an annular reduced diameter portion 5 </ b> A is formed in the center portion of the mounting hole 5. The reduced diameter portion 5A has a cylindrical surface centered on the insert center line C with a narrow center portion in the insert center line C direction, and the cross section along the insert center line C has a convex curve shape on both sides thereof. A portion to be formed is formed.

  The insert body 1 has a symmetry line (not shown) extending in a direction perpendicular to the insert center line C and substantially parallel to the long side surface 3 at the center in the direction of the insert center line C, and perpendicular to the symmetry line and the insert center line C. And a symmetrical line N passing through the center of the long side surface 3, each having a 180 ° rotationally symmetric shape. That is, the insert body 1 has a front / back inversion symmetrical shape. The insert body 1 is also formed in a 180 ° rotationally symmetric shape with respect to the center line C. Therefore, as shown in FIG. 2, when viewed from the direction facing one parallelogram surface 2, the other parallelogram surface 2 is located at the acute corner portion A side of the one parallelogram surface 2. The obtuse corner portion B of the other parallelogram surface 2 is positioned at the obtuse corner portion B side of the one parallelogram surface 2.

  A main cutting edge 6A is formed in each of the side ridges of the pair of parallelogram surfaces 2 at the intersection ridgeline with the pair of long side surfaces 3, that is, the long side ridges of the parallelogram surface 2. The main cutting edge 6A is substantially straight when viewed from the direction facing the quadrilateral plane 2 parallel to the insert center line C direction. In addition, each of the side ridges of the pair of parallelogram surfaces 2 has an intersecting ridge line portion with the pair of short side surfaces 4, that is, on the acute corner portion A side of the short side ridge portion of the parallelogram surface 2, respectively. 6B is formed. When viewed from the direction facing the parallelogram surface 2 in the direction of the insert center line C, the auxiliary cutting edge 6B has a linear shape extending in a direction slightly intersecting the obtuse angle with respect to the main cutting edge 6A.

  Further, the intersecting ridge line portion between the long side surface 3 and the short side surface 4 is chamfered in a cross-sectional arc shape over the entire length, and the acute corner portion A of the side ridge portions of the parallelogram surface 2 has the above-mentioned cross-sectional circle. A corner blade 6C having a substantially ¼ arc shape when viewed from the direction facing the quadrilateral surface 2 parallel to the direction of the insert center line C is formed in the arc chamfered portion. The corner blade 6C is continuous with the main cutting edge 6A and the auxiliary cutting edge 6B. Further, the obtuse corner portion B of the parallelogram surface 2 is also chamfered in an arc shape.

  As shown in FIG. 3, the main cutting edge 6A is gradually separated from the corner edge 6C (acute corner portion A) toward the obtuse corner portion B as shown in FIG. The main cutting edge 6A is inclined substantially linearly at a substantially constant inclination angle so that the main cutting edge 6A is directed to the parallelogram surface 2 side opposite to the parallelogram surface 2 formed on the side ridge. It has been made. Therefore, as shown in FIG. 3, the long side surface 3 also has a substantially parallelogram shape and is inclined in the direction of the insert center line C in the longitudinal direction (vertical direction in FIG. 3), and is opposed to the long side surface 3. In a side view, the pair of main cutting edges 6A formed on one parallelogram surface 2 are arranged so as to intersect in an X shape.

  Further, as shown in FIG. 4, the auxiliary cutting edge 6B is gradually retracted in the direction of the insert center line C as it is separated from the corner edge 6C (acute corner portion A) in a side view facing the short side face 4, and on the opposite side. Are inclined substantially linearly at a substantially constant inclination angle so as to be directed to the parallelogram surface 2 side. Further, the corner blade 6C has a protruding end in the direction of the insert center line C at a position that bisects the ¼ arc in a side view, and is continuous so as to contact the main cutting edge 6A and the auxiliary cutting edge B. It is a convex curve.

  In addition, as shown in FIG. 2, when the portion other than the auxiliary cutting edge 6 </ b> B of the intersecting ridge line portion with the short side surface 4 in the side ridge portion of the parallelogram surface 2 is viewed from the direction facing the parallelogram surface 2. The secondary cutting edge 6B intersects with the obtuse angle and is substantially linear in contact with the arc-shaped chamfer formed in the obtuse corner portion B of the parallelogram surface 2. Further, as shown in FIG. 4, in the side view facing the short side surface 4, as it is separated from the secondary cutting edge 6B, it is steeper than the above-mentioned inclination angle formed by the secondary cutting edge 6B in the same side view and is in the direction of the insert center line C. After being gradually receded in a straight line, it extends in a direction substantially perpendicular to the insert center line C via the concave curve portion and is connected to the obtuse corner portion B.

  The pair of parallelogram surfaces 2 is formed with a positive rake face 2A that gradually recedes in the direction of the insert center line C toward the inside, inside the main cutting edge 6A, the auxiliary cutting edge 6B, and the corner cutting edge 6C. Has been. In the present embodiment, this positive rake face 2A is formed with a substantially constant width over the entire circumference of the parallelogram face 2, and in the cross section perpendicular to the sub cutting edge 6B and the corner edge 6C, the insert center The inclination angle with respect to the direction perpendicular to the line C is substantially constant.

  On the other hand, the positive rake face 2A is orthogonal to the main cutting edge 6A when viewed from the direction facing the parallelogram plane 2 as it is separated from the corner edge 6C (acute corner portion A) along the main cutting edge 6A. Thus, in the cross section extending in the direction of the insert center line C, the inclination angle with respect to the direction perpendicular to the insert center line C is gradually reduced. That is, the positive rake face 2A has a twisted surface shape with the rake angle gradually decreasing from the acute corner portion A side to the obtuse corner portion B side with respect to the main cutting edge 6A.

  Further, in the pair of parallelogram surfaces 2, a pair of contact surfaces 7 are formed between the positive rake surface 2 A and the opening of the mounting hole 5. The pair of contact surfaces 7 are arranged along the pair of insert side virtual planes P in each parallelogram surface 2, and the pair of insert side virtual planes P Each of the parallelogram surfaces 2 extending on the parallelogram surface 2 on which the contact surface 7 is formed includes one insert-side virtual straight line L, and from the direction along the insert-side virtual straight line L. As shown in FIG. 3, they are arranged in a direction intersecting with each other in an X shape with the insert-side virtual straight line L as an intersection.

  That is, the pair of insert-side virtual planes P is divided into two so that one plane including the insert-side virtual straight line L has a dividing line that intersects with the insert-side virtual straight line L. Two planes are twisted around the imaginary line L on the insert side, and an angle is formed so as to intersect in an X shape when viewed in the direction of the imaginary line L of the insert side. And a pair of contact surface 7 is arrange | positioned so that it may each be located on these pair of insert side virtual planes P. As shown in FIG.

  Further, of the long side surface 3 and the short side surface 4 of the insert body 1, one of two directions in which the insert side virtual straight line L of the insert side virtual plane P on which the pair of contact surfaces 7 are disposed extends. An abutting portion 8 is formed on one side surface of the parallelogram surface 2 that faces the direction and can abut against an abutted portion formed on one wall surface of an insert mounting seat described later. Yes. In the present embodiment, as shown in FIG. 3, the insert-side virtual straight line L extends between the pair of long side surfaces 3 when viewed from the direction facing the parallelogram surface 2. The long side surface 3 is formed.

  In this embodiment, the insert body 1 has a 180 ° rotationally symmetric shape with respect to the insert center line C. Therefore, the pair of insert-side virtual straight lines L respectively extending on the pair of parallelogram surfaces 2 are the center of the insert. It will be orthogonal to line C. And in the cutting insert of this embodiment formed in 180 degree | times rotation symmetrical shape regarding the insert centerline C in this way, one parallel four side which faces the other direction of the two directions where the said insert side virtual straight line L extends Another abutting portion 8 that can abut against the abutted portion when the insert body 1 is rotated 180 ° around the insert center line C also on the other long side surface 3 with respect to the profile surface 2. Is formed.

  Furthermore, in the cutting insert of this embodiment, the insert-side virtual straight line L of each parallelogram surface 2 is orthogonal to the long side surface 3 when viewed from the direction facing the parallelogram surface 2 along the insert center line C. It extends in the direction to do. Accordingly, these imaginary straight lines L on the insert side overlap with the symmetry line N passing through the center of the long side surface 3 as shown in FIG. 2 when viewed from the direction opposite to the quadrilateral surface 2 parallel to the insert center line C direction. It will be.

  Further, the pair of insert side virtual planes P on which the pair of contact surfaces 7 are disposed are each a pair of main cutting edges formed on each parallelogram surface 2 at the intersection ridge line portion with the long side surface 3. It arrange | positions so that 6A may be adjoined. Furthermore, the X-shaped inclination direction formed by the pair of insert-side virtual planes P when viewed in the direction of the insert-side virtual straight line L is the direction in which the main cutting edge 6A on the side adjacent to each insert-side virtual plane P faces the long side surface 3. The direction is the same as the X-shape when viewed from the top.

  Furthermore, each of the pair of contact surfaces 7 in the present embodiment is formed by a plurality of (two in the present embodiment) contact surface portions 7A and 7B which are disposed along the pair of insert-side virtual planes P. It is configured. Here, these contact surface portions 7A and 7B are formed between the pair of acute corner portions A of the parallelogram surface 2 and the obtuse corner portion between the substantially inner edge of the positive rake face 2A and the opening of the mounting hole 5. It is arranged on the B side. That is, in each of the pair of insert-side virtual planes P, the contact surface portions 7A and 7B are disposed on both sides of the insert-side virtual straight line L, so that the pair of contact surfaces 7 also have the insert-side virtual straight line L respectively. It extends across both sides of the bridge.

  Among these, the first contact surface portion 7A disposed on the side protruding in the X-shaped insert center line C direction formed by the pair of insert-side virtual planes P when viewed in the insert-side virtual straight line L direction is the parallelogram surface 2. Are formed on the first convex portion 9A that protrudes toward the inner edge of the positive rake face 2A in the acute corner portion A. As shown in FIG. 2, the first convex portion 9 </ b> A is an opening portion of the attachment hole 5 from the inside of the end portion of the auxiliary cutting edge 6 </ b> B opposite to the corner edge 6 </ b> C as seen from the direction of the parallelogram surface 2. Is formed so as to extend substantially parallel to the main cutting edge 6A connected to the acute corner portion A on the side where the first convex portions 9A are formed.

  Specifically, the first convex portion 9A has both ends in a direction substantially parallel to the main cutting edge 6A in a shape in which a truncated cone is halved along its center line, and a portion between them is the both end portions. As shown in FIGS. 16 and 17, the cross-section perpendicular to the direction in which the first convex portion 9A extends is formed in a substantially isosceles trapezoidal shape. The protruding end surface portion of the first convex portion 9A in the direction of the insert center line C is defined as the first contact surface portion 7A, and the first contact surface portion 7A is along the insert-side virtual plane P. The above-mentioned cross section, which is flat or has a protruding end along the insert-side virtual plane P, is a curved surface having a convex curve with a large curvature radius.

  Further, the second contact surface portion 7B disposed on the side retreating in the insert center line C direction in the X shape also has a positive rake surface 2A in the obtuse corner portion B on the obtuse corner portion B side of the parallelogram surface 2. It is formed on the second convex portion 9B protruding with respect to the inner edge. However, the protruding amount of the second convex portion 9B with respect to the inner edge of the positive rake face 2A at the obtuse corner portion B is made smaller than the protruding amount of the first convex portion 9A with respect to the inner edge of the positive rake face 2A. ing.

  Specifically, the second convex portion 9B extends in a diagonal direction connecting the pair of obtuse corner portions B of the parallelogram surface 2 when viewed from the direction facing the parallelogram surface 2, and the first convex portion The cross section orthogonal to the direction in which the portion 9A extends has an isosceles trapezoid shape that is flatter in the direction of the insert center line C than the first convex portion 9A as shown in FIGS. 16 and 17, and this second convex portion A flat protruding end surface of 9B is a second contact surface portion 7B. Further, the second contact surface portion 7B and the second convex portion 9B have a trapezoidal shape that gradually becomes wider toward the inside in the diagonal direction as viewed from the direction facing the parallelogram surface 2. .

  Then, the first and second contact surface portions 7A and 7B formed on the first and second convex portions 9A and 9B are arranged on the adjacent sides as shown in FIGS. Each pair of contact surfaces 7 is configured to be disposed on each one of the insert side virtual planes P adjacent to the cutting edge 6A. The opening of the attachment hole 5 is formed at an intermediate position between the first and second contact surface portions 7A and 7B in the insert center line C direction, and among these, the second contact surface portion 7B and the attachment hole 5 are formed. Between the opening, a boss 2B having a substantially conical outer shape centering on the insert center line C is formed.

  Here, as shown in FIG. 14, the inclination angles θ of the pair of insert-side virtual planes P when viewed from the direction along the insert-side virtual straight line L are mutually relative to the plane orthogonal to the insert center line C. Equally, the range is 5 ° to 25 °. In addition, the inclination angle with respect to the plane orthogonal to the insert center line C when viewed from the direction along the insert-side virtual straight line L of the main cutting edge 6A on the side where the pair of insert-side virtual planes P is adjacent is also 5 ° to 25 °. It is considered as a range. However, the inclination angle of the main cutting edge 6A may or may not be equal to the inclination angle θ of the insert-side virtual plane P. In the present embodiment, the inclination angle is slightly different.

  On the other hand, the flank (main flank) of the main cutting edge 6A is formed on the long side surface 3 of the insert body 1 where the contact portion 8 is formed as described above, and the sub cutting edge 6B is formed on the short side surface 4. A flank (sub-flank) is formed. Among these, the short side surface 4 includes a pair of parallelogram surfaces 2 in order from the sub cutting edge 6B of one parallelogram surface 2 to the other parallelogram surface 2 side in order. 4A, the 2nd sub relief surface 4B, and the negative surface 4C are formed.

  The first sub-flank 4A is connected to the sub-cutting edge 6B of one parallelogram surface 2 and is inclined so as to gradually protrude to the outside of the insert body 1 toward the other parallelogram surface 2 side, The second secondary flank 4 is also formed so as to gradually recede to the inside of the insert body 1 on the other side of the other parallelogram surface 2 with a steep slope rather than the slope of the first secondary flank. These first and second sub-flanks 4A and 4B are formed to have a substantially convex curved surface as shown in FIG. Further, the negative surface 4C extends from the second sub-flank 4B substantially parallel to the insert center line C and extends from the sub-cutting edge 6B of the other parallelogram surface 2 to the first sub-flank 4A and the second sub-flank. Crossed with the surface 4B and the negative surface 4C, the other parallelogram surface 2 is formed so as to reach between the obtuse corner portion B from the end opposite to the corner blade 6C of the sub cutting blade 6B. When viewed from the direction facing the parallelogram surface 2, the negative surfaces 4 </ b> C connected to the opposite end of the corner blade 6 </ b> C of the auxiliary cutting blade 6 </ b> B have a concave V shape.

  As shown in FIG. 4, in a side view as viewed from the direction facing the short side surface 4, the intersecting ridge line portion between the first auxiliary flank 4A and the second auxiliary flank 4B extends substantially parallel to the auxiliary cutting edge 6B. On the other hand, the intersecting ridge line portion between the second sub-flank 4B and the negative surface 4C extending from the second sub-flank 4B toward the other parallelogram surface 2 is in a direction perpendicular to the insert center line C. It extends. Further, in the same side view, the intersecting ridge line portion between the first auxiliary flank 4A and the negative surface 4C extends substantially parallel to the insert center line C from the end of the auxiliary cutting edge 6B opposite to the corner edge 6C. The cross ridge lines between the negative surfaces 4C extend along the insert center line C at the center of the short side surface 4, and the second sub-flank 4B and the other parallelogram so as to connect these cross ridge lines. The intersecting ridge line portion with the negative surface 4C extending from the surface 2 side extends obliquely toward the center portion of the insert center line C direction.

  Further, the long side surface 3 is formed with an intersection ridge line portion between the long side surface 3 and the pair of parallelogram surfaces 2 in order from the pair of parallelogram surfaces 2 toward the center portion in the direction of the insert center line C. A pair of the above-described main clearance surfaces 3A that are connected to the main cutting edge 6A, and convex curved surfaces that are connected to these main clearance surfaces 3A and protrude toward the outside of the insert main body 1 toward the center portion in the direction of the insert center line C. A pair of convex curved surface portions 3B that are curved to form a shape, and a concave curved surface shape that is continuous with these convex curved surface portions 3B and is located in the center portion of the long side surface 3 in the insert center line C direction and is recessed inside the insert body 1 One curved curved surface portion 3C is formed.

  In the present embodiment, the contact portion 8 is formed on the convex curved surface portion 3 </ b> B among the long side surfaces 3. Further, among the pair of convex curved surface portions 3B formed on one long side surface 3, one parallelogram surface 2 is a rake face, and a pair of main cutting edges 6A formed on the long side ridge portion. When one of the main cutting edges 6A is used for cutting, the other main cutting edge 6A opposite to the one main cutting edge 6A of the one parallelogram surface 2 is interposed through the main flank 3A. The abutting portions 8 formed on the convex curved surface portions 3B that are continuous with each other are brought into abutment with the abutted portions described later.

  Further, as shown in FIG. 3 in a side view facing the long side surface 3, the main flank 3A has an obtuse angle from the acute corner portion A of the main cutting edge 6A along the main cutting edge 6A connected to the main flank 3A. The width in the direction of the insert center line C gradually decreases toward the corner portion B, and the pair of convex curved surface portions 3B has an insert center line from the acute corner portion A on the side where the convex curved surface portions 3B are connected to the obtuse corner portion B. The width in the C direction is slightly increased gradually so that the one concave curved surface portion 3C has a substantially constant width in the center line C direction.

  The main relief surface 3A, the convex curved surface portion 3B, and the concave curved surface portion 3C as a whole are inclined in the direction of the insert center line C in the longitudinal direction of the long side surface 3 in the same manner as the long side surface 3. The curvature radius of curvature formed by the convex curved surface portion 3B and the curvature radius of curvature formed by the concave curved surface portion 3C are substantially constant in the longitudinal direction of the long side surface 3, that is, the convex curved surface portion 3B and the concave curved surface portion 3C. Is formed in an irregular cylindrical surface shape.

  On the other hand, as the main flank 3A moves away from the main cutting edge 6A in the cross section extending in the direction of the insert center line C perpendicular to the main cutting edge 6A when viewed from the direction facing the parallelogram surface 2, It is formed to be inclined so as to slightly protrude toward the outer side of the insert body 1, but its inclination angle with respect to the direction of the insert center line C is separated from the corner blade 6 </ b> C (acute corner portion A) along the main cutting edge 6 </ b> A. It is made to become small gradually according to.

  That is, the main clearance surface 3A is perpendicular to the insert center line C direction in a cross section extending in the insert center line C direction perpendicular to the main cutting edge 6A when viewed from the direction facing the parallelogram surface 2 in this way. The angle formed with the plane is gradually decreased along the main cutting edge 6A from the corner blade 6C (acute corner portion A) toward the obtuse corner portion B, and the clearance angle with respect to the main cutting edge 6A is the positive side. The twisted surface is formed so as to gradually increase. Therefore, in this embodiment, the convex curved surface portion 3B has a convex curved surface shape that protrudes from the main flank 3 to the outside of the insert main body 1 toward the center portion in the direction of the insert center line C and then goes inward.

  Moreover, in the cutting insert of this embodiment, as shown in FIG.2 and FIG.24 seeing from the direction which opposes the parallelogram surface 2 along the insert centerline C, a pair of parallelogram surface 2 is an insert centerline. The main cutting edge 6A is formed so as to be twisted by being slightly rotated around the C, so that the main cutting edge 6A intersects with a pair of parallelogram surfaces 2 being shifted. More specifically, as shown in FIG. 24, when viewed from the direction facing the parallelogram surface 2, the pair of parallelogram surfaces 2 are mutually connected to the main cutting on the acute corner portion A side of one parallelogram surface 2. The long side ridges on which the main cutting edge 6A is formed intersect each other so that the obtuse corner B of the other parallelogram surface 2 slightly protrudes from the blade 6A to the outside of the insert body 1.

  Further, as shown in FIG. 18, the main flank 3A itself includes a first main flank 3a having a convex arc shape connected to the main cutting edge 6A, and the center side of the first main flank 3a in the insert center line C direction side. And a second main flank 3b having a linear cross section. In the present embodiment, the width of the first main flank 3a in the direction of the insert center line C is substantially constant, and the width of the second main flank 3b gradually decreases from the acute corner portion A toward the obtuse corner portion B. Thus, the width of the main flank 3A is reduced from the acute corner portion A toward the obtuse corner portion B.

  If the main flank 3A itself is a torsional surface as described above, any one of the main flank 3A on the main flank 3A as shown in FIG. 22 may be a so-called eccentric flank where the clearance angle β is constant, or has a concave curve shape formed by the outer peripheral surface of the disc-type grindstone G as shown in FIG. Further, it may be a so-called concave flank, or may be a straight second surface having a straight line shape shown in FIG.

  FIGS. 5 to 8 show a cutting edge-replaceable cutting tool according to an embodiment of the present invention in which the above-mentioned cutting insert is detachably attached. FIGS. 9 to 12 show a cutting insert from this cutting-edge replaceable cutting tool. The removed state is shown. This cutting edge exchange type cutting tool is a cutting edge exchange type cutting tool, particularly an end mill, and has a tool body 11. The tool body 11 is formed of a steel material or the like and has a multi-stage columnar shape centered on the axis O. Among these, a rear end side portion (upper portion in FIGS. 5 and 9; FIGS. 7, 8, 10, and 11). The right portion is a shank portion 11A, and the tip portion is a cutting edge portion 11B.

  In such a blade-tip-exchangeable cutting tool, the shank portion 11A is held by the main spindle of the machine tool, and the tool body 11 is rotated in the tool rotation direction T around the axis O while intersecting the axis O (usually The workpiece is cut by the cutting blades (the main cutting blade 6A, the auxiliary cutting blade 6B, and the corner blade 6C) of the cutting insert attached to the cutting blade portion 11B by being fed in a direction perpendicular to the axis O). Go.

  On the outer periphery of the cutting edge portion 11B, there are a plurality of (two in this embodiment) tip pockets 12 at equal intervals in the circumferential direction, that is, the tip pockets 12 that open to the front end surface of the tool body 11 and extend to the rear end side. They are formed on opposite sides of the axis O. Furthermore, on the wall surface facing the tool rotation direction T side of these chip pockets 12, as shown in FIGS. 9 to 12, inserts that open to the front end surface and the outer peripheral surface of the cutting edge portion 11 </ b> B and are attached with the cutting inserts. The mounting seat 13 is formed so as to be recessed by one step from the wall surface to the rear side in the tool rotation direction T.

  The insert mounting seat 13 has a bottom surface 14 facing the tool rotation direction T, a wall surface 15 facing the outer peripheral side of the tool body 11, and a wall surface 16 facing the tip side of the tool body 11. Of the pair of parallelogram surfaces 2 of the insert body 1, when one parallelogram surface 2 is oriented as a rake face in the tool rotation direction T, the other parallelogram surface 2 serves as a seating surface on the bottom surface 14. Be seated. The wall surface 15 rises from the edge of the bottom surface 14 on the inner peripheral side of the tool body 11 toward the outer peripheral side and continues to the wall surface facing the tool rotation direction T of the chip pocket 12. The wall surface 16 rises from the edge of the bottom surface 14 on the rear end side of the tool body 11 toward the tool rotation direction T and continues to the wall surface of the chip pocket 12 facing the tool rotation direction T.

  However, the intersecting ridge line portion between the bottom surface 14 and the wall surfaces 15 and 16 and the intersecting ridge line portion between the wall surfaces 15 and 16 are disposed on the inner peripheral side of the tool body 11 of the other parallelogram surface 2 which is the seating surface. The main cutting edge 6A, the auxiliary cutting edge 6B disposed on the rear end side of the tool body 11, the corner blade 6C disposed on the inner peripheral side of the rear end, and the other of the long side surfaces 3 connected to the main cutting edge 6A. In order to avoid interference with the main relief surface 3A, the convex curved surface portion 3B, and the concave curved surface portion 3C on the parallelogram surface 2 side, the concave portion 17A is cut out.

  A main cutting edge 6A disposed on the outer peripheral side of the tool main body 11 of the parallelogram surface 2 which is also a seating surface is formed on the cross ridge line portion between the bottom surface 14 and the outer peripheral surface and the front end surface of the cutting edge portion 11B. In order to avoid interference with the auxiliary cutting edge 6B, the corner edge 6C arranged on the outer peripheral side of the tip, and the positive rake face 2A inside thereof, a chamfered relief portion 17B is formed.

  In the center of the bottom surface 14, a clamp inserted into the mounting hole 5 from one parallelogram surface 2 side, which is a rake face, with the insert body 1 seated on the insert mounting seat 13 as described above. A screw hole 14A into which the screw 18 is screwed is formed. As shown in FIG. 10, the screw hole 14 </ b> A is slightly inclined so as to go to the tool body rear end side from the opening to the bottom surface 14 toward the hole bottom side (rear side in the tool rotation direction T). . The insert body 1 is attached to the insert attachment seat 13 when the back surface of the head of the clamp screw 18 screwed into the screw hole 14A presses the reduced diameter portion 5A of the attachment hole 5. A concave relief portion 17 </ b> C for avoiding interference with the boss portion 2 </ b> B on the parallelogram surface 2 side, which is a seating surface, is also formed around the screw hole 14 </ b> A of the bottom surface 14.

  As shown in FIGS. 14 and 15, the bottom surface 14 has a pair of contact surfaces 19 on which the pair of contact surfaces 7 of the parallelogram surface 2 as a seating surface can contact. Are formed along the mounting seat side virtual plane Q. Here, in the present embodiment, the pair of contacted surfaces 19 are also shown in FIG. 9 and FIG. 10 or FIG. 14 and FIG. 15 similarly to the contact surface 7 in the cutting insert of the first embodiment. In addition, a plurality of (two in the present embodiment) contacted surface portions 19A and 19B arranged along the pair of mounting seat side virtual planes Q are formed.

  The pair of mounting seat side virtual planes Q also includes one mounting seat side virtual straight line M extending on the bottom surface 14, as in the case of the pair of insert side virtual planes P. When viewed along, they are arranged in an X-shaped crossing direction. Then, the inclination direction and the crossing angle of the pair of mounting seat side virtual planes Q when viewed in the mounting seat virtual straight line M direction are parallel to the seating surface when viewed in the insertion side virtual straight line L direction. The X-shape formed by the pair of insert-side virtual planes P is equal to the inclination direction and the crossing angle of the pair of insert-side virtual planes P of the quadrilateral surface 2. And an X shape complementary to the above.

  Furthermore, one mounting seat side virtual straight line M included in the pair of mounting seat side virtual planes Q is perpendicular to the center line of the screw hole 14A and rises from the bottom surface 14 when viewed from the direction facing the bottom surface 14, 16 extends so as to intersect one wall surface. In this embodiment, the mounting seat side virtual straight line M intersects the wall surface 15 facing the outer peripheral side of the tool main body 11, and the abutted portion that abuts the abutting portion 8 of the cutting insert on the wall surface 15. 20 is formed.

  This abutted portion 20 is located at the substantially central portion of the wall surface 15 rising from the edge on the inner peripheral side of the tool main body 11 of the bottom surface 14 to the rear side from the front end side of the tool main body 11 when viewed from the direction facing the wall surface 15. As it goes to the end side, it is inclined and extended so as to go to the outer peripheral side, and it is formed in a flat shape slightly inclined also to the tool rotation direction T side as it goes from the inner peripheral side to the outer peripheral side of the tool body 11. Here, the inclination of the contacted portion 20 with respect to the center line of the screw hole 14 </ b> A when viewed from the direction facing the wall surface 15 is the insert center line C when viewed from the direction facing the long side surface 3 of the insert body 1. The inclination and direction of the abutting portion 8 (convex curved surface portion 3B) are opposite to each other, and the inclination angles are substantially equal. A notch 20 </ b> A is formed at the center of the abutted portion 20.

  Further, the mounting seat side virtual straight line M is directed in the direction substantially perpendicular to the axis O of the tool body 11 or the inner peripheral side of the tool body 11 when viewed from the direction facing the bottom surface 14 in the center line direction of the screw hole 14A. Accordingly, the contacted portion 20 extends in a direction orthogonal to the mounting seat virtual straight line M. That is, the crossing angle formed by the mounting seat side virtual straight line M with respect to the contacted portion 20 when viewed from the center line direction of the screw hole 14A is the insert center line from the parallelogram surface 2 side which is the rake face of the cutting insert. An insert-side virtual straight line L on the parallelogram surface 2 that is a seating surface when viewed in the C direction is a convex curved surface portion 3B (a parallelogram that is a rake surface) on which a contact portion 8 with respect to the seating surface is formed. The crossing angle formed with respect to the convex curved surface portion 3B) on the shape surface 2 side is made equal.

  Therefore, in the present embodiment, the pair of contacted surfaces 19 are disposed on the outer peripheral side and the inner peripheral side of the tool body 11 of the bottom surface 14. Among these, the abutted surface 19 on the outer peripheral side is slightly inclined toward the rear side in the tool rotation direction T as it goes toward the rear end side of the tool body 11 as shown in FIGS. As shown in FIGS. 11 and 15, the circumferential contact surface 19 has a larger angle than the outer contact surface 19 toward the rear end side of the tool body 11, and the front side of the tool rotation direction T (the tool body). 11 on the outer peripheral side).

  Further, each of the two abutted surface portions 19A and 19B of the pair of abutted surfaces 19 is provided on the bottom surface 14 of the screw hole 14A at the tip outer periphery side, the rear end outer periphery side, the rear end inner periphery side, and the tip inner periphery. It is arranged on the side. That is, in each of the pair of mounting seat side virtual planes Q, the abutted surface portions 19A and 19B are disposed on both sides of the mounting seat side virtual straight line M, so that the pair of abutting surfaces 19 are also respectively mounted on the mounting seat. It is disposed on both sides of the side virtual straight line M. In addition, between the contact surface parts 19A and 19B on the front end side of the tool body 11 and between the contact surface parts 19A and 19B on the rear end side of the tool body 11 of the pair of contact surfaces 19 respectively, FIG. As shown in FIG. 16 and FIG. 17, a relief portion 17 </ b> D for avoiding interference with the first and second convex portions 9 </ b> A and 9 </ b> B of the insert body 1 is formed.

  In the insert mounting seat 13 formed in this way, the cutting insert is oriented in the tool rotation direction T with one parallelogram surface 2 of the insert body 1 as a rake face, and one long side surface 3 as described above. Is directed to the outer peripheral side of the tool body 11, one short side surface 4 is directed to the tip side of the tool body 11, and the other parallelogram surface 2 is seated on the bottom surface 14. At this time, in this embodiment, a total of four contact surface portions 7A and 7B of the other parallelogram surface 2 are in contact with a total of four contacted surface portions 19A and 19B, that is, a pair of contact surfaces 8. Are brought into contact with the pair of abutted surfaces 19 so that the insert side virtual plane P and the insert side virtual line L coincide with the mounting seat side virtual plane Q and the mounting seat side virtual line M.

  In this state, the insert body 1 has the insert center line C parallel to the center line of the screw hole 14A and the mounting seat side imaginary straight line M and the insert side imaginary straight line L in the other parallelogram surface 2 which are aligned with each other. Only movement in the direction along the direction is allowed, and is restricted in other directions. Therefore, with the insert main body 1 seated in this way, along the insert side virtual straight line L in the other parallelogram surface 2, toward the other long side surface 3 side opposite to the one long side surface 3, That is, when the insert body 1 is moved toward the inner peripheral side of the tool body 11, one parallelogram surface of the other long side surface 3 is brought into contact with the abutted portion 20 of the wall surface 15 as shown in FIGS. 16 and 17. The insert body 1 is positioned by contact of the contact portions 8 on the two sides.

  That is, (1) the intersection formed by the abutment portion 8 of the other long side surface 3 on the one of the parallelogram surfaces 2 and the imaginary line L on the other parallelogram surface 2 as viewed in the direction of the insert center line C. The crossing angle formed between the corner and the contacted portion 20 formed on the wall surface 15 of the insert mounting seat 13 and the mounting seat side virtual straight line M as viewed in the direction of the center line of the screw hole 14A is made equal to each other. (2) The convex curved surface portion 3B on which the abutting portion 8 is formed is a convex curved surface having a convex curve with a substantially constant curvature radius in the longitudinal direction of the long side surface 3, and the abutted portion 20 is a tool As it goes to the outer peripheral side of the main body 11, it is an inclined flat surface slightly inclined toward the tool rotation direction T side. For the reasons of (1) and (2) above, as shown in FIG. 16 and FIG. 17, the curved curved contact portion 8 is formed on the inclined flat contact portion 20 except for the notch 20A. Thus, the insert body 1 is stably positioned.

  Furthermore, in the state of being positioned in this way, the insert center line C, which is the center line of the mounting hole 5 of the insert body 1, is slightly eccentric to the outer peripheral side of the tool body 11 with respect to the center line of the screw hole 14A. Yes. Accordingly, when the clamp screw 18 is inserted from the attachment hole 5 and screwed into the screw hole 14A, the portion located on the inner peripheral side of the tool body 11 in the reduced diameter portion 5A of the attachment hole 5 by the back surface of the head of the clamp screw 18. Is pressed. Thereby, the insert body 1 is pressed against the bottom surface 14 by the clamp screw 18, and the abutting portion 8 formed on the convex curved surface portion 3 </ b> B on the side of the one of the parallelogram surfaces 2 on the other long side surface 3. It is detachably fixed to the insert mounting seat 13 so as to be pressed against the abutted portion 20.

  The main cutting edge 6A used for cutting toward the outer peripheral side of the tool body 11 of the one of the parallelogram surfaces 2 which is the rake face in a state of being fixed to the insert mounting seat 13 in this way is the tool body 11. Is substantially positioned on a cylindrical surface centered on the axis O of the axis or provided with a very small back taper, and a positive rake angle and a positive or 0 ° radial rake angle depending on the positive rake face 2A. Is given. In addition, a clearance angle of positive or 0 ° is also given to the main clearance surface 3A connected to the main cutting edge 6A. The main cutting edge 6A directed to the outer peripheral side of the tool body 11 of the other parallelogram surface 2 as the seating surface on the back side of the main cutting edge 6A is the main cutting edge 6A used for the above cutting. It is arranged inside the cylindrical surface, which is the rotation locus around the axis O, so as not to interfere with the processing surface of the work material, and is not used for cutting.

  On the other hand, the secondary cutting edge 6B used for cutting, which is connected to the main cutting edge 6A used for the above-described cutting via the corner blade 6C, is substantially positioned on a plane perpendicular to the axis O and has a radial direction of about 0 °. The rake angle and the positive rake face 2A give a positive axial rake angle, and the first and second auxiliary flank faces 4A and 4B also give a positive rake angle. The secondary cutting edge 6B directed to the tip side of the tool body 11 of the other parallelogram surface 2 serving as the seating surface is more than a plane perpendicular to the axis O where the secondary cutting edge 6B used for cutting is located. It is located on the rear end side of the tool body 11 and is never used for cutting.

  In the cutting insert according to the first embodiment and the cutting edge-exchangeable cutting tool according to the embodiment to which the cutting insert is attached, a pair of abutted members in which the insert body 1 is formed on the bottom surface 14 of the insert mounting seat 13 as described above. The wall surface 16 and the wall surface 16 of the insert mounting seat 13 facing the distal end side of the tool body 11 are fixed by being constrained and fixed by the abutted portion 20 formed on the wall surface 15 facing the outer peripheral side of the tool body 11. It is not involved in the installation. That is, in one embodiment of the directions in which the insert-side virtual straight line L extends with respect to one parallelogram surface 2, in this embodiment, only one abutting portion 8 of one long side surface 3 is an insert mounting seat. It is made to contact | abut to the one to-be-contacted part 20 of the one wall surface 13 of 13. FIG.

  For this reason, as shown in FIGS. 9 to 11, by forming a large chip pocket 12 on the rear end side of the tool body 11 of the insert mounting seat 13, the wall surface 16 becomes smaller, or the tool as shown in FIG. Even if there is a gap between the other short side surface 4 facing the rear end side of the main body 11 and the wall surface 16 or the wall surface 16 itself is not formed in some cases, the mounting of the cutting insert may be hindered. There is no. Therefore, even if the large chip pocket 12 is formed, the cutting insert can be stably held, and the chip discharge performance can be improved by the large chip pocket 12.

  5 to 12, only one insert mounting seat 13 is formed in the cutting edge portion 11B at the tip of the tool body 11 in the axis O direction. However, the present invention is not limited to this, and one or a plurality of insert mounting seats 13 can be formed on the rear end side of the insert mounting seat 13 to increase the number of blades of the tool. Even in such a case, according to the cutting insert and the cutting edge replacement type cutting tool, it is not necessary to form the wall surface 16 on the rear end side of the insert mounting seat 13 as described above. The mounting seat 13 can be formed in close proximity.

  For example, the insert mounting seat 13 adjacent to the rear end side in the direction of the axis O is shifted to the rear side in the tool rotation direction T by the thickness of the insert body 1 to be mounted on the row of insert mounting seats 13. It is also possible to form a cutting blade row in which the rotation trajectory of the main cutting blade 6A is continuous by the cutting insert. For this reason, it is possible to provide a large number of such cutting blade rows in one tool body 11, and it is possible to improve the cutting efficiency.

  In the cutting insert of the present embodiment, the insert body 1 has a reverse-inverted symmetrical shape. When the main cutting edge 6A, the auxiliary cutting edge 6B, or the corner edge 6C is worn, the insert body 1 is inserted. Is reversed and re-attached to the insert mounting seat 13 so that one parallelogram surface 2 which has been a rake face is used as a seating surface and the other parallelogram surface 2 which has been the seating face is used as a rake face. The main cutting edge 6A, the auxiliary cutting edge 6B, and the corner edge 6C formed on the side ridge portion of the other parallelogram surface 2 can be used.

  At this time, with respect to the parallelogram surface 2 as a new seating surface, the parallelogram surface 2 side as a new scoop surface of the new long side surface 3 positioned on the inner peripheral side of the tool body 11 is used. The abutting portion 8 is formed on the convex curved surface portion 3 </ b> B and abutted against the abutted portion 20 of the wall surface 15 of the insert mounting seat 13. That is, by reversing the insert main body 1 in this manner, the contact portion 8 of the opposite long side surface 3 can be brought into contact with the contacted portion 20 of the wall surface 15 of the insert mounting seat 13.

  In the present embodiment, the insert body 1 is also formed to be 180 ° rotationally symmetric with respect to the insert center line C. By rotating the insert body 1 around the insert center line C by 180 °, one parallelogram plane 2 is As it is, each pair of main cutting edge 6A, sub cutting edge 6B, and corner cutting edge 6C formed at the intersection ridge line portion with the pair of long and short side surfaces 3 and 4 and the acute corner portion A can be used. That is, in the cutting insert of this embodiment, the main cutting edge 6A, the auxiliary cutting edge 6B, and the corner cutting edge 6C can be used four times in total.

  At this time, with respect to one other parallelogram surface 2 which is a seating surface, the abutting portion 8 of the long side surface 3 opposite to the tip in the direction in which the insert-side virtual straight line L extends is insert-attached. The abutting portion 20 of the wall surface 15 of the seat 13 can be abutted. In this way, when the insert body 1 is rotated 180 ° around the insert center line C and attached to the insert mounting seat 13 and when the insert body 1 is attached with the front and back reversed, a pair of convex curved surface portions of the same long side surface 3 is provided. The abutting portions 8 formed on 3B are abutted against the abutted portions 20, respectively.

  That is, of the pair of front and back parallelogram surfaces 2, one long side surface 3 facing one direction in the direction of the insert-side imaginary straight line L in one parallelogram surface 2 and one other parallelogram surface 2. One long side surface 3 facing the other direction in the insert-side virtual straight line L direction is the same long side surface 3. Each will be formed.

  In addition, in the cutting insert of 1st Embodiment, seeing from the direction which opposes the parallelogram surface 2 in this way, the insert side virtual straight line L is made to cross | intersect the long side surface 3 of the insert main body 1, and this length While the abutting portion 8 is formed on the side surface 3, the mounting seat side virtual straight line M intersects the wall surface 15 facing the outer peripheral side of the tool body 11 of the insert mounting seat 13 in the cutting edge exchange type cutting tool of one embodiment. Although the contacted portion 20 is formed, the imaginary straight line L on the insert side intersects the short side surface 4 of the insert body 1 to form the contact portion 8 on the short side surface 4 and is also mounted on the insert mounting seat 13. The seat-side virtual straight line M may be intersected with the wall surface 16 facing the tip side of the tool body 11, and the contacted portion 20 may be formed on the wall surface 16.

  In this case, the wall surface 15 facing the outer peripheral side of the tool main body 11 in the insert mounting seat 13 can be prevented from being involved in the mounting of the cutting insert. The wall thickness of the main body 11 can be reduced, a space can be provided between the wall surface 15 and the long side surface 3, or the wall surface 15 itself can be made unnecessary depending on circumstances. For this reason, the chip pocket 12 has a large capacity on the inner peripheral side of the insert mounting seat 13 to improve chip discharging performance, or even a small number of blade-tip-exchangeable cutting tools can be mounted in the circumferential direction. Cutting efficiency can be improved by providing the seat 13 and attaching more cutting inserts.

  However, in particular, in a cutting edge-exchangeable cutting tool such as an end mill according to the above-described embodiment, the cutting load acting on the inner peripheral side of the tool body 11 from the main cutting edge 6A directed toward the outer peripheral side of the tool body 11 is greater than the tool body. 11 Since the cutting load acting on the rear end side of the tool body 11 from the auxiliary cutting edge 6B directed toward the tip end side becomes larger, the length of the insert body 1 that can secure a large contact area with this large cutting load. In order to maintain the mounting stability of the cutting insert, it is received by the abutting portion 8 and the abutted portion 20 formed on the wall surface 15 of the side surface 3 and the insert mounting seat 13 facing the outer peripheral side of the tool body 11. desirable.

  Moreover, in the cutting insert of 1st Embodiment, a pair of contact surface 7 is formed on a pair of insert side virtual plane P which cross | intersects X shape when it sees along the insert side virtual straight line L. The insert-side virtual straight line L is disposed on both sides of the insert-side virtual straight line L, and the pair of contact surfaces 19 of the insert-attaching seat 13 is also attached to the mounting-seat-side virtual straight line in the cutting edge exchangeable cutting tool of the embodiment. Formed on a pair of mounting seat side virtual planes Q intersecting in a complementary X shape with the insert side virtual plane P when viewed along M, and also straddling the mounting seat side virtual straight line M on both sides thereof It is arranged.

  For this reason, the abutment surface 7 and the abutted surface 19 are brought into contact with each other on both sides of the insert-side virtual straight line L and the mounting seat-side virtual straight line M, so that the insert-side virtual straight line L and the mounting seat-side virtual straight line M are highly accurate. Accordingly, it is possible to improve the mounting accuracy of the insert body 1 to the insert mounting seat 13, thereby pulling high-precision cutting. In addition, since the pair of contact surfaces 7 thus arranged in an X shape is supported by the pair of contacted surfaces 19 on both sides of the insert-side virtual straight line L, the mounting stability of the insert body 1 is also improved. be able to.

  Furthermore, in the cutting insert of the present embodiment, the abutted portion 20 formed on the wall surface 15 of the insert mounting seat 13 is inclined flat as described above, whereas the abutting portion 20 of the insert body 1 is A cross section extending in the longitudinal direction of the long side surface 3 is formed in a convex curved surface portion 3B having a substantially constant curvature radius. For this reason, for example, even if the insert body 1 is attached with a slight inclination around the symmetry line extending substantially parallel to the long side surface 3 due to its manufacturing error or the like, this inclination is along the curve of the convex curved surface portion 3B. Therefore, the contact portion 8 can be reliably brought into contact with the contacted portion 20.

  In the present embodiment, the positive rake face 2A connected to the main cutting edge 6A has a twisted surface shape in which the rake angle is gradually reduced from the acute corner portion A side toward the obtuse corner portion B side, The main flank 3A has a torsional surface shape in which the flank angle gradually increases toward the positive side as it moves away from the acute corner part A and toward the obtuse corner part B. Therefore, when the insert main body 1 is attached with a positive axial rake angle applied to the main cutting edge 6A as described above, the radial rake angle α and the clearance angle of the main cutting edge 6A as shown in FIGS. 19 and 20. β can be made substantially constant over the entire length of the main cutting edge 6A, and the blade angle of the main cutting edge 6A can also be made substantially constant, resulting in a partial increase in cutting resistance and a decrease in cutting edge strength. Thus, the main cutting edge 6A can be prevented from being damaged.

  By the way, in the case where the main flank 3A is formed in a twisted surface shape as described above, the main cutting edge 6A having a substantially straight line when viewed from the direction facing the parallelogram surface 2 is, for example, as shown in FIG. If the pair of parallelogram surfaces 2 overlap each other, the clearance angle of the main flank 3A gradually increases from the acute corner portion A side to the obtuse corner portion B side of the main cutting edge 6A toward the positive angle side. Accordingly, the amount of protrusion toward the outside of the insert body 1 on the inner side of the main flank 3A in the insert center line C direction gradually decreases, so that the acute corner portion A side of one parallelogram 2 as shown in FIG. The convex curved surface portion 3B continuous to the main clearance surface 3A of the main cutting edge 6A and the convex curved surface portion 3B continuous to the main clearance surface 3A of the main cutting edge 6A on the obtuse corner portion B side of the other parallelogram surface 2 are used as they are. When extended, these convexities in the longitudinal direction of the long side surface 3 Position face 3B intersect is shifted to the insert center line C direction.

  In such a case, the convex curved surface portion 3B connected to the main clearance surface 3A of the main cutting edge 6A on the obtuse corner portion B side becomes small, or in some cases, the convex cutting portion 6A protrudes toward the obtuse corner portion B side. It may be impossible to form the curved surface portion 3B itself. Accordingly, the contact portion 8 to be formed on the convex curved surface portion 3B is also reduced, and the contact portion 8 cannot be provided at the obtuse corner portion B. A contact area also becomes small, and there exists a possibility that it may become difficult to attach the insert main body 1 to the insert attachment seat 13 stably.

  On the other hand, if it is attempted to form the main cutting edge 6A at the intersecting ridge line portion between the torsion-shaped main relief surface 3A and the pair of parallelogram surfaces 2 while forcibly securing the width of the convex curved surface portion 3B, One parallelogram surface when the main cutting edge 6A on the other parallelogram surface 2 side is viewed from the direction facing the parallelogram surface 2 when the main cutting edge 6A on the parallelogram surface 2 side is used as a reference. It may be difficult to form the two main cutting edges 6A so as to overlap each other. Further, the radius of curvature of the curvature formed by the convex curved surface portion 3B must be changed toward the longitudinal direction of the long side surface 3, or the convex curved surface portion 3B itself and the contacted portion 20 must be formed in a twisted surface shape. Therefore, the shape of the contact portion 8 of the insert body 1 and the contacted portion 20 of the insert mounting seat 13 may be complicated.

  Therefore, in the cutting insert of this embodiment, in order to solve such a problem, the pair of parallelogram surfaces 2 are slightly rotated around the insert center line C and twisted as shown in FIG. 2 and FIG. Thus, the main cutting edge 6A is displaced between the pair of parallelogram surfaces 2 when viewed from the direction facing the parallelogram surface 2. That is, as shown in FIG. 24, the main cutting edge 6 </ b> A on the acute corner portion A side of one parallelogram surface 2 between the pair of parallelogram surfaces 2 as viewed from the direction facing the parallelogram surface 2. The long side ridges where the main cutting edge 6A is formed are crossed so that the obtuse corner part B of the other parallelogram surface 2 slightly protrudes outside the insert body 1.

In other words, the cutting insert of the present embodiment is a cutting insert that is detachably attached to an insert mounting seat of a cutting edge-exchangeable cutting tool, and has any of the following configurations.
(A) A cutting insert that is detachably attached to an insert mounting seat of a cutting edge exchangeable cutting tool,
A polygonal plate-like insert body having a pair of polygonal surfaces and a plurality of side surfaces arranged around the polygonal surfaces,
The pair of polygonal surfaces is a seating surface on which the other polygonal surface is seated on the bottom surface of the insert mounting seat when one of the polygonal surfaces is a rake face,
Cutting edges are respectively formed on a pair of side ridges intersecting the pair of polygonal surfaces of at least one of the side surfaces,
The insert body has a shape that is 180 ° rotationally symmetric with respect to a symmetry line passing through the center of the at least one side surface;
On the at least one side surface, flank surfaces of the cutting blades when the pair of polygonal surfaces are raked surfaces are formed on the pair of polygonal surface sides, respectively.
These flank faces have clearance angles with respect to the cutting edge as they go from one corner portion to the other corner portion in the circumferential direction of the pair of polygonal surfaces in the side ridge portion where the cutting edge is formed. Is formed in the shape of a twisted surface that gradually increases toward the positive angle side,
The pair of side ridges on which the cutting blades are formed are so that the other corner of one side ridge protrudes outside the other side ridge when viewed from the direction facing the polygonal surface. Crossed each other.

(B) In (A) above, each of the polygonal surfaces of the insert body is rectangular.
The insert body has a pair of long side surfaces arranged on opposite sides and a pair of short side surfaces arranged on opposite sides,
A main cutting edge is formed on each of the side ridges intersecting the pair of polygonal surfaces of the pair of long side surfaces,
The flank of the main cutting edge is formed in a torsional surface, and the side ridges where the main cutting edge is formed intersect with each other when viewed from the direction facing the pair of polygonal surfaces.

  (C) In the above (B), the main cutting edge is a pair of a plurality of multi-points as it goes from the one corner portion of the polygonal surface to the other corner portion when viewed from the direction facing the long side surface. It inclines so that it may go to the polygon surface side on the opposite side gradually in the insert center line direction which passes along the center of a square surface.

(D) In the above (B) or (C), the polygonal surface of the insert body has a parallelogram shape having a pair of obtuse corner portions and a pair of acute corner portions,
A corner blade connected to the main cutting edge is formed at the acute corner portion of each polygonal surface,
Sub-cutting blades connected to the corner blades are respectively formed on the side of the acute corner portion of the side ridge portion intersecting the short side surfaces of the polygonal surfaces,
The flank is formed in a twisted surface shape such that the flank with respect to the main cutting edge gradually increases toward the positive side as it goes from the acute corner to the obtuse corner.
The pair of side ridges on which the main cutting edge is formed are seen from the direction facing the pair of polygonal surfaces, and the obtuse corner portion of one side ridge protrudes outside the other side ridge. Are crossed with each other.

  (E) In the above (D), the main cutting edge, as viewed from the direction facing the long side surface, from the acute corner portion of the polygonal surface forming a parallelogram to the obtuse corner portion, It inclines so that it may go to the polygon surface side on the opposite side gradually in the insert center line direction passing through the center of a pair of polygon surfaces.

(F) In any one of the above (A) to (E), the insert body has a shape that is 180 ° rotationally symmetric with respect to an insert center line passing through the centers of the pair of polygonal surfaces, and Including at least a pair of the side surfaces formed with cutting edges,
When the cutting blade on one side is used for cutting, a pair of contact portions formed on the other side surface is formed on the pair of side surfaces. Has been.

Moreover, the blade edge | tip-exchange-type cutting tool of the said embodiment is equipped with the following structures.
(G) A cutting edge exchangeable cutting tool,
A tool body rotated about an axis,
A cutting insert that is detachably attached to the outer periphery of the tip of the tool body, and includes any one of the cutting inserts (A) to (F),
In the tool body, one or more insert mounting seats to which the cutting insert is attached are formed with the bottom surface facing the tool rotation direction,
The cutting insert has the at least one side surface directed toward the outer peripheral side of the tool body, and the one corner portion of the side ridge portion that intersects the polygonal surface that is the rake face of the side surface of the tool body. A positive axial rake angle is given to the cutting edge formed at the side ridge portion toward the distal end side, and the seating surface of the side surface is inside the rotation trajectory around the axis of the cutting edge. It is attached to the insert mounting seat so that the side ridge that intersects the polygonal surface is located.

(H) In the above (G), the cutting blades, as viewed from the direction facing the at least one side surface, move toward the other corner portion from the one corner portion of the polygonal surface, Inclined to gradually go to the opposite polygon side in the direction of the insert center line passing through the center of the polygon plane,
The cutting insert is attached to the insert mounting seat so that the insert center line is inclined toward the rear end side of the tool main body as it goes toward the polygonal surface side as a seating surface.

  Therefore, in the cutting insert of the present embodiment configured as described above, the main flank 3 </ b> A having a twisted surface from the acute corner portion A side toward the obtuse corner portion B side has a center portion in the direction of the insert centerline C direction. On the other hand, the main cutting edge 6A itself is the main cutting edge on the acute corner portion A side of the parallelogram surface 2 on the opposite side on the obtuse corner portion B side. Since it protrudes slightly to the outside of the insert body 1 with respect to 6A, the protruding position of the intersecting ridge line with the convex surface portion 3B of each other to the outside of the insert body 1 can be made substantially equal.

  For this reason, according to the cutting insert of the present embodiment, even if the curvature radius of the curvature formed by the convex curved surface portion 3B is substantially constant over the longitudinal direction of the long side surface 3 as described above, the obtuse corner portion B side Therefore, it is possible to prevent the width of the convex curved surface portion 3B from becoming too small or to prevent the convex curved surface portion 3B from being provided, and to secure a contact area between the contact portion 8 and the contacted portion 20; Stable attachment to the insert attachment seat 13 can be achieved. Further, the shape of the contact portion 8 of the insert main body 1 and the contacted portion 20 of the insert mounting seat 13 is not complicated.

  Furthermore, in this embodiment, while the pair of parallelogram surfaces 2 are twisted around the insert center line C, the main cutting edge 6A and the auxiliary cutting edge 6B connected via the corner blade 6C are parallel to each other. Since it is arranged in a direction crossing an obtuse angle when viewed from the direction facing the quadrilateral surface 2, the secondary cutting edge 6B directed to the tip side of the tool body 11 of the other parallelogram surface 2 which is the seating surface is The inner periphery of the tool main body 11 with respect to a plane perpendicular to the axis O on which the auxiliary cutting edge 6B used for cutting is directed toward the tip side of the tool main body 11 of one parallelogram surface 2 to be a rake face. As it goes to the side, it can be inclined and moved backward toward the rear end side. Therefore, it is possible to reliably prevent the secondary cutting edge 6B of the other parallelogram surface 2 from interfering with the finished surface formed by the secondary cutting edge 6B of the one parallelogram surface 2. In addition to improving the surface accuracy, it is also possible to perform a ramping process in which, for example, the tool body 11 is also sent in the direction of the axis O to dig up the work material obliquely.

  In addition, in this embodiment, the main cutting edge 6 </ b> A is formed to be inclined so as to recede in the direction of the insert center line C as it goes from the acute corner portion A to the obtuse corner portion B, and is formed on the bottom surface 14 of the insert mounting seat 13. As described above, the formed screw hole 14A is slightly inclined toward the rear end side of the tool body 11 toward the hole bottom side (rear side of the tool rotation direction T). Even if the insert body 1 is attached so that the line C faces the rear end side of the tool body 11 toward the parallelogram surface 2 side, which is also a seating surface, the main cutting edge 6A used for cutting is not correct. The rake angle in the axial direction can be given. And even if the insert main body 1 is inclined and attached in this way, the sub cutting edge 6B used for cutting is positioned in the sub cutting edge 6B on the tip side of the tool main body 11 of the parallelogram surface 2 which is the seating surface. Therefore, it is possible to more reliably prevent the interference with the finished surface and perform the ramping process smoothly.

  In addition, as shown in FIG. 24, the shift angle γ between the pair of parallelogram surfaces 2 that are shifted so as to be twisted by rotating around the insert center line C is about 1 ° to 10 °. desirable. If the deviation angle γ is smaller than 1 °, the above effect may not be achieved. If it is larger than 10 °, the obtuse corner portion located on the outer peripheral side of the tool body 11 of the other parallelogram 2 that is the seating surface. There is a possibility that B interferes with the work surface of the work material formed by the main cutting edge 6A of one parallelogram surface 2 which is a rake face.

  Further, when the pair of parallelogram surfaces 2 are twisted in this way and viewed from the direction facing the parallelogram surface 2, the pair of side ridge portions of the long side surface 3 on which the main cutting edge 6A is formed are In the case where the obtuse corner portion B of one side ridge portion intersects each other so as to protrude outside the other side ridge portion, the insert side virtual straight line L is exactly the same in the parallelogram plane 2. When viewed from the opposite direction, it is perpendicular to the symmetry line N and perpendicular to the imaginary long side surface circumscribing the obtuse corner portion B of the pair of side ridges. However, in this embodiment, when viewed from the direction facing the parallelogram surface 2 in this way, the insert-side virtual straight line L extends in the direction orthogonal to the long side surface 3 or the virtual long side surface, and the symmetry line N and Although they overlap each other, they may be inclined as long as they are within a range of about ± 10 ° with respect to the symmetry line N.

  Further, in the cross section orthogonal to the axis O of the tool body 11 as shown in FIG. 18, the radial rake angle α of the main cutting edge 6A is preferably in the range of 0 ° to 20 °. Further, as shown in FIG. 18, the main flank 3A has a first main flank 3a having a convex arc shape continuous with the main cutting edge 6A in a cross section perpendicular to the axis O of the tool body 11, and the first main flank 3a. In the case where the flank 3a is constituted by the second main flank 3b having a linear cross section that is continuous with the central portion in the direction of the insert center line C, the first main formed by the tangent line that touches the convex arc at the position of the main cutting edge 6A. The clearance angle β1 of the flank 3a is in the range of 0 ° to 15 °, the clearance angle β2 of the second main flank 3b is in the range of β1 to β1 + 20 °, and the radius R of the first main flank 3a is outside the main cutting edge 6A. The diameter (diameter) D is preferably in the range of D / 2 to 2 × D, and the width W of the first main relief surface 3a is preferably in the range of 0.03 × D to 0.15 × D.

  Furthermore, in the cutting insert of the first embodiment, each contact surface 7 is constituted by a plurality of contact surface portions 7A and 7B that are separated from each other along the insert-side virtual plane P. For this reason, for example, when the dimension of the insert body 1 is small and the area of the pair of parallelogram surfaces 2 is limited, the mounting hole for fixing the insert body 1 to the insert mounting seat 13 as in this embodiment. Even when 5 is open to the parallelogram surface 2, the pair of contact surfaces 7 (contact surface portions 7A and 7B) can be reliably disposed on both sides of the insert-side virtual straight line L, respectively. The mounting accuracy and mounting stability of the inserted insert body 1 can be further improved.

  However, when the size of the insert body 1 is large and a large area can be ensured also on the parallelogram surface 2, the cutting insert according to the second embodiment of the present invention shown in FIGS. Moreover, a pair of contact surfaces 7 may be formed continuously along the pair of insert-side virtual planes P, respectively. In the second embodiment, the same reference numerals are assigned to elements common to the first embodiment, and description thereof is omitted.

  In the cutting insert of the second embodiment, a pair of continuous abutment surfaces 7 are opposed to the parallelogram surface 2 inside the positive rake surface 2A of the pair of parallelogram surfaces 2 of the insert body 1. The main cutting edge 6A is formed along the pair of long side ridges as viewed from the direction. As in the first embodiment, these abutting surfaces 7 are also in the direction of the insert center line C in the direction from the acute corner portion A to the obtuse corner portion B of the parallelogram surface 2 in accordance with the inclination of the adjacent main cutting edge 6A. It is designed to gradually retreat.

  A step surface 7C is formed between a portion protruding in the direction of the insert center line C and a portion retracted between the contact surfaces 7 of each other. Further, a step surface 7D is also formed between the positive rake surface 2A in the portion on the acute corner portion A side where the contact surface 7 protrudes in the insert center line C direction. On the other hand, on the side where the contact surface 7 is retracted in the direction of the insert center line C, a boss portion 2B is formed between the opening portion of the mounting hole 5 as in the first embodiment. Further, in the second embodiment, only the first sub-flank 4A that recedes while forming a convex curved surface is formed from the sub-cutting blade 6B toward the inner side of the insert center line C, and intersected with the negative surface 4C. Yes.

  The cutting insert of such 2nd Embodiment can also be attached to the insert attachment seat 13 formed in the tool main body 11 of the blade-tip-exchange-type cutting tool of the said one Embodiment. In this case, since the pair of abutting surfaces 19 of the insert mounting seat 13 is constituted by a plurality of abutting surface portions 19A and 19B spaced apart from each other, the abutting on the abutting surface 7 is also separated from each other. It becomes a place.

  However, when the area of the bottom surface 14 of the insert mounting seat 13 can also be ensured, the pair of contacted surfaces 19 may be continuous along the mounting seat side virtual plane Q. In addition, when the cutting insert of the second embodiment is attached, it is possible to further increase the attachment stability by increasing the mutual contact area. Moreover, you may attach the cutting insert of 1st Embodiment to the insert mounting seat 13 which has such a continuous to-be-contacted surface 19. FIG.

  In the first and second embodiments, since the short side surface 4 does not participate in the attachment of the insert, the auxiliary relief surfaces 4A and 4B of the short side surface 4 and the pair of parallelogram surfaces 2 intersect. Even if the shapes of the auxiliary cutting edge 6B and the corner blade 6C formed on the ridge line are different, it is possible to attach them to the same insert mounting seat 13 as they are. Therefore, when a plurality of insert mounting seats 13 are formed in the direction of the axis O as described above, the cutting insert attached to the most advanced insert mounting seat 13 protrudes, for example, in the longitudinal direction of the auxiliary relief surfaces 4A and 4B. It can also be attached as a cutting insert in which a corner blade 6C having a large radius and a large radius is formed. That is, since a plurality of types of cutting inserts having corner radii 6C having different radii can be attached to one tool body 11, one tool body can be formed even when corners having different radii are formed during shoulder cutting. 11 can cope with this.

  In the first and second embodiments, the main flank 3 </ b> A has a twisted surface as described above, and the main cutting edge 6 </ b> A is formed as viewed from the direction facing the parallelogram surface 2. In the present invention, the pair of long side ridges overlap each other when viewed from the direction facing the parallelogram surface 2 as shown in FIG. In this case, the entire long side surface 3 is a flat negative relief surface extending in parallel to the insert center line C, and can be brought into contact with the flat contacted portion 20 as well. The contact portion 8 may be used.

  As described above, according to the cutting insert and the cutting edge replaceable cutting tool of the present invention, it is possible to secure a large chip pocket on the tool body rear end side or inner peripheral side of the insert mounting seat, and it is possible to remove chips. In addition to being able to improve, it is possible to increase the number of cutting inserts that can be attached in the direction of the rotation axis or the circumferential direction of the tool body, thereby promoting efficient cutting. Therefore, industrial use is possible.

DESCRIPTION OF SYMBOLS 1 Insert main body 2 Parallelogram surface 2A Positive rake surface 3 Long side surface 3A Main flank 3B Convex curved surface part 3C Concave curved surface part 4 Short side surface 5 Mounting hole 6A Main cutting edge 6B Sub cutting edge 6C Corner blade 7 Contact surface 7A, 7B Contact surface portion 8 Contact portion 11 Tool body 13 Insert mounting seat 14 Bottom surface of insert mounting seat 13 14A Screw hole 15, 16 Wall surface of insert mounting seat 13 18 Clamp screw 19 Contact surface 19A, 19B Contact surface portion 20 Abutted part A Acute corner B B Obtuse corner C Insert center line L Insert side imaginary straight line M Mounting seat side imaginary straight line P Insert side imaginary plane Q Mounting seat side imaginary plane O Tool axis 11 axis T Tool rotation direction

Claims (10)

A cutting insert that is detachably attached to an insert mounting seat of a cutting edge exchangeable cutting tool,
A polygonal plate-like insert body having a pair of polygonal surfaces and a plurality of side surfaces arranged around the polygonal surfaces,
A cutting edge is formed on the side ridge of the polygonal surface,
The insert body is a reverse-inverted symmetrical shape with respect to the pair of polygonal surfaces,
The pair of polygonal surfaces is a seating surface on which the other polygonal surface is seated on the bottom surface of the insert mounting seat when one of the polygonal surfaces is a rake face,
The pair of polygonal surfaces are each formed with a pair of contact surfaces disposed so as to be located on the pair of insert-side virtual planes,
The pair of abutting surfaces are formed on the pair of abutting surfaces formed on the bottom surface of the insert mounting seat when the polygonal surface on which the pair of abutting surfaces are formed is the seating surface. Each can be contacted,
In the insert body, a mounting hole is formed around an insert center line connecting the centers of the pair of polygonal surfaces,
The pair of insert-side virtual planes includes one insert-side virtual straight line that is orthogonal to the insert center line in each of the pair of polygonal surfaces, and the insert side is viewed from a direction along the insert-side virtual straight line. It is arranged in the direction that intersects each other in an X shape with the virtual straight line as the intersection,
Among the side surfaces of the insert body, the one side surface with respect to one polygonal surface facing one direction out of two directions in which the insert-side virtual straight line of the pair of contact surfaces extends, The cutting insert characterized by the contact part which can contact | abut to the to-be-contacted part formed in one wall surface rising with respect to the bottom face of the said insert mounting seat. The insert body has a shape that is 180 ° rotationally symmetric with respect to the insert center line,
The insert body is rotated 180 ° around the insert center line on the other side surface with respect to one polygonal surface facing the other direction of the two directions in which the insert-side virtual straight line extends. The cutting insert according to claim 1, wherein another contact portion that can contact the contacted portion when formed is formed. Each of the polygonal surfaces of the insert body has a rectangular shape,
The insert body has a pair of long side surfaces arranged on opposite sides and a pair of short side surfaces arranged on opposite sides,
A main cutting edge is formed on each of the side ridges intersecting each long side surface of each polygonal surface,
3. The insert-side imaginary straight line extends in a direction intersecting with the long side surface when viewed from a direction facing the polygonal surface, and the contact portion is formed on the long side surface. Cutting insert as described in.   The main cutting edge, as viewed from the direction facing the long side surface, gradually moves toward the opposite polygon side in the insert center line direction from one corner portion of the polygon surface to the other corner portion. The cutting insert according to claim 3, wherein the cutting insert is inclined as follows. The polygonal surface of the insert body has a parallelogram shape having a pair of obtuse corners and a pair of acute corners,
A corner blade connected to the main cutting edge is formed at the acute corner portion of each polygonal surface,
Sub-cutting blades connected to the corner blades are respectively formed on the side of the acute corner portion of the side ridge portion intersecting the short side surfaces of the polygonal surfaces,
The cutting insert according to claim 3 or 4, wherein the insert-side imaginary straight line extends in a direction orthogonal to the long side surface when viewed from a direction facing the polygonal surface.   The main cutting edge, as viewed from the direction facing the long side surface, gradually increases in the direction of the insert center line from the acute corner portion of the polygonal surface having a parallelogram shape toward the obtuse corner portion. The cutting insert according to claim 5, wherein the cutting insert is inclined so as to face the square surface side.    The pair of abutting surfaces are formed on the inner side of the polygonal surface at a distance from the side ridges, and are defined in any one of claims 1 to 6. Cutting insert.   The pair of contact surfaces each include a plurality of contact surface portions spaced apart from each other and disposed along the pair of insert-side virtual planes. The cutting insert according to claim 1.   8. The cutting insert according to claim 1, wherein each of the pair of contact surfaces is continuous along the pair of insert-side virtual planes. A cutting edge exchangeable cutting tool,
A tool body rotated about an axis,
The cutting insert according to any one of claims 1 to 9, which is detachably attached to the outer periphery of the tool body,
In the tool body, one or more insert mounting seats are formed with the one wall surface rising in the tool rotation direction with respect to the bottom surface with the bottom surface facing the tool rotation direction,
On the bottom surface of the insert mounting seat, a pair of contacted surfaces that come into contact with the pair of contact surfaces of the polygonal surface as the seating surface of the cutting insert are respectively a pair of mounting seat side virtual surfaces. Formed along a plane,
The pair of mounting seat side virtual planes includes one mounting seat side virtual straight line that extends on the bottom surface and intersects the one wall surface, and faces the one wall surface along the mounting seat side virtual straight line. As seen from the above, the pair of insert-side virtual planes of the polygonal surface as the seating surface intersect with each other in an X-shape complementary to the X-shape formed when viewed in a direction along the insert-side virtual straight line. Arranged in the direction to
A blade edge exchangeable cutting tool, wherein a contacted portion that contacts the contact portion of the cutting insert is formed on the one wall surface of the insert mounting seat.

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