JP6318558B2 - Cutting insert and replaceable edge drilling tool - Google Patents

Description

  The present invention is a cutting insert that is detachably attached to an insert mounting seat formed on a tool body of a blade-tip-exchange-type hole machining tool, and that forms a machining hole by cutting a pilot hole provided in advance in a work material, Further, the present invention relates to an edge-exchange-type drilling tool to which such a cutting insert is attached.

  As such a cutting insert and a blade-tip-exchange-type drilling tool, Patent Document 1 has a polygonal flat plate shape, and has two polygonal surfaces and side surfaces orthogonal to these polygonal surfaces. The square surface is formed with a cutting edge extending from the corner of the polygonal surface along the side ridge, and a breaker groove extending along the inside of the cutting blade and recessed from the polygonal surface. A cutting insert having an inclined surface that recedes as it goes away from the corner when viewed from the direction facing the surface, and a cutting edge is formed at the intersecting ridge line portion between the inclined surface and the side surface, and such a cutting insert, One polygonal surface is a rake face on the tool body rotated about the axis and faces the tool rotation direction, and one corner of the polygonal surface protrudes toward the outer peripheral side of the tool body and extends from the corner. Cutting edge is attached so that the cutting edge extends to the inner circumference. Shikiana machining tool has been proposed.

  More specifically, the cutting insert described in Patent Document 1 has a square plate shape, and breaker grooves are formed in all eight corners of the two square surfaces when viewed from the direction facing the polygonal surface. The polygonal surface is formed with a rib portion that extends from the central portion toward each side ridge portion and divides the breaker groove into corner portions. In such a cutting insert, two polygonal surfaces are mutually negative, and when one is a rake surface, the other is a seating surface, and the side that is a flank is perpendicular to the polygonal surface that is a rake surface. Even when this type of cutting insert is attached to a tool with a replaceable cutting edge, the radial rake angle and axial rake angle of the cutting edge used for cutting can be made regular by the inclined surface of the breaker groove. The cutting resistance can be reduced by the improvement.

JP 2007-283466 A

  However, in the cutting insert described in Patent Document 1, breaker grooves are formed at all corners as described above, and the cutting surface is a seating surface opposite to the polygonal surface that is the rake face. Even in the square surface, a breaker groove is formed in a corner portion that is opposed to the corner portion of the rake face that protrudes toward the outer peripheral side of the tool body. For this reason, an overhanging portion is formed by a breaker groove on the back side of the cutting blade used for cutting, and the mounting rigidity of the cutting insert with respect to the cutting load acting on the cutting blade is impaired. Since chatter vibrations are generated during machining, it is impossible to increase the feed rate, leading to a reduction in machining efficiency, and in some cases, the cutting insert may be broken and the insert life may be consumed.

  The present invention has been made under such a background. In a cutting insert in which two polygonal surfaces are mutually raked and one is a raked surface, the other is a raked surface. Even if a concave chip breaker is formed at the corner of the polygonal surface, it is possible to improve the machining efficiency and extend the insert life without impairing the mounting rigidity against the cutting load acting on the cutting blade. An object of the present invention is to provide a cutting insert and to provide an edge-changing hole drilling tool to which such a cutting insert is attached.

In order to solve the above problems and achieve such an object, the cutting insert of the present invention has a polygonal plate-like insert body, and the insert body has a regular polygon with an even number of corner portions. A first polygonal surface, a second polygonal surface facing away from the first polygonal surface, and a relative relationship between the first and second polygonal surfaces (which are desired) A plurality of side surfaces extending between the side ridges, and when the first and second polygonal surfaces are rake faces, the other polygonal surface is the seating surface. Of the first and second corner portions adjacent to each other in the circumferential direction of the first polygonal surface, a concave first chip breaker is formed in the first corner portion. A first cutting edge is formed at the intersecting ridge line portion between the bottom surface of the chip breaker and the side surface, and the second The corner portion is formed in a planar shape, and the first corner portion among the third and fourth corner portions of the second polygonal surface respectively opposed to the first and second corner portions. The third corner portion opposite to the second corner portion is formed in a planar shape, and a concave second chip breaker is formed in the fourth corner portion opposite to the second corner portion. A second cutting edge is formed at the intersection ridge line portion between the bottom surface of the chip breaker and the side surface, and the first and second polygonal surfaces intersect the side surface perpendicularly at the second and third corner portions. The corner portions of the first polygonal surface are alternately used as the first and second corner portions in the circumferential direction of the first polygonal surface and the second polygonal surface. The corner portion is opposite to the first and second corner portions, and the corner portion is opposite to the second polygonal surface. Circumferential direction to the alternating third, characterized in that there is a fourth corner portion.

  The cutting edge replaceable drilling tool of the present invention comprises such a cutting insert and a tool body, and the cutting insert is attached to and detached from the outer periphery of the tip of the tool body rotated about the axis in the tool rotation direction. An insert mounting seat that can be mounted is formed, and the cutting insert on the insert mounting seat has one of the first and second polygonal surfaces as the rake face in the tool rotation direction. The first corner portion or the fourth corner portion of the one polygonal surface is directed toward the outer peripheral side of the tip end of the tool body, and the one first corner portion or the fourth corner portion One of the first cutting blade or the second cutting blade formed in the corner portion is attached so as to extend to the inner peripheral side of the tool body.

  Therefore, in the cutting insert having the above-described configuration, the planar shape of the second polygonal surface with respect to the first corner portion where the first chip breaker having the first polygonal surface is formed on the front and back of the insert body. The third corner portion of the second polygonal surface is opposed to the fourth corner portion on which the second chip breaker having the second polygonal surface is formed. The two corner portions are opposite to each other. For this reason, when using the 1st corner part in which the 1st cutting edge was formed for cutting, the planar 3rd corner part of the 2nd polygonal surface of the back side adheres to the bottom of an insert mounting seat. In addition, when the fourth corner portion having the second cutting edge is used for cutting, the planar second corner portion of the first polygonal surface on the back surface is in close contact with the bottom surface of the insert mounting seat. Therefore, the mounting rigidity of the insert body can be sufficiently secured, and chatter vibration and breakage of the insert body can be prevented.

Furthermore, in the present invention, the insert body, the number of the corner portions be formed in the even of a regular polygon-shaped, the corners of the first polygonal surface, circumference of the first polygonal surface The first and second corner portions are alternately arranged in the direction, and the second polygonal corner portion is opposite to the first and second corner portions, respectively. The third and fourth corner portions are alternately arranged in the circumferential direction of the rectangular surface, and the first to fourth corner portions are formed in all the even number of corner portions that are four or more of the first and second polygonal surfaces. The first and second cutting edges formed at the first and fourth corner portions can be used by rotating and reversing the insert body.

  Further, in the cutting insert having the above-described configuration, the chip breaker is not formed in the second and third corner portions, and the cutting edge is not formed, so the first chip breaker intersects the first corner portion. Extending along at least one of the side ridges of the first polygonal surface, the at least one of the first polygonal surfaces as viewed from a direction facing the first polygonal surface. The second chip breaker is formed to have a length of ½ or more of one side ridge portion, and the second chip breaker is at least of the side ridge portions of the second polygonal surface intersecting the fourth corner portion. It extends along one side ridge, and is formed to have a length of ½ or more of the at least one side ridge of the second polygonal surface when viewed from the direction facing the second polygonal surface. By doing so, the bottom surface of the first and second chip breakers and the side surface are It can first be formed in the ridge portion, by increasing the effective cutting edge length of the second cutting edge to ensure a large cutting depth.

  On the other hand, the first chip breaker is formed so as to extend along the two side ridges of the first polygonal surface intersecting the first corner, and is connected to the two side ridges. The first cutting edge is formed at each of the intersecting ridge lines between the two side surfaces and the bottom surface of the first chip breaker, and the second chip breaker also intersects the fourth corner portion. Formed so as to extend along the two side ridge portions of the polygonal surface of the polygonal surface, and the cross ridge line portion between the two side surfaces connected to the two side ridge portions and the bottom surface of the second chip breaker, respectively. By forming the second cutting edge, the cutting insert can be rotated counterclockwise even when the cutting body is rotated clockwise when the tool body rotates clockwise when viewed from the axial front end side. Also attached to the drilling tool Can, it is possible to use as a cutting insert so-called freely without.

  Further, when two first and second cutting edges are formed in the first and fourth corner portions, respectively, the first corner portion includes the first corner portion on the first corner portion side. Than the angle of intersection of the two side ridges of the first polygonal surface that intersects the first corner when viewed from the direction facing the first polygonal surface. A first auxiliary cutting edge extending in a direction intersecting at a large angle is formed, and the fourth corner portion is also formed at the end of the second cutting blade on the fourth corner portion side. A second extending in a direction intersecting at an angle larger than the intersection angle of the two side ridge portions of the second polygon surface intersecting the fourth corner portion when viewed from the direction facing the two polygon surfaces. As described above, one first cutting edge or second cutting edge extends to the inner peripheral side of the tool body. When the cutting insert is attached to the edge-changing hole drilling tool as described above, the other one of the first cutting edge or the auxiliary cutting edge at the end of the fourth cutting edge is parallel to the axis when viewed from the tool rotation direction. The surface roughness of the inner peripheral surface of the machining hole can be improved by the auxiliary cutting edge.

  Further, the bottom surface of the first chip breaker is formed so as to be gradually recessed from the first cutting edge toward the inside of the first polygonal surface, and the bottom surface of the second chip breaker is also formed by the first chip breaker. By forming it so as to be gradually recessed from the second cutting edge toward the inside of the second polygonal surface, even when it is a negative type cutting insert, the rake angle when it is attached to the edge-changing hole drilling tool is corrected. Even if it is a corner or a negative angle, the sharpness can be improved as an angle close to the positive angle side.

  As described above, according to the present invention, the mounting rigidity of the insert body to the tool body can be ensured, and chatter vibration is prevented from occurring even when the feed is increased, and highly efficient drilling is performed. In addition, it is possible to provide a long-life cutting insert by preventing breakage of the insert body.

It is a perspective view which shows one Embodiment of the cutting insert of this invention. It is the top view which looked at embodiment shown in FIG. 1 from the direction which opposes a 1st polygon surface. It is a ZZ sectional view in FIG. It is an enlarged plan view of the 1st corner part of embodiment shown in FIG. It is a top view which shows one Embodiment of the blade-tip-exchange-type drilling tool of this invention. FIG. 6 is a side view of the embodiment shown in FIG. 5. FIG. 6 is an enlarged front view of the embodiment shown in FIG. 5.

  1 to 4 show an embodiment of the cutting insert of the present invention, and FIGS. 5 to 7 show an embodiment of the cutting edge exchanging hole drilling tool of the present invention to which the cutting insert of this embodiment is attached. Is shown. The cutting insert of this embodiment has a polygonal plate-like insert body 1 formed of a hard material such as cemented carbide, and the insert body 1 is formed in a regular polygonal plate shape with an even number of corners. Specifically, it is formed in a regular hexagonal plate shape as shown in FIGS.

  Accordingly, the insert body 1 has a first polygonal surface 2A having a regular hexagonal shape, and a regular hexagonal shape congruent with the first polygonal surface 2A, and is opposite to the first polygonal surface 2A. A second polygonal surface 2B facing and a plurality of (six) rectangular side surfaces 3 extending between the opposite (desired) edge portions of the first and second polygonal surfaces 2A and 2B. ing. The rectangular side surface 3 has the circumferential direction of the first and second polygonal surfaces 2A and 2B as the longitudinal direction.

  At the center of the first and second polygonal surfaces 2A and 2B, a mounting hole 4 having a circular cross section that passes through the insert body 1 is opened perpendicularly to the first and second polygonal surfaces 2A and 2B. The mounting hole 4 is formed so as to gradually decrease in diameter from the opening to the first and second polygonal surfaces 2A and 2B toward the center, and to have a minimum diameter at the center. The six side surfaces 3 are parallel to the insert center line L in the direction in which the insert center line L that is the center line of the mounting hole 4 extends, and the cutting insert of this embodiment is a negative type cutting insert. Has been.

  The insert body 1 has a symmetrical shape with respect to each other with respect to three virtual lines (not shown) passing through the centers of the side surfaces 3 and orthogonal to the insert center line L, and rotated about 120 ° around the insert center line L. In some cases, the shape is 120 ° rotationally symmetric, overlapping the shape of the insert body 1 that was in the original position. Further, the first and second polygonal surfaces 2 </ b> A and 2 </ b> B are formed in a planar shape perpendicular to the insert center line L in the vicinity of the opening of the attachment hole 4.

  The six corner portions of the first polygonal surface 2A are first and second corner portions A and B alternately in the circumferential direction of the first polygonal surface 2A. In addition, the six corner portions of the second polygonal surface 2B are alternately formed as a third corner portion C and a fourth corner portion D in the circumferential direction of the second polygonal surface 2B. Accordingly, the first polygonal surface 2A has three first and second corner portions A and B, respectively, and the second polygonal surface 2B has three third and fourth corners. Corner portions C and D are provided.

  Further, the three first corner portions A of the first polygonal surface 2A and the three third corner portions C of the second polygonal surface 2B are opposed to each other in the insert center line L direction. . That is, the tips of the first corner portion A and the third corner portion C are located on the intersecting ridge line portions of the common side surfaces 3. Accordingly, the remaining three second corner portions B of the first polygonal surface 2A are respectively opposed to the remaining three fourth corner portions D of the second polygonal surface 2B in the direction of the insert center line L. ing.

The first corner portion A is formed with a concave first chip breaker 5A, and the fourth corner portion D is also formed with a concave second chip breaker 5B, while the second corner portion A is formed. The part B and the third corner part C are formed in a planar shape. The three planar second corner portions B of the first polygonal surface 2A are located on one plane perpendicular to the insert center line L, and the three planar second corners B of the second polygonal surface 2B. The third corner portion C is also located on another plane perpendicular to the insert center line L. In the present embodiment, the second corner portion B is a flat surface around the opening portion of the mounting hole 4 in the first polygonal surface 2A, and the third corner portion C is the second polygonal surface. 2B , the first and second polygonal surfaces 2A, 2B are side surfaces 3 in the flat second and third corner portions B, C. Intersects vertically .

  The first and second chip breakers 5A and 5B are provided in the first polygonal surface 2A and the second corner portion B around the mounting hole 4 and the second polygonal surface. It is formed so as to be recessed with respect to the periphery of the opening of the mounting hole 4 of 2B and the third corner C. As described above, the insert body 1 has a reverse-inverted symmetrical shape with respect to a straight line passing through the center of the side surface 3 and perpendicular to the insert center line L, and has a 120 ° rotationally symmetrical shape around the insert center line L. The total of the first and second chip breakers 5A and 5B are the same shape and size.

  The first and second chip breakers 5A and 5B are at least one side of the side ridge portions of the first and second polygonal surfaces 2A and 2B that intersect the first and fourth corner portions A and D. A bottom surface 5a which extends along the ridge and is formed so as to be gradually recessed toward the inside of the first and second polygonal surfaces 2A and 2B intersecting the side surface 3, and is flush with the bottom surface 5a. The first and second polygonal surfaces 2A and 2B, which are flat surfaces, are provided with second and third corner portions B and C and a wall surface 5b which is cut out toward the periphery of the opening of the mounting hole 4. The first and second chip breakers 5A and 5B include the wall surface 5b, and the at least one of the chip breakers 5A and 5B extends from the direction facing the first and second polygonal surfaces 2A and 2B, respectively. It is formed over a length of ½ or more of the length of one side ridge.

  The first cutting edge 6A is formed at the intersection ridge line portion between the bottom surface 5a and the side surface 3 of the first chip breaker 5A, and the second cutting edge is formed at the intersection ridge line portion between the bottom surface 5a and the side surface 3 of the second chip breaker 5B. Each blade 6B is formed. Here, the bottom surface 5a has a constant inclination angle in the direction perpendicular to the side surface 3 from the first and second cutting edges 6A and 6B toward the inside of the first and second polygonal surfaces 2A and 2B. It is recessed in the direction of the insert center line L, and has a constant inclination in the direction away from the protruding ends of the first and fourth corner portions A and D along the side ridge portions of the first and second polygonal surfaces 2A and 2B. The first and second cutting edges 6A and 6B are also formed in a straight line that is recessed at a constant inclination angle as the distance from the projecting ends of the first and fourth corner portions A and D is increased. Is done.

  Further, the wall surface 5b is a side away from the inner edges of the first and second polygonal surfaces 2A and 2B of the bottom surface 5a thus inclined and the protruding ends of the first and fourth corner portions A and D. From the edges of the first and second polygonal surfaces 2A and 2B, rising in the circumferential direction from the edge of the first and second polygonal surfaces 2A, 2B, and the second portion of the mounting hole 4 and the second The third corner portions B and C are formed so as to be cut off with a space therebetween. In the first and second cutting edges 6A and 6B, the positions of the first and fourth corner portions A and D that protrude most in the insert center line L direction are in the insert center line L direction. The first and second polygonal surfaces 2A and 2B are provided around the opening of the mounting hole 4 and on the plane where the second and third corner portions B and C are located. Moreover, honing is given to the 1st, 2nd cutting blade 6A, 6B.

  Further, in the present embodiment, the first and second chip breakers 5A and 5B have two sides of the first and second polygonal surfaces 2A and 2B that intersect the first and fourth corner portions A and D, respectively. It extends along the ridge, and when viewed from the direction facing the first and second polygonal surfaces 2A and 2B, it forms a V shape extending along these two side ridges, and the first and second It is formed symmetrically with respect to a plane including the bisectors of the four corner portions A and D. Accordingly, the first and second cutting edges 6A and 6B are also formed two by two symmetrically with respect to the plane including the bisector for each of the first and fourth corner portions A and D.

  Furthermore, as described above, the first and second chip breakers 5A and 5B have a length of 1/2 or more of the side ridges of the first and second polygonal surfaces 2A and 2B from which the chip breakers 5A and 5B extend. Accordingly, in the perspective view seen from the direction facing the first and second polygonal surfaces 2A and 2B, the end portions of the first and second chip breakers 5A and 5B on the front and back sides are mutually connected. Will overlap. In the present embodiment, as shown in FIG. 2 in the perspective view, the wall surfaces 5b of the end portions of the first and second chip breakers 5A and 5B rising in the circumferential direction of the first and second polygonal surfaces 2A and 2B. The first and second cutting edges 6A and 6B overlap each other so as to be substantially continuous at the midpoint between the first and second polygonal surfaces 2A and 2B.

  Furthermore, on the side of the intersecting ridgeline part between the side surfaces 3 adjacent to each other in the circumferential direction, the side surface 3 bends at an obtuse angle close to a flat angle with respect to the side surface 3, and more than the intersection angle (120 °) formed by these side surfaces 3. A chamfer plane 3A extending in a direction intersecting each other at a slightly large angle is formed with a small constant width in the circumferential direction of the first and second polygonal surfaces 2A and 2B. Further, in the intersecting ridge line portion of the side surface 3 between these chamfered planes 3A, between the protruding ends of the first and third corner portions A and C opposed to the insert center line L direction, the second and second 4 is a convex curved surface having a cross-section perpendicular to the insert center line L that is narrower than the chamfered plane 3A that forms a convex curve such as an arc having a small radius of curvature so as to extend between the protruding ends of the four corner portions B and D. 3B is formed in contact with the chamfered plane 3A.

  Accordingly, the first and second cutting edges 6A, 6B on the first and fourth corner portions A, D side where the chamfered plane 3A intersects the bottom surfaces 5a of the first and second chip breakers 5A, 5B. The first and second polygonal surfaces intersecting the first and fourth corner portions A and D when viewed from the direction facing the first and second polygonal surfaces 2A and 2B. A secondary cutting edge extending in a direction intersecting at an angle larger than the crossing angle (120 °) of the side edges of 2A and 2B is formed. Among these, the sub cutting edge formed at the end of the first cutting edge 6A is the first sub cutting edge 7A, and the sub cutting edge formed at the end of the second cutting edge 6B is the second sub cutting edge. The auxiliary cutting edge 7B is used.

  The cutting insert of such embodiment is attached to the tool main body 11 as shown in FIGS. 5-7, and comprises one Embodiment of the blade-tip-exchange-type drilling tool of this invention. The tool body 11 is formed of a metal material such as steel and has a multi-stage cylindrical shape centering on the axis O, and the rear end portion (the upper end portion in FIGS. 5 and 6) is a spindle of a machine tool such as a machining center. The tip portion (the lower portion in FIGS. 5 and 6) is the blade portion 13 to which the cutting insert of the above embodiment is attached. In such a blade-tip-exchange-type drilling tool, the tool body 11 is rotated in the tool rotation direction T around the axis O, and is sent to the tip side in the axis O direction, so that a prepared hole formed in the work material is formed in advance. A hole is drilled to a predetermined inner diameter by the cutting insert.

  The blade portion 13 has the largest outer diameter in the tool main body 11, and a plurality of chip pockets 14 are formed on the outer periphery thereof at intervals in the circumferential direction. Are formed with respective insert mounting seats 15 to which the insert body 1 of the cutting insert is detachably mounted. The tip pocket 14 has a V-shape that gradually becomes wider as it goes from the outer peripheral side of the tool body 11 toward the distal end side, and a V-shape that gradually becomes wider as it goes from the distal end side of the tool body 11 toward the outer peripheral side. The insert mounting seat 15 is formed as a recess opening in the tip pocket 14 at a corner on the outer peripheral side of the tip of the wall surface of the tip pocket 14 facing the tool rotation direction T. ing. In the tool body 11, a coolant hole 11A is formed along the axis O from the shank portion 12 toward the blade portion 13, and the coolant hole 11A branches radially at the blade portion 13 to each chip pocket 14. Is opened.

  The insert mounting seat 15 has a regular hexagonal shape that is substantially congruent with the first and second polygonal surfaces 2A, 2B, and has a one-step recessed tool rotation direction T from the wall surface of the tip pocket 14 to the rear side in the tool rotation direction T. There is provided a mounting seat bottom surface 15a facing and a mounting seat wall surface 15b facing the tip side from the outer peripheral side of the rear end of the tool body 11 of the mounting seat bottom surface 15a to the wall surface. The mounting seat bottom surface 15a is slightly inclined toward the tool rotation direction T as it goes toward the rear end side of the tool body 11, and the above-mentioned mounting seat bottom surface 15a has the above-mentioned in order to attach the insert body 1 to the central portion. A screw hole (not shown) into which the clamp screw 16 inserted through the attachment hole 4 is screwed is formed. The mounting seat wall surface 15b is inclined so as to cross the outer peripheral surface of the blade portion 13 and toward the rear end side toward the inner peripheral side, and extends in a direction orthogonal to the mounting seat bottom surface 15a.

  Furthermore, a concave groove 17 is formed on the inner peripheral side of the insert mounting seat 15 so as to open to a wall surface facing the outer peripheral side of the tool body 11 of the insert mounting seat 15 and extend to the inner peripheral side. The adjustment wedge 18 is inserted, and the adjustment screw 19 inserted from the front end side of the tool body 11 is screwed into the tool body 11 to be attached. The adjustment wedge 18 has a side surface facing the outer peripheral side of the tool body 11 adjusted by adjusting the screwing amount of the adjustment screw 19, and the insert body attached to the insert mounting seat 15 by this side surface. 1 is pressed so that the radial position can be finely adjusted.

  On the insert mounting seat 15, the insert body 1 has one polygonal surface which is the rake face of the first and second polygonal surfaces 2 </ b> A and 2 </ b> B (the first polygonal surface in FIGS. 5 to 7 is the first one). The polygonal surface 2A) is directed in the tool rotation direction T, and one first corner portion A of the first polygonal surface 2A, which is one of the polygonal surfaces, is directed toward the outer peripheral side of the tip of the tool body 11, and this One first cutting edge 6A formed in one first corner portion A is attached by the clamp screw 16 so as to extend to the inner peripheral side of the tool body 11. In the present embodiment, the first cutting edge extending in the clockwise direction when viewed from the one first corner portion A facing the outer peripheral side of the tool body 11 in the direction facing the first polygonal surface 2A. 6A extends toward the distal end side toward the inner peripheral side of the tool body 11 as the first cutting edge 6A.

  Therefore, in the insert main body 1 attached in this way, the other polygonal surface (the second polygonal surface 2B in FIGS. 5 to 7) which is the seating surface of the first and second polygonal surfaces 2A and 2B. ) Is directed to the rear side in the tool rotation direction T and seated on the mounting seat bottom surface 15a of the insert mounting seat 15, and the one first cutting edge is viewed from the direction facing the first polygonal surface 2A. From the side surface 3 connected to the blade 6A, one side surface 3 placed in the counterclockwise direction is directed to the outer peripheral side of the rear end of the tool body 11 and brought into contact with the mounting seat wall surface 15b. The side surface 3 is directed toward the inner peripheral side of the tool body 11 and is brought into contact with the side surface of the adjustment wedge 18. In addition, between the side surface 3 located on the opposite side to the side surface 3 connected to the one first cutting edge 6A, and the wall surface of the insert mounting seat 15 between the mounting seat wall surface 15b and the side surface of the adjustment wedge 18. Has a small gap.

  Further, since the mounting seat bottom surface 15a of the insert mounting seat 15 is inclined as described above, the first polygonal surface 2A, which is a rake face, also moves in the tool rotation direction T toward the rear end side of the tool body 11. It is tilted towards a negative axial rake angle. Furthermore, in the present embodiment, the radial rake angle of the first polygonal surface 2A that is a rake face as shown in FIG. 7 is also set to the negative angle side.

  Furthermore, another one first cutting edge 6A extending from the one first corner portion A directed toward the outer peripheral side of the front end of the tool body 11 to the rear end side of the tool body 11, and the other one first The side surface 3 of the insert main body 1 connected to one cutting edge 6A is inclined so as to go to the inner peripheral side of the tool main body 11 as it goes to the rear end side. However, the first auxiliary cutting edge 7A formed at the end of the one other first cutting edge 6A on the one first corner portion A side has the axis O in the rotation locus around the axis O. Is substantially positioned on a cylindrical surface centered at.

  As described above, the cutting edge exchanging drilling tool according to the embodiment of the present invention in which the cutting insert having the above-described configuration is attached to the tool body 11 is sent to the front end side in the axis O direction while being rotated around the axis O as described above. Thus, the one first cutting edge 6A of the cutting insert attached to the blade portion 13 cuts the inner peripheral surface of the prepared hole of the work material to form a processed hole having a predetermined inner diameter. However, the allowance from the prepared hole to the machining hole is within the range of the cutting edge length of the one first cutting edge 6A in the radial direction with respect to the axis O of the tool body 11.

  And in the cutting insert attached as mentioned above, one 1st cutting edge used for cutting of the 1st polygon surface (one polygon surface) 2A made into the rake face of the insert main body 1 In contrast to the first corner portion A on which 6A is formed, a third corner portion having a planar shape perpendicular to the insert center line L in the second polygonal surface (the other polygonal surface) 2B serving as a seating surface. C comes into close contact with the mounting seat bottom surface 15a of the insert mounting seat 15 in the direction of the insert center line L.

  For this reason, the cutting load acting on the one first cutting edge 6A formed on the concave first chip breaker 5A at the time of drilling is received from the planar third corner C by the mounting seat bottom surface 15a. Thus, the mounting rigidity of the insert body 1 can be sufficiently ensured. Therefore, chatter vibration is generated during drilling due to insufficient rigidity, or the cutting load acts on the fourth corner portion D where the second chip breaker 5B is formed on the second polygonal surface 2B which is the seating surface. By doing so, it is possible to prevent the insert body 1 from being broken.

  The same applies to the case where the second polygonal surface 2B is one of the polygonal surfaces that is the rake face. That is, with respect to the fourth corner portion D where the concave second chip breaker 5B in which the second cutting edge 6B of the second polygonal surface 2B is formed, the other corner portion D is set as the seating surface. Since the planar second corner portion B of the first polygonal surface 2A, which is a polygonal surface, faces each other, the second corner portion B can secure the mounting rigidity of the insert body 1. . Therefore, according to the cutting insert having the above-described configuration and the cutting edge exchanging drilling tool to which the cutting insert is attached, the chatter vibration is prevented as described above, so that the feed can be increased to perform highly efficient drilling. In addition, the insert life can be extended and stable and efficient drilling can be performed over a long period of time.

  Moreover, in the cutting insert of this embodiment, the insert main body 1 is formed in the regular polygon plate shape which has an even number of corner parts AD. In the first polygonal surface 2A, even-numbered corner portions A and B are alternately formed in the circumferential direction as first and second corner portions A and B, and in the second polygonal surface 2B, the first The corner portions respectively facing the first and second corner portions A and B of the polygonal surface 2A are alternately set as third and fourth corner portions C and D in the circumferential direction.

  Therefore, when one first cutting edge 6A used for drilling the first polygonal surface 2A, which is a rake face, has reached the end of its life, the insert body 1 is rotated around the insert center line L and reattached. The other first cutting edge 6A is used for drilling, and when all the first cutting edges 6A on the first polygonal surface 2A have reached the end of their life, the insert body 1 is inverted and reattached. Thus, the second cutting edge 6B can be used for drilling with the second polygonal surface 2B as a rake face. For this reason, the insert body 1 can be effectively used while preventing chatter vibration and breakage as described above.

  In particular, in the present embodiment, in the first and second polygonal surfaces 2A and 2B of the insert body 1 thus formed into an even regular polygonal plate shape, the planar second and third corner portions B are planar. , C is flush with the planar portion around the opening of the attachment hole 4 of each polygonal surface 2A, 2B. For this reason, in the other polygonal surface used as the seating surface, a flat surface that is flush with the entire surface can be brought into close contact with the mounting seat bottom surface 15a, and the mounting rigidity of the insert body 1 can be secured more reliably. can do.

  In the present embodiment, the first chip breaker 5A extends along at least one side ridge portion of the side ridge portions of the first polygonal surface 2A intersecting the first corner portion A. The first polygonal surface 2A is formed to have a length of ½ or more of the at least one side ridge portion when viewed from the direction facing the first polygonal surface 2A. Furthermore, the second chip breaker 5B also extends along at least one side ridge portion of the side ridge portions of the second polygonal surface 2B intersecting the fourth corner portion D, so that the second polygon The second polygonal surface 2B is formed to have a length of ½ or more of the at least one side ridge portion as viewed from the direction facing the surface 2B.

  That is, the second and third corner portions B and C in which the first and second chip breakers 5A and 5B are not formed are formed in a planar shape around the protruding end, and the other polygonal shape. Since it is only necessary to be able to receive the cutting load acting on the first and second cutting edges 6A and 6B of the first and fourth corner portions A and D facing each other when the seating surface is used as the seating surface, By forming the first and second chip breakers 5A and 5B to have the above-mentioned lengths while leaving the planar portion to the minimum necessary, the cross-ridge line portion between the bottom surface 5a and the side surface 3 is formed. The effective cutting edge length of the first and second cutting blades 6A and 6B can be increased, and a large cutting amount can be ensured while maintaining sufficient mounting rigidity.

  Moreover, in the present embodiment, the first chip breaker 5A is formed so as to extend along the two side ridges of the first polygonal surface 2A intersecting the first corner A, The first cutting edge 6A is formed on each of the intersecting ridge lines between the side surface 3 of the two insert main bodies 1 connected to the two side ridges and the bottom surface 5a of the first chip breaker 5A, and the second chip. The breaker 5B is also formed so as to extend along two side ridges of the second polygonal surface 2B intersecting the fourth corner portion D, and two side surfaces 3 connected to these two side ridges, The second cutting edge 6B is formed on each of the intersecting ridge lines with the bottom surface 5a of the second chip breaker 5B.

  That is, the first and second chip breakers 5A and 5B and the first and second cutting edges 6A and 6B are symmetrical with respect to the plane including the bisector of the first and fourth corner portions A and D. Since it is formed, the cutting insert of this embodiment is a cutting edge replaceable drilling tool in which the tool body 11 rotates counterclockwise around the axis O as shown in FIG. The first and second cutting blades 6A and 6B are at the tip of the tool body 11 even when they are attached, or when the tool body 11 is attached to a blade edge exchanging hole drilling tool that rotates in the clockwise direction. It can arrange | position so that it may extend from an outer periphery to an inner peripheral side, and can drill a hole as a so-called unintentional cutting insert.

  Furthermore, in the cutting insert of the present embodiment, in addition to forming the first and second cutting edges 6A and 6B in the first and fourth corner portions A and D, respectively, The corner portion A includes a first intersection that intersects the first corner portion A when viewed from the direction facing the first polygonal surface 2A at the end of the first cutting edge 6A on the first corner portion A side. The first sub cutting edge 7A extending in a direction intersecting at an angle larger than the intersecting angle of the two side ridge portions of one polygonal surface 2A is formed, and the fourth corner portion D is also formed in the fourth corner portion D. Two corners of the second polygonal surface 2B intersecting the fourth corner portion D when viewed from the direction facing the second polygonal surface 2B at the end of the second cutting edge 6B on the corner portion D side Second sub-cutting blades 7B extending in a direction intersecting at an angle larger than the intersection angle of the side ridges are formed.

  And in the blade-tip-exchange-type drilling tool of the above-described embodiment to which this cutting insert is attached, the tool body 11 extends from the one first corner portion A directed toward the outer periphery of the tip to the rear end side of the tool body 11. The first auxiliary cutting edge 7A formed at the tip end of the first cutting edge 6A is substantially positioned on a cylindrical surface centering on the axis O in the rotation locus around the axis O. The surface roughness can be improved by smoothly finishing the inner peripheral surface of the processed hole by the first auxiliary cutting edge 7A. This is the same even when the insert body 1 is attached with the second polygonal surface 2B facing the tool rotation direction T and the second cutting edge 6B is used for drilling.

  Furthermore, in the cutting insert of the present embodiment, the bottom surface 5a of the first chip breaker 5A is formed so as to be gradually recessed from the first cutting edge 6A toward the inside of the first polygonal surface 2A, and The bottom surface 5a of the second chip breaker 5B is also formed so as to be gradually recessed from the second cutting edge 6B toward the inside of the second polygonal surface 2B, and the planar second and third corner portions B are formed. , C, the first and second polygonal surfaces 2A and 2B are negative type cutting inserts perpendicular to the side surface 3, but the first and second cutting edges 6A and 6B The side surface 3 can be made to intersect at an acute angle.

  For this reason, the first polygonal surface 2A, which is a rake face, is inclined toward the tool rotation direction T as it goes to the rear end side of the tool body 11 like the cutting edge exchanging hole drilling tool of the present embodiment. Even if a negative axial rake angle is given by the above, the actual axial rake angle of the first cutting edge 6A used for drilling is a positive angle or an angle close to the positive side even if it is a negative angle. Therefore, the cutting resistance can be improved and the cutting resistance can be reduced. This also applies to the case where the insert main body 1 is attached with the second polygonal surface 2B facing the tool rotation direction T and the second cutting edge 6B is used for drilling.

  In the cutting insert of the present embodiment, the bottom surfaces 5a of the first and second chip breakers 5A and 5B are connected to the first and second polygonal surfaces 2A from the projecting ends of the first and fourth corner portions A and D, respectively. 2B, the first and second cutting edges 6A and 6B are also first and fourth corner portions A and D, respectively. It is formed in the shape of a straight line that is recessed at a constant inclination angle as it is separated from the protruding end. For this reason, even if the radial rake angles of the first and second polygonal surfaces 2A and 2B, which are rake surfaces as described above, are set to the negative angle side, the first and second holes used for drilling are used. The actual radial rake angle of the cutting blades 6A and 6B can be a positive angle or an angle close to the positive angle side even if it is a negative angle, and the sharpness can be improved.

DESCRIPTION OF SYMBOLS 1 Insert body 2A 1st polygonal surface 2B 2nd polygonal surface 3 Side surface 3A Chamfering plane 3B Convex-curved surface 4 Mounting hole 5A 1st chip breaker 5B 2nd chip breaker 5a 1st, 2nd chip breaker 5A 5B bottom surface 5b first and second chip breakers 5A, 5B wall surface 6A first cutting blade 6B second cutting blade 7A first sub cutting blade 7B second sub cutting blade 11 tool body 15 insert mounting Seat 15a Mounting seat bottom surface 15b Mounting seat wall surface 16 Clamp screw 18 Adjustment wedge AD First to fourth corners L Insert center line O Tool body axis 11 T Tool rotation direction

Claims (6)

It has a polygonal plate-like insert body,
The insert body is formed in a regular polygonal plate shape having an even number of corner portions, and includes a first polygonal surface and a second polygonal surface facing away from the first polygonal surface. A plurality of side surfaces extending between the opposite side ridge portions of the first and second polygonal surfaces,
The first and second polygonal surfaces, when one polygonal surface is a rake face, the other polygonal surface is a seating surface,
Of the first and second corner portions adjacent to each other in the circumferential direction of the first polygonal surface, a concave first chip breaker is formed in the first corner portion, and this first chip is formed. The first cutting edge is formed at the intersecting ridge line portion between the bottom surface of the breaker and the side surface, and the second corner portion is formed in a planar shape,
Of the third and fourth corner portions of the second polygonal surface respectively facing the first and second corner portions, the third corner portion facing the first corner portion is planar. In addition, a concave second chip breaker is formed in the fourth corner portion opposite to the second corner portion, and an intersecting ridge line between the bottom surface of the second chip breaker and the side surface A second cutting edge is formed on the part ,
In the second and third corner portions, the first and second polygonal surfaces intersect the side surfaces perpendicularly,
The corner portions of the first polygonal surface are alternately made the first and second corner portions in the circumferential direction of the first polygonal surface,
In the corner portion of the second polygonal surface, the corner portions facing the first and second corner portions are alternately arranged in the circumferential direction of the second polygonal surface. Cutting insert characterized by being said. The first chip breaker extends along at least one side ridge portion of the first polygon surface intersecting the first corner portion, and the first polygon surface. Is formed to have a length of ½ or more of the at least one side ridge portion of the first polygonal surface as viewed from the direction opposite to
The second chip breaker extends along at least one of the side ridges of the second polygonal surface intersecting the fourth corner portion, and the second polygonal surface 2. The cutting insert according to claim 1 , wherein the cutting insert is formed to have a length equal to or more than ½ of the at least one side ridge portion of the second polygonal surface when viewed from a direction facing the surface. The first chip breaker extends along the two side ridges of the first polygonal surface intersecting the first corner portion, and the two side surfaces connected to the two side ridges The first cutting edge is formed on each of the intersecting ridge lines with the bottom surface of the first chip breaker,
The second chip breaker extends along the two side ridges of the second polygonal surface intersecting the fourth corner portion, and the two side surfaces connected to the two side ridges 3. The cutting insert according to claim 1, wherein the second cutting edge is formed at each of the intersecting ridge lines with the bottom surface of the second chip breaker. 4. The first corner portion intersects the first corner portion at the end of the first cutting edge on the first corner portion side when viewed from the direction facing the first polygonal surface. A first auxiliary cutting edge extending in a direction intersecting at an angle larger than the intersection angle of the two side ridges of the first polygonal surface is formed,
The fourth corner portion intersects the fourth corner portion at the end of the second cutting edge on the fourth corner portion side when viewed from the direction facing the second polygonal surface. according to claim 3, wherein said second sub-cutting edge extending in a direction in which the second than the crossing angle of the two above Henryo portion of the polygonal plane cross at a large angle is formed respectively to Cutting inserts. The bottom surface of the first chip breaker is formed so as to be gradually recessed from the first cutting edge toward the inside of the first polygonal surface,
It said bottom surface of the second chip breaker, said second cutting edge said second claim 4 that claim 1, characterized in that is formed as gradually recessed toward the inside of the polygonal surface The cutting insert as described in any one of them. A cutting insert according to any one of claims 1 to 5 , and a tool body,
An insert mounting seat to which the cutting insert is detachably mounted is formed on the outer periphery of the tip of the tool body rotated in the tool rotation direction around the axis,
In the insert mounting seat, the cutting insert directs the one polygonal surface, which is the rake face, of the first and second polygonal surfaces in the tool rotation direction, and 1 of the one polygonal surface. The first corner portion or the fourth corner portion is directed toward the outer peripheral side of the tip of the tool body, and the first corner portion formed on the first corner portion or the fourth corner portion. A cutting edge exchanging type drilling tool, wherein the cutting edge or the second cutting edge is attached so as to extend to the inner peripheral side of the tool body.

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