JP2008207312A - Cutting insert - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a long-life cutting insert, which can improve a chip treatment and a reliable control of the chip flowing direction even in a case of a work profile-finishing lathe-turning treatment. <P>SOLUTION: The periphery of a corner portion C of a cutting edge 5 to be formed in an insert body 1 is formed of a cBN sintered body 9B. In the corner portion C, a chamfered portion 6 is formed along the cutting edge 5. In this chamfered portion 6 at the corner portion C, there is formed a chip breaker 10, which is equipped with a breaker bottom face 10A directed to the side of a rake face 2 of the cutting edge 5, and a breaker wall face 10B rising with respect to the breaker bottom face 10A. In the portion facing the corner portion C, the chip breaker 10 is formed at its breaker wall face 10B into either a convex face curved along a convex line formed by the corner portion C or a multiple step shape of five or more steps. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cutting insert in which a periphery of a cutting edge corner portion of an insert body is formed of a cBN sintered body, a chamfered portion is formed in the corner portion, and a chip breaker is formed in the chamfered portion. is there.

  As this type of cutting insert, for example, in Patent Document 1, cBN is applied to the cutting edge corner portion of the insert body for the purpose of cutting edge strengthening processing and good chip disposal in finish cutting of carburized quenched steel and induction-hardened steel. A chip breaker is proposed in which a sintered body is joined to form a chamfered portion, and a chip breaker having a breaker bottom surface and a breaker wall surface rising from the bottom surface of the breaker to form a concave cylindrical surface is proposed. In particular, the breaker wall surface is formed to extend in a straight line when viewed from the direction facing the bottom surface of the breaker.

Further, in Patent Document 2, this chip breaker is formed substantially symmetrically with respect to a section that bisects the corner portion, and a pair of ridge lines that are linear or concave arc-shaped are formed on the top of the breaker wall surface. What has been formed is proposed. Further, the inventors of the present invention have also proposed in Patent Document 3 that the breaker wall surface is formed so as to stand substantially vertically from the bottom surface of the breaker. In Patent Document 3, the breaker wall surface is formed on the corner. A pair of first breaker walls extending substantially linearly with a first obtuse angle across the bisector of the portion, and a second obtuse angle greater than the first obtuse angle, connected to the first breaker wall. It has also been proposed to form a pair of second breaker walls extending in a straight line.
JP-A-8-155702 International Publication No. 2005/068117 Pamphlet JP 2006-95620 A

  By the way, when trying to turn a workpiece with an uneven surface by following the unevenness, especially with a corner of such a cutting insert, the cutting edge is cut into the workpiece due to the unevenness of the workpiece surface. The cutting point to be changed changes along a corner portion having a convex curve shape. However, as described in Patent Documents 1 to 3, the breaker wall surface extends in a straight line, a two-step or four-step straight line, or even a concavely curved ridge line. In addition, since the distance between the breaker wall surface and each part of the corner part also changes along the corner part, when the part where this distance is small becomes a cutting point, the chip becomes clogged and it seems that this When a part with a large distance becomes the cutting point, the chips tend to stretch and wind around the holder, and in either case, it is difficult to achieve reliable and smooth chip disposal, which increases productivity. There was a risk of reduction. In particular, in finish turning with a low depth of cut and a small chip thickness, such a problem becomes more conspicuous because the chip extends over the chip breaker while being stretched when the distance is large.

  Further, as described in Patent Documents 2 and 3, when the breaker wall surface is constituted by a plurality of breaker walls extending in a straight line shape or a concave curve shape, chips collide with a ridge line portion where these breaker walls intersect with each other. In some cases, the breaker wall surface may be damaged at the ridge line portion, or the breaker wall surface may be worn out at an early stage. Furthermore, when the chips collide along the ridge line portion, they only come into line contact with the ridge line portion, so it becomes difficult to control the chip discharge direction and prevent the chip from being bitten. In profile turning in which the outflow direction also changes along the corner portion, there is a possibility that the machined surface that is turned may be damaged by chips.

  The present invention has been made under such a background. For turning a workpiece made of medium hardness or high hardness steel such as the hardened steel as described above, the periphery of the cutting edge corner portion is cBN-fired. Even in the case of cutting inserts with a chip breaker formed on the chamfered part formed at this corner part, and even when finishing the workpiece by finishing, the chip disposal is improved and the direction of chip flow It is an object of the present invention to provide a cutting insert that can be reliably controlled and has a long life.

  In order to solve the above problems and achieve such an object, according to the present invention, the corner portion periphery of the cutting edge formed in the insert body is formed of a cBN sintered body, A chip breaker having a chamfered portion formed along the cutting edge, and having a breaker bottom surface facing the corner portion and facing the rake face side of the cutting blade, and a breaker wall surface rising from the breaker bottom surface. The chip breaker has a convex curved shape in which the breaker wall surface is curved along a convex curve formed by the corner portion, or along the convex curve at a portion facing the corner portion. It is characterized by having a multi-step surface shape of 5 steps or more that bends and protrudes.

  In such a cutting insert, the periphery of the corner of the cutting edge to be cut into the workpiece is formed of a highly hard cBN sintered body, and further, a chamfered portion along the cutting edge is formed in this corner. In addition, it is possible to perform a reliable turning operation on a workpiece made of a steel material having a medium hardness or a high hardness, such as the above-described hardened steel, without causing any breakage in the cutting edge. The chip breaker formed so as to face the corner portion in the chamfered portion has a convex curved surface shape in which the breaker wall surface is curved along the convex curve formed by the corner portion, or a convex curve along the convex curve. Therefore, the distance between the breaker wall surface and the corner portion can be prevented from changing along the corner portion, and the breaker wall surface is entirely formed in the corner portion. It can be formed close to the cutting edge side.

  That is, if the breaker wall surface is a convex curved surface, the radius of curvature is made substantially equal to the convex curve formed by the corner portion, the distance is made substantially constant along the convex curve, and the breaker wall surface is set to the corner portion of the cutting edge. Can be approached. On the other hand, even when the breaker wall surface is multi-stepped, by increasing the number of steps to five or more steps, it is possible to approximately form a convex curved surface shape, preventing the above-mentioned distance from changing greatly, and also the breaker. A wall surface can be made to approach a corner part. Therefore, according to the cutting insert of the present invention, even if the cutting point on the corner portion of the cutting edge is changed in the profile turning, the chips are not clogged or are not stretched. Can be made to collide with the breaker wall at a distance of, especially when thin chips are generated during low-cut finishing turning, the chip can be extended by bringing the breaker wall closer to the cutting edge. It can be made to curl reliably by colliding with the wall surface of the breaker before.

  In addition, even if the flow direction of the chips changes along the corner due to this copying turning, the chips collide along the direction in which the generatrix of the convex curved surface extends when the breaker wall surface is a convex curved surface. Therefore, the impacted chips can be curled with sufficient resistance, and the curled chips can be stably discharged in a predetermined discharge direction. Since a specific ridge line portion is not formed in the direction in which the curve is curved, the ridge line portion is not lost or worn out. On the other hand, even when the breaker wall surface is a multi-step surface of five or more steps that bend and bend, it is possible to ensure a large crossing angle between the step surfaces in the bend and bend, so that breakage and wear can be prevented, Of course, when the chips come into contact with the step surface, even when they come into contact with the ridge line portion in the convex portion, the chips can be brought into contact with a certain width to be curled and the discharge direction can be controlled.

  In order to prevent the distance between the breaker wall surface and the corner portion from changing along the corner portion in this way, the curvature radius of the convex curve formed by the corner portion and the convex curved surface formed by the breaker wall surface, or the convex portion formed by the corner portion. It is desirable that the curvature radius of the curved surface and the convex curved surface in contact with the convex curved portion of the multi-step surface formed by the breaker wall surface be equal to each other. However, they do not have to be exactly the same, and the radius of curvature of the convex curved surface formed by the breaker wall surface, or the radius of curvature of the convex curved surface that touches the convex curved portion formed by the corner portion and the multi-step convex curved portion formed by the breaker wall surface The curvature radius of the convex curve formed by the corner may be approximately equal within a range of ± 20%.

  In addition, the breaker wall surface may be vertical, for example, as described in Patent Document 3, where the entire surface is perpendicular to the bottom surface of the breaker. For example, as the breaker wall rises with respect to the bottom surface of the breaker, It may be inclined so as to gradually recede in a range of 60 ° or less with respect to the direction perpendicular to the bottom surface. This prevents chips from clogging and guides the chips quickly away from the workpiece. It becomes. However, if the inclination angle of the breaker wall surface is so large that it exceeds 60 °, even if the chips collide with the breaker wall surface, sufficient resistance cannot be given, or the chip breaker gets over the chip breaker and flows out. There is a fear.

  On the other hand, the breaker wall surface is a vertical wall surface portion whose vertical side is perpendicular to the breaker bottom surface, and on the side far from the breaker bottom surface, it gradually recedes to the inside of the corner portion as it rises with respect to the breaker bottom surface. It is good also as a thing provided with the inclined wall surface part which does. By providing the vertical wall surface in this way, on the bottom surface side of the breaker, avoiding contact with the chips and preventing the resistance from becoming too large, while preventing the chips from clogging on the side away from the bottom surface of the breaker, as described above, It is possible to guide and discharge the chips so as to leave immediately.

  Furthermore, especially when the breaker wall surface has a multi-step surface shape of 5 steps or more, for example, compared to the case where the breaker wall surface is formed on a convex curved surface with a curvature radius that matches the convex curve formed by the corner portion with high accuracy. As described above, the breaker wall surface can be formed relatively easily while exhibiting substantially the same action as described above, and the time and labor for forming the chip breaker at each corner portion can be reduced. Conversely, if the cost is the same, it is possible to form such a chip breaker in more corners of the insert body. For example, when the insert body has a polygonal plate shape, corners on the polygonal surfaces on the front and back sides are formed. Since the chip breaker can be formed in the portion, an economical and efficient cutting insert can be provided by effectively using one insert body.

  As described above, according to the present invention, chips can be surely curled and discharged in a desired direction even in copying turning and finishing turning of workpieces made of hardened steel, etc. It is possible to improve and control the discharge direction reliably, and it prevents high-precision and smooth operation by preventing a situation where chips are caught and damaged by the finished machining surface or chips are wound around the holder. It is possible to provide a cutting insert that can promote finishing and prevent breakage of the breaker wall surface and early wear and provide a long life.

  1 to 7 show a first embodiment of the present invention. In this embodiment, the insert body 1 is formed of a hard material such as cemented carbide and has a rhombic flat plate shape. One of the pair of rhombus surfaces is a rake face 2 and the other is the insert body 1. It is a seating surface 3 when being attached to a holder of an insert detachable cutting tool (not shown), and these rake face 2 and four side surfaces arranged around the seating face 3 are flank faces 4, and these flank face 4 and rake The intersecting ridge line with the surface 2 is a cutting edge 5. However, a chamfer 6 that intersects the rake face 2 and the flank 4 at an obtuse angle is formed along the cutting edge 5 with a constant width over the entire circumference of the rake face 2. In this chamfered portion 6, the intersection angle with the rake face 2 is made larger than the intersection angle with the flank face 4.

  Further, the intersecting ridge lines between the flank faces 4 adjacent to each other in the circumferential direction are convex curved surfaces that are in smooth contact with the flank faces 4, and in this embodiment, are convex cylindrical surfaces. In the four corners of the rake face 2 where the part and the rake face 2 intersect, the cutting edge 5 has a convex curve shape when viewed from the direction facing the rake face 2, and in the present embodiment, it has a convex arc shape. In addition, the chamfered portion 6 has a truncated cone shape in these corner portions. In the present embodiment, the apex angle of the corner portion C that forms an acute angle among the four corner portions is set to 80 °, and the flank 4 is formed in a direction perpendicular to the rake face 2, and the rake face 2 is further increased. From the center to the seating surface 3, a CNGA type cutting insert is formed in which a mounting hole 7 is formed through the insert body 1 in the thickness direction.

  Further, the pair of corner portions C that form the acute angle of the rake face 2 are formed by notching a portion including the corner portion C of the insert body 1, and a bottom face 8A parallel to the rake face 2 and the pair of corner parts C. A recess 8 having a wall surface 8B extending from the bottom surface 8A to the rake surface 2 perpendicular to the diagonal line L of the rake surface 2 connecting the corner portions C is formed. In this recess 8, a cutting edge tip 9 obtained by laminating a cemented carbide 9A and a cBN (cubic boron nitride) sintered body 9B in layers and integrally sintering the cBN sintered body 9B Are joined and fixed to the rake face 2 side by brazing or the like.

  Here, this cutting edge tip 9 is connected so as to be flush with the rake face 2 of the insert body 1, the flank 4, the chamfered portion 6, and the intersecting ridge line portion of the convex curved flank 4. Further, the thickness of the cBN sintered body 9B is the width from the rake face 2 to the intersecting ridge line between the chamfered portion 6 and the relief surface 4 (in the thickness direction of the chamfered portion 6). It is made larger than (width). Accordingly, in the vicinity of the corner portion C of the cutting edge 5, the cutting edge portion 5B extending in a straight line from the cutting edge portion 5A of the corner portion C having an arc shape smoothly contacts both ends of the cutting edge portion 5A. A portion up to a predetermined length is formed in this cBN sintered body 9B portion.

  Further, the chamfered portion 6 formed in the cBN sintered body 9B portion has a breaker bottom surface 10A facing the corner portion C and facing the rake face 2 side, and a breaker wall surface 10B rising with respect to the breaker bottom surface 10A. The chip breaker 10 is formed at the portion facing the corner portion C, and the breaker wall surface 10B is formed by the cutting edge portion 5A in the corner portion C in this embodiment. The shape is a convex curved surface that curves along the convex curve. Here, the chip breaker 10 is formed symmetrically on a plane extending in the thickness direction along the diagonal L, and in the present embodiment, the cutting edge 5A has an arc shape having a center on the diagonal L. On the other hand, the breaker wall surface 10B also has an arcuate shape in which the intersecting ridge line with the breaker bottom surface 10A of the portion facing the corner portion C is similarly centered on the diagonal L, and the radii thereof are also equal to each other.

  The breaker bottom surface 10 </ b> A is formed in a planar shape parallel to the rake surface 2 and the seating surface 3 with a certain distance from the intersecting ridge line between the chamfered portion 6 and the flank 4 to the rake surface 2 side. Accordingly, the width between the intersecting ridge line between the breaker bottom surface 10A and the chamfered portion 6 and the intersecting ridge line between the chamfered portion 6 and the flank 4 is also constant from the cutting edge portion 5A to the cutting edge portion 5B. Yes. On the other hand, in the breaker wall surface 10B, the portion located on the diagonal line L is designed to have the largest width from the breaker bottom surface 10A. However, even in this portion, it reaches the intersection ridgeline between the rake face 2 and the chamfered portion 6. The rake face 2 is formed at a distance from the rake face 2.

  Further, the breaker wall surface 10B faces the corner portion C, and both ends of the convex curved surface portion are in smooth contact with the convex curved surface when viewed from the direction facing the rake face 2, and the corner portion C has the top portion. It is formed so as to extend in a straight line approaching the intersecting ridge line side between the chamfered portion 6 and the breaker bottom surface 10A as it is separated from the diagonal line L at an angle larger than the angle (90 ° in the present embodiment). Therefore, the width of the breaker wall surface 10B and the width of the breaker bottom surface 10A gradually decrease from the position on the diagonal L along the cutting edge 5 toward the linear cutting edge 5B side, and the cBN sintered body In the 9B portion, the widths of the respective chip breakers 10 are defined so that the respective widths become 0, that is, the intersecting ridgelines of the chamfered portion 6 and the breaker bottom surface 10A and the breaker wall surface 10B intersect each other. Has been made.

  Furthermore, in the present embodiment, the breaker wall surface 10B has a vertical wall surface portion 11 perpendicular to the breaker bottom surface 10A on the breaker bottom surface 10A side, and is closer to the rake surface 2 side away from the breaker bottom surface 10A than the vertical wall surface portion 11. The portion is an inclined wall surface portion 12 that gradually retreats inside the corner portion C as it rises with respect to the breaker bottom surface 10A. Here, the width of the vertical wall surface portion 11 from the breaker bottom surface 10A is constant except for the end portion side of the chip breaker 10 where the width of the breaker wall surface 10B itself approaches 0, and in the portion on the diagonal L Is sufficiently smaller than the width of the inclined wall surface portion 12. Accordingly, the portion of the breaker wall surface 10B facing the corner portion C is formed in a convex cylindrical surface shape on the breaker bottom surface 10A side by the vertical wall surface portion 11, and the rake surface 2 side is formed in a convex cylindrical surface shape inclined by the inclined wall surface portion 12. Or it is set as the shape of a truncated cone, The inclination | tilt angle (theta) with respect to the vertical wall surface part 11 is 10 degrees in this embodiment.

  In the cutting insert configured as described above, first, the cutting edge 5 is formed in the cBN sintered body 9B portion of the cutting edge tip 9 around the corner portion C that forms an acute angle on the rake face 2 of the insert body 1. Even when turning the hardened steel or the like having a medium to high hardness using the cutting edge 5 around the corner portion C, it is possible to perform a reliable turning process without causing the cutting edge 5 to be damaged. it can. Moreover, since the chamfered portion 6 is formed on the cutting blade 5 including the corner portion C, the strength of the cutting blade 5 can be ensured more reliably.

  Further, a chip breaker 10 is formed in the chamfered portion 6 in the corner portion C, and a portion of the chip breaker 10 facing the corner portion C of the breaker wall surface 10B is formed by the cutting edge 5 in the corner portion C. Since the convex curved surface is curved along the convex curved cutting edge 5A, the distance between the cutting edge 5A and the breaker wall surface 10B is the cutting edge 5A of the corner C as shown in FIG. Can be prevented from changing significantly. Accordingly, when the workpiece is copied by using such a corner portion C, even if the cutting point on the cutting edge 5A of the corner portion C changes with the unevenness of the workpiece, the chips are separated by a predetermined distance. Can be made to collide with the wall surface 10B of the breaker, and this distance is too short to cause clogging of the chips. It is possible to prevent a situation such as hitting the processing surface and scratching it, and to promote smooth turning.

  In addition, the breaker wall surface 10B is a convex curved surface even if the cutting point in the cutting edge portion 5A is changed by this copying turning, so that the chip flow direction changes along the corner portion C. The chips that have collided with 10B are in sliding contact with the breaker wall surface 10B while being in surface contact with a certain amount of width around the generatrix along the generatrix of the cylindrical surface or the truncated cone surface formed by the convex curved surface. For this reason, sufficient resistance can be given to the chips that have collided with the breaker wall surface 10B, and the chips can be curled more reliably, and the discharge direction of the curled chips can be controlled in the direction along the generatrix. Therefore, smoother chip disposal can be achieved. In addition, since the breaker wall surface 10B is formed in a convex curved surface in this way, the breaker wall surface 10B can be brought close to the cutting edge portion 5A having a convex curve shape in the corner portion C. Even when thin chips are generated in turning or the like, it is possible to cause the chips to collide with the breaker wall surface 10B and curl before the chips are extended.

  Further, since the square portion is not formed on the breaker wall surface 10B, chipping occurs on such a portion intensively, so that the chip breaks or wear occurs at an early stage, and the breaker wall surface 10B is worn away. In combination with the fact that the strength of the cutting blade 5 is ensured as described above, a long-life cutting insert can be provided. In order to more reliably prevent the wear of the breaker wall surface 10B, the cBN firing of the breaker wall surface 10B, the entire chip breaker 10 including the breaker bottom surface 10A, or the cutting edge chip 9 including the chip breaker 10 is performed. It is desirable to coat the entire surface of the bonded body 9B or the entire surface of the insert body 1 including the rake face 2, the flank face 4, and the chamfered portion 6 with a hard film such as TiCN, TiAlN, TiN or the like. .

  In particular, in the cutting insert of the present embodiment, the curvature radius (radius) of the convex curve (convex arc) formed by the cutting edge portion 5A in the corner portion C of the cutting blade 5 and the curvature radius of the convex curved surface formed by the breaker wall surface 10B. (The radius of the convex arc formed by the intersecting ridge line with the breaker bottom surface 10A) is made equal to each other, so that the distance from the cutting edge 5A to the breaker wall surface 10B can be made even more uniform to further improve chip disposal. be able to. The radius of curvature of the breaker wall surface 10B may not exactly coincide with the radius of curvature of the cutting edge portion 5A, but is made equal within a range of ± 20% with respect to the curvature radius of the cutting edge portion 5A. It is desirable. In addition, the convex curve formed by these cutting edge portions 5A and the convex curve formed by the breaker wall surface 10B on the intersecting ridge line with the breaker bottom surface 10A may be an elliptical shape whose curvature radius changes.

  Further, in the present embodiment, the breaker wall surface 10B has a vertical wall surface portion 11 perpendicular to the breaker bottom surface 10A on the breaker bottom surface 10A side, while the rake face 2 side opposite to the breaker bottom surface 10A is relative to the breaker bottom surface 10A. The inclined wall surface portion 12 gradually recedes inside the corner portion C as it stands up. However, the breaker wall surface 10B may be the vertical wall surface portion 11 like the cutting insert described in Patent Document 3, for example. However, the inclined wall surface portion 12 is formed on the side away from the breaker bottom surface 10A. By forming it, it is possible to prevent resistance from acting too much on the chip, and for example, the chip can be quickly discharged to the rake face 2 side while being guided to the side away from the workpiece. It is possible to more reliably prevent a situation where the workpiece touches the processed surface.

  On the other hand, since the vertical wall surface portion 11 is formed on the breaker bottom surface 10A side of the breaker wall surface 10B, for example, as in Patent Document 1, the entire breaker wall surface is formed so as to rise from the bottom in a concave arc surface shape. Compared to the case where the entire breaker wall surface is inclined as in Patent Document 2, the contact area between the chips and the breaker wall surface 10B can be reduced to prevent an increase in resistance. In the case where the inclined wall surface portion 12 is formed as described above, if the inclination angle θ is excessively large, even if the chips collide with the breaker wall surface 10B, sufficient resistance is not given, or the chips are generated by the chip breaker 10. Therefore, the inclination angle θ is preferably set to a range of 60 ° or less at the position on the diagonal line L of the breaker wall surface 10B, and further set to a range of 45 ° or less. Is more desirable.

  Furthermore, in this embodiment, the breaker bottom surface 10A of the chip breaker 10 is formed in a plane parallel to the rake surface 2 and the seating surface 3 of the insert body 1, and the cutting insert is attached to the holder to turn the workpiece. When machining, the height of the breaker bottom surface 10A with respect to the rotation axis of the workpiece, that is, the core height position can be kept constant along the cutting edge 5 to hold the cutting insert. For this reason, for example, compared with the cutting insert etc. in which the breaker bottom face described in Patent Document 1 is inclined, the core of the breaker bottom face 10A facing the corner portion C, especially when the cutting point changes as in the above-mentioned profile turning. It is possible to prevent the high position from changing, and it is possible to perform more stable copying turning.

  In addition, since the breaker bottom surface 10A is parallel to the rake face 2 and the seating surface 3 of the insert body 1 in this way, in this embodiment, the insert thickness is the height from the seating surface 3 to the breaker bottom surface 10A. The height of the cutting blade 5 can be increased by the height from the breaker bottom surface 10A to the rake face 2, and thereby the angle of the cutting blade 5 with respect to the work material. Can be made more negative (negative). Therefore, by adopting such a configuration, it is possible to make the chips easily collide with the breaker wall surface 10B, and it is possible to further improve the chip disposal, and it is possible to reduce the cutting resistance. The effect that the cutting | disconnection of the blade 5 or the breaker wall surface 10B etc. can be prevented further reliably is also acquired.

  FIGS. 8 to 14 show a second embodiment of the present invention, and FIGS. 15 to 21 show a third embodiment of the present invention. Portions common to the forms are assigned the same reference numerals and description thereof is omitted. That is, in the first embodiment, the breaker wall surface 10B of the chip breaker 10 has a convex curved surface shape that curves along the convex curve formed by the cutting edge portion 5A in the corner portion C of the cutting edge 5. In these second and third embodiments, the breaker wall surface 10B has a multi-step surface shape of five or more stages that bends along the convex curve formed by the cutting edge part 5A in the corner part C of the cutting edge 5. This is a structural feature.

Here, in the second embodiment shown in FIGS. 8 to 12, the above configuration is applied to a CNGA type cutting insert in which the apex angle of the corner portion C forming an acute angle is 80 ° as in the first embodiment. The third embodiment shown in FIGS. 15 to 20 is a DNGA type cutting insert having an apex angle of 55 °. Moreover, the breaker wall face 10B, the portion facing to the corner portion C of the cutting edge 5A forms a convex curve, in the second embodiment is constituted by the step surface 10B ₁ ～10B ₉ of 9 stages, also the third embodiment of the In the embodiment, it is constituted by _seven step surfaces 10B _{1 to} 10B ₇ , and in the second and third embodiments, both are formed into an odd number of multi-step surfaces. In the second and third embodiments, the chip breaker 10 is formed symmetrically with respect to a plane extending in the thickness direction of the insert body 1 along the diagonal L, that is, a plane that bisects the corner portion C.

Further, the step surfaces 10B _{1 to} 10B ₉ and the step surfaces 10B _{1 to} 10B ₇ are all flat, but in a direction perpendicular to the breaker bottom surface 10A inside the corner portion C as it rises with respect to the breaker bottom surface 10A. On the other hand, similar to the inclined wall surface portion 12 of the first embodiment, the inclined plane is inclined so as to gradually recede at an equal inclination angle θ in the range of 60 ° or less. In the embodiment, both of the inclination angles θ are 20 °. In the breaker wall surface 10B in the second and third embodiments, the vertical wall surface portion 11 is not formed on the breaker bottom surface 10A side. Further, the crossing angles of the adjacent step surfaces 10B _{1 to} 10B ₉ and 10B _{1 to} 10B ₇ are equal to each other, and the obtuse angle is 173 ° in the second embodiment and 168 ° in the third embodiment.

Then, the multi-stage surface _10B 1 _{~10B 9,} stepped surface _10B 1 _{~10B 7} constituting the breaker wall face 10B facing the corner portion C is the curvature of the convex surface in contact with the convex bent portion intersecting the stage surface adjacent to each other The radius is made equal to the curvature radius of the convex curve formed by the cutting edge portion 5A in the corner portion C of the cutting edge 5. That is, in the second and third embodiments, the convex bent line formed by the portion of the breaker wall surface 10B facing the corner portion C intersecting the breaker bottom surface 10A is the convex curve (second curve) formed by the cutting blade portion 5A. In the third embodiment, it is formed so as to be inscribed in a convex curve having a radius of curvature equal to that of the arc). In addition, the curvature radius of the convex curve inscribed by the broken line may be within a range of ± 20% of the curvature radius of the convex curve formed by the cutting edge portion 5A.

Furthermore, as described above, the portion of the breaker wall surface 10B facing the corner portion C has an odd-numbered multi-stage shape, and is symmetrical to a plane extending in the thickness direction along the diagonal line L. In the second embodiment, the fifth step surface 10B ₅ is arranged, and in the third embodiment, the fourth step surface 10B ₄ is arranged so as to be orthogonal to the plane. Further, stepped surface _10B 1 of the 1,9-stage of the second embodiment is located at both ends of the portion facing to the corner portion C, 10B ₉ a third embodiment 1,7 step surface of the stepped surface 10B of the _first , 10B ₇ is connected to the inclined flat surface portions at both ends of the breaker wall surface 10B facing the linear cutting edge portion 5B of the cutting blade 5 so as to bend and bend at an obtuse angle. As in the first embodiment, the chamfered portion 6 and the chamfered portion 6 form an angle larger than the apex angle of the corner portion C (90 ° in the second embodiment, 84 ° in the third embodiment) and away from the diagonal L. It is formed to extend in a straight line approaching the crossing ridge line side with the breaker bottom surface 10A.

  In the second and third embodiments configured as described above, the chip breaker wall surface 10B of the chip breaker 10 is multi-stage, but the number of stages is as large as five or more and is approximately the same as in the first embodiment. Therefore, the distance between the cutting edge part 5A and the breaker wall surface 10B at the corner part C of the cutting edge 5 can be made substantially constant, and clogging and elongation of chips can be achieved. It is possible to prevent wrapping around the holder due to slight chips, and it is possible to bring the breaker wall surface 10B closer to the cutting edge portion 5A. In addition, although an intersecting ridge line is formed between adjacent step surfaces, since it is a multi-step surface, the intersecting angle between the step surfaces in this intersecting ridge line can be made a larger obtuse angle, and chips along this intersecting ridge line While slidable contact can reduce chipping and wear, chips can be brought into surface contact with a certain width rather than line contact to provide sufficient resistance, and the cross ridge lines can be reliably guided in the extending direction. It becomes possible to do.

  Further, as in the second and third embodiments, it is the first embodiment that the breaker wall surface 10B is formed into a multi-step surface curved along a convex curve formed by the corner portion C by a flat step surface. Compared with the case where the convex curved surface breaker wall 10B is curved accurately along the convex curved surface, it is easy because only the grindstone that forms the stepped surface and the terminals of the electric discharge machine need only be moved linearly. There is also an advantage that a desired accuracy can be easily obtained. However, this advantage is lost if the number of steps of the multi-step surface is too large, and conversely, if the number of steps is small, the crossing angle between adjacent step surfaces becomes small, and the above effect may not be sufficiently achieved. Therefore, depending on the size of the insert body 1 and the apex angle of the corner portion C, when the portion facing the corner portion C of the breaker wall surface 10B is formed in a multi-step shape in this way, both end portions of the breaker wall surface 10B are formed. Except for this, the number of stages is preferably about 5 to 15.

On the other hand, in the second and third embodiments, the multistage surface of the breaker wall surface 10B facing the corner portion C is an odd-numbered step, and the chip breaker 10 has the thickness along the bisector L. Since it is symmetric with respect to the plane extending in the vertical direction, the central step surfaces 10B ₅ and 10B ₄ are located on the bisector L perpendicular to the plane. For this reason, when the cutting edge 5 of the part on the bisector L is used in the corner portion C in normal finish turning or the like, and the chips flow out along the bisector L. , even chips to be stretched slightly by for a small thickness, while curling by providing a resistance to ensure surface contact with the stepped surface _10B 5, 10B ₄ of the central, along the stepped surface _10B 5, 10B ₄ It is possible to control the discharge direction with certainty.

  In the second and third embodiments, the breaker wall surface 10B is gradually moved away from the breaker bottom surface 10A toward the rake face 2 side gradually at an inclination angle θ with respect to the direction perpendicular to the breaker bottom surface 10A. Since it is set as the inclined surface which recedes, and the vertical wall surface part 11 like 1st Embodiment is not formed, formation of the said breaker wall surface 10B is still easier, but it is the same vertical as 1st Embodiment. The wall surface portion 11 may be formed on the breaker bottom surface 10A side, and conversely, the breaker wall surface 10B may be formed entirely by the inclined wall surface portion 12 without forming the vertical wall surface portion 11 in the first embodiment. Furthermore, as described above, in the first to third embodiments, the entire breaker wall surface 10B may be formed perpendicular to the breaker bottom surface 10A. However, when the breaker wall surface 10B is partially inclined, the inclination angle θ is preferably 60 ° or less, more preferably 45 ° or less, and preferably smaller than the inclination angle of the chamfered portion 6. .

  By the way, in each of these first to third embodiments, only one rhombus surface of the rhombic flat plate-like insert body is the rake face 2, and the other rhombus face is the seating face 3. The above-mentioned chip breaker 10 is formed by disposing a cutting edge chip 9 in a corner portion C forming a pair of acute angles. In particular, the breaker wall surface 10B of this chip breaker 10 is as in the second and third embodiments. Since it is easy to form as described above when it is a multi-stage surface, the time, labor, and cost for forming the chip breaker 10 in one corner portion C can be reduced, and conversely, the same time, labor, and cost are spent. Then, since the chip breaker 10 can be formed in more corner parts C, for example, as in the fourth embodiment shown in FIGS. 22 to 25, a total of four corner parts C of both rhombus faces. It is possible to form a chip breaker 10 is disposed cutting edge tip 9. In this case, one of the pair of rhombus surfaces is selectively a rake surface 2 and the other is a seating surface 3, and the insert body 1 is turned upside down so that the cutting edges 5 around the four corner portions C of both rhombus surfaces. Are provided for sequential use.

  Therefore, in the cutting insert according to the fourth embodiment, the number of corner portions C that can be used in one insert body 1 is doubled. Therefore, the insert body 1 can be used effectively to provide an economical cutting insert. In addition, since the number of inserts required for a predetermined cutting process is halved, the management becomes easy and an efficient operation can be performed. In the cutting insert of the fourth embodiment, the pair of rhombus surfaces are symmetrical with each other so that the plan view shown in FIG. 23 is also a bottom view. In the fourth embodiment, the chip breaker 10 having the multi-stage surface breaker wall surface 10B of the second embodiment is applied. However, the chip breaker 10 has the convex curved surface wall surface 10B of the first embodiment. The chip breaker 10 may be used. Furthermore, the present invention is naturally applicable to cutting inserts having various shapes such as a TNGA type cutting insert having a regular triangular flat plate shape other than the rhombus flat plate cutting insert as in the above-described embodiment.

1 is a perspective view showing a first embodiment of the present invention. It is the top view which looked at the embodiment shown in FIG. 1 from the direction facing the rake face 2. It is the side view which looked at the embodiment shown in FIG. 1 from the corner part C side which makes the acute angle of the rake face 2. FIG. It is the side view which looked at the embodiment shown in FIG. 1 from the corner part side which makes the obtuse angle of the rake face 2. It is the bottom view which looked at the embodiment shown in Drawing 1 from the seating surface 3 side. FIG. 3 is an enlarged plan view around a corner portion C in FIG. 2. FIG. 5 is an enlarged side view around a corner portion C in FIG. 4. It is a perspective view which shows the 2nd Embodiment of this invention. It is the top view which looked at the embodiment shown in FIG. 8 from the direction facing the rake face 2. It is the side view which looked at the embodiment shown in FIG. 8 from the corner part C side which makes the acute angle of the rake face 2. It is the side view which looked at the embodiment shown in FIG. 8 from the corner part side which makes the obtuse angle of the rake face 2. It is the bottom view which looked at embodiment shown in FIG. 8 from the seating surface 3 side. FIG. 10 is an enlarged plan view around a corner portion C in FIG. 9. FIG. 12 is an enlarged side view around a corner portion C in FIG. 11. It is a perspective view which shows the 3rd Embodiment of this invention. It is the top view which looked at embodiment shown in FIG. 15 from the direction which opposes the rake face 2. FIG. It is the side view which looked at the embodiment shown in FIG. 15 from the corner part C side which makes the acute angle of the rake face 2. FIG. It is the side view which looked at embodiment shown in FIG. 15 from the corner part side which makes the obtuse angle of the rake face 2. FIG. It is the bottom view which looked at embodiment shown in FIG. 15 from the seating surface 3 side. FIG. 17 is an enlarged plan view around a corner portion C in FIG. 16. FIG. 19 is an enlarged side view around a corner portion C in FIG. 18. It is a perspective view which shows the 4th Embodiment of this invention. FIG. 23 is a plan view of the embodiment shown in FIG. 22 viewed from the direction facing the rake face 2 or a bottom view viewed from the direction facing the seating surface 3. It is the side view which looked at the embodiment shown in FIG. 22 from the corner part C side which makes the acute angle of the rake face 2. FIG. It is the side view which looked at the embodiment shown in FIG. 22 from the corner part side which makes the obtuse angle of the rake face 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insert body 2 Rake face 4 Flank 5 Cutting edge 5A Arc-shaped cutting edge part 5B in the corner part C of the cutting edge 5 Straight cutting edge part 5 of the cutting edge 5 connected to the cutting edge part 5A 6 Chamfering part 9 Cutting edge Chip 9B cBN sintered body 10 Chip breaker 10A Breaker bottom surface 10B Breaker wall surface 10B _{1 to} 10B Multi-stage surface forming a portion facing the corner portion C of ₉ breaker wall surface 10B 11 Vertical wall surface portion 12 Inclined wall surface portion L Rhombus formed by rake face 2 Diagonal line connecting the corner C of the angle θ The inclination angle of the inclined wall portion 12

Claims (5)

  The periphery of the corner portion of the cutting edge formed in the insert body is formed of a cBN sintered body, and a chamfered portion is formed along the cutting edge in the corner portion, and the chamfered portion faces the corner portion. A cutting insert in which a chip breaker having a breaker bottom surface facing the rake face side of the cutting blade and a breaker wall surface rising with respect to the breaker bottom surface is formed, and the chip breaker is a portion facing the corner portion Wherein the breaker wall surface has a convex curved surface shape that curves along a convex curve formed by the corner portion, or a multistage surface shape that has five or more steps that curves convexly along the convex curve. insert.   The curvature radius of the convex curved surface formed by the breaker wall surface or the curvature radius of the convex curved surface in contact with the multi-step convex curved portion formed by the breaker wall surface is within a range of ± 20% of the curvature radius of the convex curve formed by the corner portion. The cutting insert according to claim 1, wherein the cutting insert is provided.   The breaker wall surface is inclined so as to gradually recede within a range of 60 ° or less with respect to a direction perpendicular to the breaker bottom surface inside the corner portion as it rises perpendicular to the breaker bottom surface or rises with respect to the breaker bottom surface. The cutting insert according to claim 1, wherein the cutting insert is provided.   The breaker wall surface includes a vertical wall surface portion perpendicular to the breaker bottom surface on the breaker bottom surface side, and gradually recedes to the inside of the corner portion as it rises with respect to the breaker bottom surface on the side away from the breaker bottom surface. The cutting insert according to claim 1, further comprising an inclined wall surface portion.   The cutting body according to any one of claims 1 to 4, wherein the insert body has a polygonal flat plate shape, and the chip breaker is formed at a corner portion of a polygonal surface on the front and back sides thereof. insert.

Images