JP2011115896A - Cutting insert - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting insert capable of providing high finishing surface accuracy, while lengthening the tool service life by restraining generation of a burr, in machining work of a difficult-to-cut material such as stainless steel. <P>SOLUTION: A corner blade 7 forming a projecting circular arc shape in a plan view opposed to a rake surface 2, is formed in a corner part C of the rake surface 2 of an insert body 1. This corner blade 7 is formed as an inclined cutting edge 8 inclined so as to gradually retreat in the opposed direction to the rake surface 2 toward both end part S sides from a projecting end part R of a projecting circular arc formed by the coiner blade 7 in a plan view. Both end parts S of this corner blade 7 are formed with an inversely inclined cutting edge 9 extending in the tangent direction of the projecting circular arc in both end parts S in the plan view and inclined so as to gradually protrude in the opposed direction to the rake surface 2 toward the separating direction to the corner blade 7 from an end part of the inclined cutting edge 8. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention particularly relates to a cutting insert used for turning difficult-to-cut materials such as stainless steel.

  For example, in Patent Document 1, burrs are likely to occur when such a difficult-to-cut material such as stainless steel is cut, and this burrs cause work hardening and are extremely poor in machinability. It is described that the chipping at the cutting boundary that meets this burr has large chipping, and there is a problem that the cutting edge is lost or the tool life is extremely shortened due to so-called abnormal wear.

  Therefore, this Patent Document 1 discloses that the cutting edge is larger than 0 ° and larger than 20 ° so that the distance of the cutting edge from the bottom surface of the flat insert body is small at the corner and increases toward the center of the cutting edge. It is formed in a substantially straight line with a small inclination angle, and the angle of the chip breaker rake face of the upper chip breaker is set to 20 ° to 30 °, and the inner part of this chip breaker rake face extends from the bottom part of the chip breaker to the inner part. A cutting insert has been proposed in which a breaker wall that rises in a direction in which the height from the bottom surface gradually increases is formed, and an inner upper surface portion of the chip breaker is lower than a peripheral cutting edge portion.

  According to such a cutting insert, even when difficult-to-cut materials such as stainless steel are cut by increasing the angle of inclination of the cutting edge, it is possible to reduce the occurrence of burrs, and to prevent abnormal wear as much as possible to reduce tool life. The so-called sticky chips of difficult-to-cut materials can be reliably divided by the above-mentioned chip breaker breaker wall, and even when the chips move along the breaker wall, the resistance to movement Can be reduced to prevent heat generation. Therefore, a cutting insert having a stable tool life can be obtained.

Japanese Utility Model Publication No. 63-42965

  However, in such a cutting insert formed so that the cutting edge is inclined in a substantially straight line so that the distance of the cutting edge from the bottom surface of the insert main body is small at the corner and increases as it goes to the central part of the cutting edge, Since the rake angle in the radial direction is remarkably reduced, the cutting resistance may increase at the feed boundary and the finished surface may be deteriorated. On the other hand, if the inclination of the cutting edge is reversed so that the distance of the cutting edge from the bottom surface is large at the corner and becomes small as it goes to the center of the cutting edge, especially in turning of stainless steel, etc. Chips that flow out toward the rear side are curled sideways and discharged so as to extend in the feed direction, so that distortion at the incision boundary increases and burrs due to deformation of the work material are likely to occur.

  The present invention has been made under such a background, and in turning difficult-to-cut materials such as stainless steel, it is possible to suppress the generation of burrs and extend the tool life, and to obtain high finished surface accuracy. The aim is to provide a possible cutting insert.

  In order to solve the above problems and achieve such an object, according to the present invention, a corner blade having a convex arc shape in a plan view facing the rake face is formed at a corner portion of the rake face of the insert body. The corner blade is an inclined cutting blade that is inclined so as to gradually recede in a direction facing the rake face as it goes from the protruding end portion of the convex arc formed by the corner blade in the plan view toward both ends. In addition, the corner blades extend in the direction tangential to the convex arc at the both ends in the plan view, and extend from the end of the inclined cutting blade toward the corner blade in a direction away from the corner blade. A reverse inclined cutting edge is formed so as to be gradually raised with respect to the direction facing the rake face.

  In such a cutting insert, the corner blades are inclined cutting edges that gradually recede toward the both ends from the projecting end portions, and the corner blades in the radial direction of the corner blades that are located at the feed boundary portions are formed. The rake angle can be increased to ensure sharpness, cutting resistance can be reduced, and finished surface accuracy can be improved. On the other hand, opposite corners of the corner blade are formed with oppositely inclined cutting edges that are inclined so as to gradually rise in the direction away from the corner blade, contrary to the inclined cutting edge. The inclined cutting edge prevents the chips that flow out to the rear side in the feed direction from curling sideways and can be discharged to the rear side in the feed direction as it is, reducing the strain at the cutting boundary of the work material, It is possible to suppress the generation of burrs due to deformation of the work material.

  However, if the inclination of the inclined cutting edge and the reverse inclined cutting edge is both gentle, the cutting edge continues from the tip end portion of the corner blade so as to extend along a single plane. There is a risk that it will not be possible. On the other hand, if the inclination of the inclined cutting edge becomes too large, the edge strength at the corner blade cannot be secured, and there is a risk of causing chipping or chipping, and when the inclination of the reverse inclined cutting edge is too large. Chips are generated in a shape that is greatly bent into a V-shaped cross section, and on the contrary, distortion at the incision boundary increases.

  For this reason, with respect to these inclination angles, when a flat seating surface is formed on the opposite side of the rake face of the insert body, a plane parallel to the seating surface on the basis of the plane parallel to the seating surface. It is desirable that the inclination angle of the inclined cutting edge is in the range of 0 ° to 10 °, and the inclination angle of the reverse inclination cutting edge is in the range of 0 ° to 10 °. Of course, both the inclination angle of the inclined cutting edge and the inclination angle of the reverse inclination cutting edge are not 0 °.

  Further, by providing the rake face in the corner part with a positive rake face part gradually retreating from the periphery of the rake face toward the inside, and a bottom face part connected to the positive rake face part, the shear angle and Since the cutting ratio increases and thin chips are generated, the generation of burrs due to the deformation of the material can be more reliably suppressed. Furthermore, by forming a projecting breaker on the bottom surface, it is possible to curl and process the generated chips. However, if the height of the breaker is too high, chips are formed particularly in stainless steel. Since it curls sideways, this breaker is formed to have a height that does not exceed the inclined cutting edge and the reverse inclined cutting edge when viewed from a direction perpendicular to the plane that bisects the corner portion. Is desirable.

  In addition, when this breaker is formed so as to form a ridge extending along a plane that bisects the corner portion, the height of the breaker is set to a plane that bisects the corner portion as described above. To make the height not to exceed the above-mentioned inclined cutting edge and the reverse inclined cutting edge when viewed from the orthogonal direction, for example, the top of the breaker that forms this ridge shape is inclined at a constant height and the inclined cutting edge. The height may not exceed the cutting edge, but in this case, both ends of the breaker may be too low with respect to the inclined cutting edge and the reverse inclined cutting edge, and the chip may not be curled sufficiently. .

  Therefore, when the breaker is formed in a ridge shape extending along a plane that bisects the corner portion in this way, the corner blade side when viewed from the direction orthogonal to the plane It is desirable that it is formed so as to incline so as to gradually recede in accordance with the inclined cutting edge toward the inside of the rake face, and then incline so as to gradually rise in accordance with the reverse inclined cutting edge. Over the entire length of the cutting edge from the inclined cutting edge to the reverse inclination cutting edge, it is possible to promote stable chip curl with the height of the breaker relative to the cutting edge being substantially constant.

  As described above, according to the present invention, as the inclined cutting edge that inclines so that the corner blade positioned at the feed boundary portion gradually recedes, the cutting is performed by increasing the rake angle in the radial direction and ensuring sharpness. While it is possible to reduce resistance and improve the accuracy of the finished surface, by forming reverse inclined cutting edges that incline so as to be gradually raised opposite to the inclined cutting edges at both ends of the corner blades, Therefore, it is possible to reduce the distortion at the boundary of the cut and to prevent the occurrence of burrs due to the large deformation of the work material. Therefore, even when turning difficult-to-cut materials such as stainless steel, tool life can be prolonged by preventing chipping, abnormal wear, and chipping of the cutting edge, and high-precision and high-quality machining surfaces can be obtained. Can do.

It is a perspective view which shows one Embodiment of this invention. It is the top view which looked at the embodiment shown in Drawing 1 from the direction which counters a rake face. It is a side view of the arrow A direction view in FIG. It is a side view of the arrow B direction view in FIG. It is a side view of the arrow C direction view in FIG. It is an expansion perspective view of the corner part of embodiment shown in FIG. FIG. 3 is a partially enlarged side view when viewed in the direction of arrow A in FIG. 2. It is a partially expanded side view of the arrow C direction view in FIG. It is UU sectional drawing in FIG. It is VV sectional drawing in FIG. It is WW sectional drawing in FIG. It is XX sectional drawing in FIG. It is YY sectional drawing in FIG. FIG. 3 is a partially enlarged view of a UU cross section in FIG. 2. FIG. 3 is a partially enlarged view of a ZZ cross section in FIG. 2.

  1 to 15 show an embodiment of the present invention. In the present 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 selectively a rake face 2 and the other is illustrated. It is set as the seating surface 3 to the insert mounting seat of the blade-tip-exchange-type tool which is not performed. However, in FIGS. 1 to 15, the upper rhombus surface is the rake face 2 and the lower rhombus surface is the seating surface 3. However, in the cutting insert of the present embodiment, the insert body 1 is front and back with respect to the pair of rhombus surfaces. By reversing the front and back of the insert body 1 in this way, the lower rhombus surface is the rake face 2 and the upper rhombus face is the seating surface 3.

  Further, the insert body 1 is formed with an attachment hole 4 which opens in the center of the rhombus surfaces on the front and back sides and penetrates the insert body 1, and the attachment pin of the above-mentioned blade edge replaceable tool is engaged with this attachment hole 4. For example, the cutting insert is detachably attached to the insert mounting seat. Here, the cutting insert of the present embodiment has a plane P in which the insert body 1 includes the center line of the mounting hole 4 and bisects the acute corner portion C of the rhomboid surface, and an obtuse corner of the rhomboid surface. The plane Q that bisects the portion D is also symmetrical, and is perpendicular to the center line in the thickness direction of the insert body 1 (up and down in FIGS. 3 to 5 and FIGS. 7 to 15). In the direction) with respect to a plane located at the center of the insert body 1.

  On the other hand, the four peripheral surfaces arranged around the front and back rhombus surfaces are formed so as to extend in parallel to the center line to be flank surfaces 5. A cutting edge 6 is formed in the part. Accordingly, the cutting insert of the present embodiment is a negative insert in which the clearance angle is not given to the cutting edge 6 in advance. Further, the acute corner portion C and the obtuse corner portion D of the rhombus surface are formed so as to form a convex arc shape in a plan view facing the rake face 2 along the center line. The cutting edge 6 in D is a corner edge 7, and therefore the flank 5 connected to the corner edge 7 has a cylindrical surface extending parallel to the center line.

  Then, the corner blade 7 is formed on the opposite ends S of the corner blade 7 from the protrusion R of the convex arc formed by the corner blade 7 in the plan view, that is, from the intersection of the corner blade 7 and the planes P and Q. As it goes, it gradually recedes in the direction facing the rake face 2 toward the seating face 3 opposite to the rake face 2 on which the corner blade 7 is formed, that is, gradually recedes in the thickness direction. It is set as the inclined cutting edge 8 inclined so that it might do.

  On the other hand, from the both ends S of this corner blade 7, it extends linearly in the tangential direction of the convex arc formed by the corner blade 7 at the both ends S in the above-mentioned plan view, and the adjacent acute angle corner portion C and obtuse angle corner portion. Contrary to the corner blade 7 that is the inclined cutting edge 8 as described above, the cutting edge 6 linking D is separated from the corner blade 7 (as it is separated from the protrusion R of the corner blade 7). The ridge is separated from the seating surface 3 opposite to the rake face 2 on which the cutting edge 6 is formed and gradually retreats in the direction facing the rake face 2, that is, gradually rises in the thickness direction. The reverse inclined cutting edge 9 inclined so as to be formed is formed.

  Here, in the present embodiment, the entire corner blade 7 having a convex arc shape in the plan view is the inclined cutting edge 8, and further extends beyond both end portions S of the corner blade 7 to be linear in the plan view. A part of the extending cutting edge 6 that is very short on the corner blade 7 side is an inclined cutting edge 8. The inclined cutting edge 8 is formed so as to extend along the inclined planes orthogonal to the planes P and Q of the corner portions C and D, respectively, with the protrusion R of the corner blade 7 as the apex. When viewed from the direction orthogonal to each of the planes P and Q, the inclined cutting edge 8 retreats in the thickness direction at a constant inclination angle as it is separated from the protrusion R as shown in FIGS. An inclined straight line will be exhibited.

  On the other hand, the reverse inclined cutting edge 9 is also formed so as to extend along the reverse inclined plane inclined in the direction opposite to the inclined plane on which the inclined cutting edge 8 is formed. When viewed from the direction orthogonal to Q, the reversely inclined cutting edge 9 exhibits a linear shape that is inclined so as to rise in the thickness direction at a constant inclination angle as shown in FIGS. 3 and 4. It is formed so as to be bent in a “<” shape together with the inclined cutting edge 8.

  Further, the reverse inclined cutting edge 9 inclined so as to rise linearly as it is separated from the corner blade 7 is as shown in FIG. 5 in a side view facing the flank 5 on the side away from the corner blade 7. In this way, it reaches the most prominent apex T in the form of a convex curve such as a convex arc that smoothly touches the straight line, and the apex T is located at a position that protrudes beyond the protruding end R of the corner blade 7 in the thickness direction. Furthermore, the cutting edge 6 on the side farther from the corner blade 7 than the top portion T forms a concave curve that smoothly touches the convex curve and recedes in the thickness direction, and then a straight line perpendicular to the thickness direction. It extends so as to form a shape and connects adjacent corner portions C and D.

  Further, the rake face 2 has the thickness as the outer peripheral edge side where the cutting edge 6 including the corner blade 7 is formed is directed from the peripheral edge to the inner side of the rake face 2 perpendicularly to the cutting edge 6 in the plan view. The positive rake face portion 2A is inclined so as to gradually recede in the direction, and the further inside of the positive rake face portion 2A is at least a gentler slope than the positive rake face portion 2A and gradually recedes toward the inside of the rake face 2. Alternatively, the bottom surface 2B extends perpendicularly to the thickness direction and intersects the positive rake surface 2A at an obtuse angle. However, the cutting edge 6 is provided with the inclined cutting edge 8 and the reverse inclined cutting edge 9 as described above and is uneven in the thickness direction, and accordingly, the positive rake face portion 2A and the bottom face portion 2B of the rake face 2 are provided. Similarly, it is formed so as to be uneven in the direction along the cutting edge 6.

  Further, the sharp corner portion C of the corner portions C and D is formed with a projecting breaker 10 protruding from the bottom surface portion 2B of the rake face 2. In this embodiment, the breaker 10 protrudes from the boundary portion between the positive rake face portion 2A and the bottom face portion 2B connected to the corner blade 7 of the acute corner portion C, and extends along the plane P of the acute corner portion C. It is formed in a strip shape, and in the above-described plan view, the corner blade 7 is formed to have a narrow and substantially constant width, while on the inner side of the rake face 2 away from the corner blade 7, the corner blade 7 It is formed so as to gradually become wider as it is separated from the edge, and is formed so as to have a substantially maximum width at a position from the top T of the reverse inclined cutting edge 9 to the inside of the rake face 2 perpendicular to the cutting edge 6. Yes.

  Further, the breaker 10 protrudes in a substantially isosceles trapezoidal shape as shown in FIG. 12 in a cross section taken along a plane perpendicular to the plane P and along the thickness direction, provided that the protrusion 10A Has a concave V-shaped cross section that is inclined so as to slightly recede in the thickness direction toward the center in the width direction located on the plane P.

  Further, the protrusion 10A of the breaker 10 is formed so as not to cross the inclined cutting edge 8 and the reverse inclined cutting edge 9 of the cutting edge 6 in the thickness direction when viewed from the direction orthogonal to the plane P. In particular, in this embodiment, as shown in FIG. 14, in a cross section along the plane P, the boundary portion between the positive rake face portion 2A and the bottom face portion 2B is gradually inclined toward the inside of the rake face 2 at a constant inclination angle. After the bulging, it is gradually retreated linearly at a constant inclination angle in accordance with the inclined cutting edge 8, and then is gradually raised again linearly at a constant inclination angle in accordance with the reverse inclined cutting edge 9. The protrusion 10 </ b> A is bent in a letter shape so that it does not exceed the inclined cutting edge 8 and the reverse inclined cutting edge 9 when viewed from the direction perpendicular to the plane P.

  The boss portion 11 further protrudes further in the thickness direction than the breaker 10 on the inner side of the rake face 2 than the breaker 10 of the acute corner portion C and on the inner side of the rake face 2 of the obtuse corner portion D. Are formed respectively. In the present embodiment, these boss portions 11 have a body portion 11A extending along the planes P and Q in the above-described plan view, and blades are continuously spread on both sides of the body portion 11A via constrictions. The boss portion 11 on the acute corner portion C side has a blade portion 11B that is longer than the body portion 11A and has a corner portion. While the boss 11 of the obtuse corner portion D is formed so as to expand in a V shape from the C side, the blade portion 11B is slightly shorter than the body portion 11A and the rake surface 2 is substantially parallel to the body portion 11A. It is formed to extend inward.

  Furthermore, the projecting top surfaces (boss surfaces) 11C of the boss portions 11 formed on the front and back rhombus surfaces of the insert body 1 are located on one plane perpendicular to the thickness direction in each rhombus surface. In addition, it is arranged at a position that protrudes most beyond the cutting edge 6 in the thickness direction. Therefore, when this rhombus surface is used as the seating surface 3, the projecting top surface 11C is in close contact with the flat bottom surface of the insert mounting seat, and the insert body 1 is seated. The boss portion 11 of the acute corner portion C extends so that the protruding end of the body portion 11A on the corner blade 7 side overlaps the protruding top surface 10A of the breaker 10 as shown in FIG.

  The cutting insert configured as described above is used for turning difficult-to-cut materials such as stainless steel by using the cutting edge 6 including the corner blade 7 formed in the acute corner portion C. Here, in such turning, the corner blade 7 is cut in the radial direction from the outer peripheral surface of the work material with a predetermined cut amount, and the insert body 1 is sent out in the rotation axis direction of the work material. As a result, a concave surface obtained by transferring the convex arc formed by the corner blade 7 forms a finished surface having a continuous cross section on the work material at a pitch corresponding to the feed of each work material. It is located at the feed boundary that is the boundary between the concave arc formed by the cross section of the finished surface formed previously and the concave arc formed by the cross section of the finished surface that is actually cut by feed.

  Thus, in the cutting insert having the above-described configuration, the corner blade 7 that forms the finished surface located at the feed boundary in this way gradually recedes in the thickness direction of the insert body 1 from the projecting end R toward both ends S. In this way, the cutting edge 8 is inclined so that the rake angle in the radial direction of the corner blade 7 can be increased. Accuracy can be improved and cutting resistance can be reduced. In particular, in the present embodiment, the positive rake in which the peripheral side of the rake face 2 connected to the cutting edge 6 includes the portion connected to the corner edge 7 and gradually recedes in the thickness direction as it goes to the inner side of the rake face 2. Therefore, the substantial rake angle in the cross section perpendicular to the corner blade 7 is increased to the positive angle side, and a sharper sharpness can be secured.

  On the other hand, the cutting edge 6 extending from both end portions S of the corner blade 7 is the outer periphery in which the cutting edge 6 extending from the end portion S on the feed direction side of the insert body 1 is a boundary portion for cutting into the work material. The chip 6 is generated by scraping the work material between the outer peripheral surface and the finished surface located on the surface, and the cutting edge 6 extending to both ends S side of the corner blade 7 is formed from the corner blade 7 side. In contrast to the inclined cutting edge 8, the reverse inclined cutting edge 9 is inclined so as to gradually rise in the thickness direction of the insert body 1 as it is separated.

  For this reason, the chips generated by the reverse inclined cutting edge 9 are directed toward the direction toward the inner peripheral side of the work material, and the chips flowing out to the rear side in the feed direction are left as they are. When the chips once flown out to the rear side in the feed direction curl sideways and return to the feed direction side, the deformation increases and the strain at the cutting boundary of the work material also increases. It is possible to prevent burrs from being easily generated at the cut boundary due to such strain.

  Therefore, according to the cutting insert having the above-described configuration, even in turning of difficult-to-cut materials such as stainless steel as described above, a cutting surface is suppressed at the feed boundary portion to form a high-quality and high finished surface precision processing surface. In addition, it is possible to suppress the generation of burrs at the incision boundary, and it is possible to extend the tool life by preventing chipping, abnormal wear and chipping of the cutting insert due to such burrs. . Further, particularly in the present embodiment, the reverse inclined cutting edge 9 extending from both end portions S of the corner blade 7 is also sharp because the peripheral side of the rake face 2 connected to the cutting edge 6 is the positive rake face portion 2A as described above. Since the sharpness can be ensured, the generation of burrs can be more reliably suppressed.

  In this way, even if the corner blade 7 is the inclined cutting edge 8 and the cutting edge 6 connected to both ends S thereof is the reverse inclined cutting edge 9, the inclined cutting edge 8 and the reverse inclined cutting edge 9 are inclined. If both are gentle, the cutting edge 6 is formed so as to continuously extend from the corner edge 7 along a single plane, and thus it may be difficult to reliably achieve the above-described effects. . On the other hand, if the inclination of the inclined cutting edge 8 of the corner blade 7 is too large, the cutting edge angle of the corner blade 7 may be reduced, and the strength of the cutting edge may not be ensured. If the inclination is too large, the chips generated by the corner blade 7 which is the inclined cutting edge 8 are generated in a state of being greatly bent into a V-shaped cross section. On the contrary, the distortion becomes large and may cause burrs.

  For this reason, when the insert body 1 has a flat plate shape as in the present embodiment, the inclination angle of the inclined cutting edge 8 is based on a plane perpendicular to the thickness direction, that is, for example, perpendicular to the thickness direction. It is desirable that the inclination angle α with respect to the plane parallel to the top surface 11C of the boss 11 on the seating surface 3 side located on one plane is in the range of 0 ° to 10 ° of 10 ° or less, and vice versa. It is desirable that the inclination angle β of the inclined cutting edge 9 with respect to the top surface is also in the range of 0 ° to 10 °, which is 10 ° or less. Of course, when the inclination angles α and β are both 0 °, the inclined cutting edge 8 and the reverse inclined cutting edge 9 are both located on a plane parallel to the top surface 11C. Both β are not 0 °. Of these, the inclination angle α of the inclined cutting edge 8 is preferably made smaller than the inclination angle with respect to the plane perpendicular to the thickness direction of the positive rake face portion 2A connected to the corner edge 7 in particular.

  On the other hand, in the present embodiment, the positive rake face portion 2A that gradually recedes from the peripheral edge where the cutting edge 6 is formed toward the inside of the rake face 2 is formed on the peripheral edge portion of the rake face 2 in this way. As described above, the sharpness of the cutting edge 6 can be maintained sharply even with the reverse inclined cutting edge 9 to increase the shear angle and the cutting ratio, and the chip can be made thinner to further reduce the cutting resistance and suppress the burr. Can be planned.

  Further, a bottom surface portion 2B having a gentler slope than that of the positive rake surface portion 2A or perpendicular to the thickness direction is formed so as to be continuous with the positive rake surface portion 2A. By bringing the chips flowing along the surface portion 2A into sliding contact with the bottom surface portion 2B, a certain amount of resistance can be given to the chips even if they are not curled sideways as described above. Therefore, the chips can be curled while being discharged to the rear side in the feed direction, and smooth processing thereof can be achieved.

  Further, in the present embodiment, in the acute corner portion C used exclusively for turning, a breaker 10 having a protruding shape is formed on the bottom surface portion 2B of the rake face 2, and the bottom surface portion 2B is slid as described above. By causing the contacted chips to collide with the breaker 10, it is possible to curl the chips more reliably and promote smoother chip treatment. Moreover, in this embodiment, the breaker 10 is formed in the shape of a ridge extending along the plane P that bisects the acute angle corner portion C. Therefore, the chips that collide with the breaker 10 are curled sideways. It is possible to reliably guide and discharge to the rear side in the feed direction without any problem.

  On the other hand, the breaker 10 does not exceed the inclined cutting edge 8 and the reverse inclined cutting edge 9 when viewed from the direction perpendicular to the plane P in which the protruding height in the thickness direction bisects the corner portion C. It is said to be high. For this reason, especially when turning stainless steel, it is possible to reliably prevent a situation in which the resistance when colliding with the breaker 10 becomes too large and the chips curl sideways.

  However, even if the breaker 10 is suppressed to a height that does not exceed the inclined cutting edge 8 and the reverse inclined cutting edge 9 as described above, for example, the inclined cutting edge 8 and the reverse inclined cutting edge 9 where the height of the cutting edge 6 is the lowest. If the protrusion 10A is formed perpendicularly to the thickness direction so that the breaker 10 has a constant height in accordance with the height of the intersection, the breaker 10 is in the plane P as in the present embodiment. Both ends of the breaker 10 with respect to the top T of the corner blade 7 that is the inclined cutting edge 8 and the cutting edge 6 that is the reverse inclined cutting edge 9 when formed in the shape of a ridge extending along There is a possibility that the height in the above thickness direction becomes too low, and the chip can be curled by giving sufficient resistance to the chips.

  For this reason, when the breaker 10 is formed in a ridge shape extending along the plane P in this way, when the protrusion 10A of the breaker 10 is also viewed from a direction orthogonal to the plane P, Along this plane P from the corner blade 7 side toward the inside of the rake face 2, it is inclined so as to gradually retreat in accordance with the inclined cutting edge 8, and then is inclined so as to gradually rise in accordance with the reverse inclined cutting edge 9. It is desirable that the height be set so as not to exceed the inclined cutting edge 8 and the reverse inclined cutting edge 9, whereby the height of the breaker 10 with respect to the cutting edge 6 can be made substantially constant and uniform resistance can be given to the chips. This makes it possible to stably curl the chips and achieve more reliable processing.

  In the present embodiment, the portion of the cutting edge 6 that slightly exceeds both ends S of the corner blade 7 is the inclined cutting edge 8, and the side farther from the corner blade 7 is the reverse inclined cutting edge 9. However, depending on, for example, the radius of the convex arc formed by the corner blade 7 in the plan view, the boundary (intersection) between the inclined cutting edge 8 and the reverse inclined cutting edge 9 is the opposite ends of the corner blade 7. It may be configured to be located in the part S, or may be formed so that the reverse inclined cutting edge 9 extends from the middle of the corner blade 7 having a convex arc shape in plan view. Further, the boundary between the inclined cutting edge 8 and the reverse inclined cutting edge 9 may be a concave curve with a small radius of curvature that is in smooth contact with the inclined cutting edge 8 and the reverse inclined cutting edge 9. The blade 6 may be subjected to honing with a very small width.

DESCRIPTION OF SYMBOLS 1 Insert body 2 Rake face 2A Positive rake face part 2B Bottom face part 3 Seating surface 4 Mounting hole 5 Relief face 6 Cutting edge 7 Corner blade 8 Inclined cutting edge 9 Reverse inclined cutting edge 10 Breaker 10A Top part 11 of breaker 10 Boss part 11C Boss Projection surface C of the section 11 Acute corner portion D Obtuse corner portion P Plane plane that bisects the acute corner portion C Q Plane plane that bisects the obtuse corner portion D R Projection end of the corner blade S S Top of reverse inclined cutting edge 9 α Inclination angle of inclined cutting edge 8 β Inclination angle of reverse inclined cutting edge 9

Claims (4)

  A corner blade having a convex arc shape in a plan view facing the rake surface is formed at a corner portion of the rake face of the insert body, and the corner blade is a protruding end of the convex arc formed by the corner blade in the plan view. As it goes from the part toward both ends, it is an inclined cutting edge that is inclined so as to gradually recede in the direction facing the rake face, and both ends of the corner blade have the above-mentioned at both ends in the plan view. A reverse inclined cutting edge extending in a tangential direction of the convex arc and inclined so as to gradually rise in a direction facing the rake face as it goes away from the end of the inclined cutting edge with respect to the corner blade. A cutting insert that is formed.   A flat seating surface is formed on the side opposite to the rake face of the insert body, and the tilt angle of the tilted cutting edge with respect to a plane parallel to the seating surface is in the range of 0 ° to 10 °, and 2. The cutting insert according to claim 1, wherein an inclination angle of the reverse inclined cutting edge is in a range of 0 ° to 10 °.   In the corner portion, the rake face includes a positive rake face part that gradually recedes from the periphery of the rake face toward the inside, and a bottom face part that continues to the positive rake face part, and the bottom face part has a projecting breaker. Is formed so as to have a height that does not exceed the inclined cutting edge and the reverse inclined cutting edge when viewed from a direction orthogonal to a plane that bisects the corner portion. Or the cutting insert of Claim 2.   The breaker has a ridge shape extending along a plane that bisects the corner portion, and when the top portion is viewed from a direction orthogonal to the plane, the rake face from the corner blade side. 4. Inclined so as to gradually recede in accordance with the inclined cutting edge toward the inner side, and then inclined so as to gradually rise in accordance with the reverse inclined cutting edge. Cutting insert as described in.

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