JP5939093B2 - Cutting insert set and cutting insert - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a cutting insert that is detachably attached to a cutting tool body that is replaceable with a cutting edge and includes a plurality of types of cutting inserts having different corner radii, and a cutting insert that constitutes the cutting insert set. It is.

  As such cutting inserts, in Patent Documents 1 to 3, a corner blade having a convex curve shape such as an arc is formed at a corner portion of a rake face of an insert body having a polygonal shape such as a parallelogram or a rectangle. In addition, there is described a cutting insert for a blade-tip-exchange-type end mill in which a main cutting edge and a secondary cutting edge are formed as cutting edges at the side ridges of the rake face continuous to both ends of the corner blade. The rake face is inclined so as to move away from the corner blade, the main cutting edge, and the sub cutting edge and gradually recede toward the inside of the insert body, and a positive rake angle is given to the corner cutting edge and the cutting edge. Has been.

  Among these, in the cutting insert described in Patent Document 1, a part of the corner blade and the main cutting blade extend on the same plane. Patent Documents 2 and 3 describe polishing the flank of the insert body that intersects the rake face via a corner blade and a cutting blade. Here, in order to smoothly connect the rake face of the main cutting edge and the auxiliary cutting edge inclined as described above, the rake face connected to the corner edge is generally in a cross section perpendicular to the bisector of the corner portion. The corner blade is formed so as to form a concave curve, and the rake face intersects with the flank on the one plane, so that the corner blade is formed as described above when viewed from the direction facing the rake face. It is formed in such a convex curve shape.

JP 2003-334716 A JP 2007-268641 A JP 2010-105134 A

  By the way, in such a cutting insert, there are a plurality of different corner radii, which are the radii of convex curves such as arcs formed by the corner blades, while maintaining the shapes and dimensions of the main cutting edge and the auxiliary cutting edge and the rake face and flank face. A cutting insert set consisting of various types of cutting inserts may be provided as a product lineup. The cutting inserts of such a cutting insert set can be attached to one type of end mill body, for example, in the case of the cutting insert for a blade-tip-exchangeable end mill as described above, and the bottom surface such as a groove formed in the work material. Cutting with a cutting insert having a different corner radius can be performed according to the radius of the corner between the wall and the wall.

  Here, the cutting insert as described above is usually compacted by compressing a raw material powder of a hard material such as cemented carbide or cermet with a press mold consisting of a die and a punch, and sintering the compact. Manufactured. For this reason, when manufacturing cutting inserts with different corner radii in this way, if the raw material powder is compressed for each cutting insert with different corner radii and manufactured from green compacts, the same number of press moldings as the types of corner radii are used. It is not economical because a mold is required.

  Therefore, in such a case, the cutting insert A having the smallest corner radius R1 in the cutting insert set as shown in FIG. 3 is manufactured by one type of press molding die, and used for cutting the cutting insert A. It is considered that the corner portion C is polished as described in Patent Documents 2 and 3 to produce a cutting insert B having a corner radius R2 larger than the corner radius R1 as shown in FIG. It is done.

  The cutting inserts A and B shown in FIG. 3 and FIG. 4 are cutting inserts for a blade-tip replaceable end mill as described in Patent Documents 1 to 3, and as described above, such as cemented carbide and cermet. A polygonal (substantially parallelogram) plate-shaped insert body 1 made of a hard sintered alloy has one polygonal surface as a rake surface 2, and the other polygonal surface is in the thickness direction of the insert body 1. (The vertical direction in each of FIGS. 3 and 4 in FIG. 3 and FIG. 4) is a flat surface that is a seating surface 3 on the end mill body of a blade tip replaceable end mill (not shown), and these polygonal surfaces A flank 4 is formed on the peripheral surface of the insert body 1 around the rake face 2 side. In addition, from the rake face 2 to the seating face 3, an attachment hole 5 through which a clamp screw for attaching the insert body 1 to the end mill body is inserted in the longitudinal direction of the parallelogram formed by the rake face 2 in these cutting inserts. Two, the insert body 1 is formed so as to penetrate in the thickness direction.

  At the intersecting ridge line portion of the rake face 2 and the flank face 4, a ¼ arc at the corner C of the parallelogram formed by the rake face 2 when viewed from the direction facing the rake face 2 in the thickness direction. A corner blade 6 having a convex curve shape such as the like is formed. At the both ends of the corner blade 6, a main cutting edge 7 is formed along the long side of the parallelogram, and a minor cutting edge 8 is formed on the short side. Is formed so as to be in contact with both ends of the corner blade 6. The main cutting edge 7 and the auxiliary cutting edge 8 are formed in a direction orthogonal to each other, and the short side of the parallelogram formed by the rake face 2 is bent at an obtuse angle opposite to the corner cutting edge 6 of the auxiliary cutting edge 8. It extends to the obtuse corner of the parallelogram.

  Further, as shown in FIGS. 3 (c) and 4 (c), the main cutting edge 7 moves away from the corner blade 6 and forms a convex curve as it goes toward the obtuse corner, and retreats in the thickness direction. It is formed to do. In contrast, in the cutting insert A having a small corner radius R1 shown in FIG. 3, the corner blade 6 and the sub-cutting blade 8 are located on one plane that protrudes most in the thickness direction and is perpendicular to the thickness direction. Has been. In both the cutting inserts A and B, the flank 4 is formed so as to incline toward the inner side of the insert body 1 as it goes from the rake face 2 side to the seating surface 3 side. The blade 6, the main cutting edge 7, and the auxiliary cutting edge 8 are positive inserts given clearance angles.

  Further, a portion around the mounting hole 5 at the center of the rake face 2 is formed in a planar shape perpendicular to the thickness direction that is recessed with respect to the corner blade 6, the main cutting edge 7, and the auxiliary cutting edge 8. Therefore, the corner rake face 2a connected to the corner edge 6 on the outer peripheral side of the rake face 2, the main rake face 2b connected to the main cutting edge 7, and the auxiliary rake face 2c connected to the auxiliary cutting edge 8 are It is inclined so as to gradually recede in the thickness direction toward the center, and a positive rake angle is given.

  Then, in order to smoothly connect the main rake face 2b and the sub rake face 2c which are inclined as described above, the corner rake face 2a is as viewed from the direction facing the rake face 2 in the thickness direction. In the cross section perpendicular to the bisector L of the corner portion C, it is formed so as to form a concave curve as described above, and is similarly inclined. Furthermore, in the cutting insert A shown in FIG. 3, the corner rake face 2 a intersects the flank 4 on the one plane, thereby forming the corner blade 6 having the convex curve as described above.

  A cutting insert set constituted by such cutting inserts A and B is formed by molding a green compact by one type of press mold corresponding to the cutting insert A in which the corner blade 6 has the smallest corner radius R1. Finally, if necessary, the flank 4 and, in some cases, the rake face 2 are also polished to produce a cutting insert A having a corner radius R1. Further, the cutting insert B is polished so that the flank 4 of the corner portion C of the sintered body manufactured in the cutting insert A is such that the corner blade 6 has a corner radius R2 larger than the corner radius R1. What is necessary is just to manufacture.

  However, when a cutting insert set composed of cutting inserts A and B having different corner radii R1 and R2 is manufactured in this way with reference to the cutting insert A having a small corner radius R1, the corner rake face 2a connected to the corner blade 6 is used. Is also formed on the basis of the small corner radius R1, and therefore when the cutting insert B having a large corner radius R2 is manufactured, the corner blade 6 having the large corner radius R2 is provided with a small corner radius R1. As shown in FIGS. 4C to 4E, the corner rake face 2a that forms a dent G is formed in the corner blade 6 in a side view. And in the part in which such a dent G was formed, since cutting edge strength was impaired, or a convex part was left behind in corners, such as a groove formed in a work material, processing accuracy was impaired. There is a risk that

  The present invention has been made under such a background, and when providing a cutting insert set including cutting inserts having different corner radii depending on one type of press mold, the cutting insert having the smallest corner radius is used as a reference. As a cutting insert set that can produce high cutting edge strength and processing accuracy with any corner radius cutting insert without producing the above-mentioned dent in the corner blade even when manufacturing a cutting insert with a large corner radius. And it aims at providing the cutting insert used as a standard in such a cutting insert set.

In order to solve the above-mentioned problems and achieve such an object, the cutting insert set of the present invention has a convex curved corner blade formed at the corner portion of the rake face forming the polygonal shape of the insert body, A cutting insert set comprising a plurality of types of cutting inserts formed with cutting edges extending in directions intersecting with each other at equal crossing angles at both ends of the corner blade, wherein the corner blade is provided on the rake face connected to the corner blade. positive rake angle is given to gradually retract in accordance away from Rutotomoni, rake face continuous with the corner cutting edge is perpendicular to the bisector of the corner portion when viewed from a direction facing the rake face in a cross section is formed so as to form a concave-curved, the cutting insert between the plurality of types is a corner radius are different sizes of the corner edge, intends this The rake face connected to the corner blade of the cutting insert having the smallest corner radius is inscribed in the cutting edge with a radius equal to the corner radius of the corner blade of the other cutting insert when viewed from the direction facing the rake face. The arc is formed so as to extend on one plane.

In the cutting insert of the present invention, a convex curved corner blade is formed at the corner portion of the rake face forming the polygonal shape of the insert body, and the rake face connected to the corner blade is separated from the corner blade. Rutotomoni given positive rake angle so as gradually retracted in accordance with, the rake face continuous with the corner cutting edge, in a cross section perpendicular to the bisector of the corner portion when viewed from a direction facing the rake face Is formed so as to form a concave curve , and the rake face connected to the corner blade is connected to cutting edges formed at both ends of the corner blade as viewed from the direction facing the rake face. An arc inscribed with a radius larger than the corner radius is formed so as to extend on one plane.

  Therefore, for example, in the above-mentioned cutting insert set in which such a cutting insert has the smallest corner radius as a reference, the rake face connected to the corner blade of the cutting insert having the smallest corner radius is opposed to the rake face. Since an arc inscribed in the cutting edge with a radius equal to the corner radius of the corner edge of the other cutting insert as viewed from the direction of extending is formed on one plane, the flank face along this arc When the other cutting insert having a large corner radius is manufactured by polishing, the arc that becomes the corner blade of the other cutting insert does not have a dent. For this reason, the cutting edge strength of the corner blade is not impaired in the recessed portion, and the convex portion is not left in the corner portion of the groove or the like formed in the work material. Can be planned.

  In the cutting insert set, the rake face connected to the corner blade of the cutting insert having the smallest corner radius is the corner radius of the corner blade of the other cutting insert as viewed from the direction facing the rake face. At the position of the arc inscribed in the cutting edge with an equal radius, the rake angle is discontinuously changed so as to increase toward the positive angle side toward the inside of the rake face away from the corner blade. Other cutting inserts having a larger corner radius increase the rake angle of the corner blade toward the positive side, thereby reducing the cutting resistance.

  On the other hand, also in the cutting insert, the rake face connected to the corner blade has a radius larger than the corner radius of the corner blade on the cutting edges formed at both ends of the corner blade as viewed from the direction facing the rake face. At the position of the inscribed arc, the rake angle is discontinuously changed so as to increase toward the positive side as it moves away from the corner blade and toward the inside of the rake face. Since the rake face is bent in a multistage shape, chip separation can be improved.

  As described above, according to the present invention, even when another cutting insert having a large corner radius is manufactured based on the cutting insert having the smallest corner radius in the cutting insert set, it is possible to prevent the corner blade from being recessed. The machining accuracy can be improved, and a cutting insert that serves as such a reference can be provided.

(A) Perspective view, (b) Top view, (c) Figure (b) showing one embodiment of the cutting insert with the smallest corner radius and the cutting insert of the present invention in one embodiment of the cutting insert set of the present invention It is a side view of the arrow line X direction view, (d) The side view of the arrow line Y direction view of FIG. (B), (e) The side view of the arrow line Z direction view of FIG. 1A is an enlarged plan view of a corner portion C in the cutting insert shown in FIG. 1, and FIG. 1B is another cutting insert having a corner radius next to the cutting insert shown in FIG. 1 in one embodiment of the cutting insert set of the present invention. FIG. 2C is an enlarged plan view of the corner portion C, and FIG. 2C is a corner portion C of another cutting insert having a radius next to the other cutting insert shown in FIG. 2B in the embodiment of the cutting insert set of the present invention. FIG. (A) perspective view, (b) plan view, (c) side view in the direction of arrow X in FIG. (B), (d) FIG. It is a side view of the arrow line Y direction view of b), (e) It is a side view of the arrow line Z direction view of FIG. FIG. 3A is a perspective view showing a cutting insert having a large corner radius among the conventional cutting insert sets manufactured based on the cutting insert shown in FIG. 3; FIG. It is a side view of the X direction view, (d) the side view of the arrow Y direction view of FIG. (B), (e) the side view of the arrow Z direction view of FIG.

  1 and 2 show an embodiment of a cutting insert set and a cutting insert according to the present invention. Among these, FIG. 1 and FIG. 2A show the cutting insert D having the smallest corner radius R10 and the cutting insert D of the present embodiment as a reference among the cutting insert sets of the present embodiment. 4 and the parts common to the cutting insert set and the cutting inserts A and B shown in FIG.

  The cutting insert D of the present embodiment is also a cutting insert for a blade edge type end mill, and the insert body 1 is formed in a polygonal (substantially parallelogram) plate shape by a hard sintered alloy such as cemented carbide or cermet. Yes. One of the polygonal surfaces of the insert body 1 is a rake face 2, and the other polygonal surface is perpendicular to the thickness direction of the insert body 1 (vertical direction in FIGS. 1C to 1E). A flat surface is used as a seating surface 3 on an end mill body (not shown), and a clearance surface 4 is formed on the rake face 2 side on the peripheral surface of the insert body 1 around these polygonal surfaces. Also, from the rake face 2 to the seating face 3, the mounting hole 5 through which the clamp screw for attaching the insert body 1 to the end mill body is inserted in the longitudinal direction of the parallelogram formed by the rake face 2 in this embodiment. That is, it is formed so as to penetrate the insert body 1 in the thickness direction.

  Further, at the intersecting ridge line portion between the rake face 2 and the flank face 4, the corner radius C of the parallelogram formed by the rake face 2 is set to the corner C of the parallelogram as viewed from the direction facing the rake face 2 in the thickness direction. A corner blade 6 having a convex curve shape such as a quarter arc of R10, for example, 0.4 mm is formed. Further, at both ends of the corner blade 6, as a cutting blade in the present embodiment, a main cutting edge 7 along the long side of the parallelogram, a sub cutting edge 8 along the short side, and a corner cutting edge 6. It is formed in contact with both ends. The main cutting edge 7 and the sub cutting edge 8 are formed in a direction orthogonal to each other, and the short side of the parallelogram formed by the rake face 2 is bent in an obtuse angle opposite to the corner cutting edge 6 of the sub cutting edge 8 and parallel to the parallel cutting edge. It extends to an obtuse corner of the quadrilateral.

  Further, as shown in FIG. 1 (c), the main cutting edge 7 has a convex curve shape toward the obtuse corner portion of the rake face 2 away from the corner blade 6 and is on the side of the seating face 3 in the thickness direction. It is formed to recede. Furthermore, in this embodiment, the sub-cutting blade 8 is also slightly retracted in the thickness direction as it is separated from the corner blade 6, and only the corner blade 6 protrudes most in the thickness direction and extends in the thickness direction. It is located on one vertical plane. Further, the flank 4 is inclined inward of the insert body 1 as it goes from the rake face 2 side to the seating face 3 side, and the cutting insert D of this embodiment is also the corner blade 6, the main cutting edge 7, and the auxiliary cutting edge. The blade 8 is a positive insert in which a clearance angle is given.

  Furthermore, the portion around the mounting hole 5 at the center of the rake face 2 is formed in a planar shape perpendicular to the thickness direction that is recessed with respect to the corner blade 6, the main cutting edge 7, and the auxiliary cutting edge 8. The portions of the rake face 2 except the corner rake face 2a, the main rake face 2b, and the auxiliary rake face 2c except for the periphery of the corner C are seated in the thickness direction toward the rake face 2 center. It is inclined so as to gradually recede toward the surface 3 side to give a positive rake angle.

  Here, the rake angle in the present embodiment is such that the corner blade 6, the main cutting edge 7, and the auxiliary cutting edge 8 are perpendicular to the corner blade 6, as viewed from the direction facing the rake face 2 in the thickness direction. The corner rake face 2a, the main rake face 2b, and the auxiliary rake face 2c form an angle with respect to a straight line that passes through the main cutting edge 7 and the auxiliary cutting edge 8 and is perpendicular to the thickness direction. The direction of retreating toward the seating surface 3 side in the thickness direction toward the central portion is the direction that increases toward the positive angle side.

  Further, in order to smoothly connect the main rake face 2b and the sub rake face 2c thus inclined, the corner rake face 2a is also viewed from the direction facing the rake face 2 in the thickness direction in this embodiment. The cross section perpendicular to the bisector L of the corner portion C is formed to have a concave curve shape.

  However, in this embodiment, as shown in FIG. 2 (a), the corner rake face 2a is connected to the corner rake face 2a in the thickness direction, as viewed from the direction facing the rake face 2 in the thickness direction. An arc inscribed in the main cutting edge 7 and the sub cutting edge 8 formed at both ends with a radius larger than the corner radius R1 of the corner blade 6 is formed so as to extend on one plane. In the present embodiment, the first and second plural (two) arcs 11 and 12 are formed, and each is positioned on one plane perpendicular to the thickness direction. The radius R11 of the inner first arc 11 is, for example, 0.8 mm, and the radius R12 of the second arc 12 further inside the first arc 11 is, for example, 1.2 mm, which is larger than the radius R11. .

  In the present embodiment, the rake angle of the corner rake face 2a is the thickness between the corner blade 6 and the first arc 11 and between the first arc 11 and the second arc 12. It is constant in the crescent-shaped region when viewed from the direction facing the rake face 2 in the direction, and is separated from the corner blade 6 at the position of the first and second arcs 11 and 12, and the rake face 2 ( The corner rake face 2a) is discontinuously changed so as to increase toward the regular angle side toward the inner side. That is, in the cross section along the bisector L, the corner rake face 2a forms a bent line shape that is convexly bent on the corner blade 6 side, and gradually retreats in the thickness direction toward the center side of the rake face 2. Has been.

  Therefore, in the present embodiment, the one plane where the first arc 11 is located is disposed at a position retracted toward the seating surface 3 in the thickness direction than the one plane where the corner blade 6 is located. The one plane on which the second arc 12 is located is disposed at a position further retracted toward the seating surface 3 in the thickness direction than the one plane on which the first arc 11 is located. The main cutting edge 7 and the auxiliary cutting edge 8 are extended in a very short range at both ends of the crescent-shaped region between the corner blade 6 and the first and second arcs 11 and 12. In this extremely short range, the main rake face 2b and the sub rake face 2c connected to the main cutting edge 7 and the auxiliary cutting edge 8 are also formed in the crescent-shaped region.

  And in the cutting insert set of this embodiment, the position of these 1st, 2nd circular arcs 11 and 12 turns into the position of the corner blade 6 of the other cutting inserts E and F from which the corner radius differs from the cutting insert D. . Therefore, as shown in FIG. 2B, the corner radius R11 of the corner blade 6 in the other first cutting insert E is set to 0.8 mm, and the other second cutting insert as shown in FIG. 2C. The corner radius R12 of the corner blade 6 at F is 1.2 mm. That is, the cutting insert set of this embodiment is a set of three types of cutting inserts D, E, and F having different corner radii.

  Such other cutting inserts E and F are manufactured by polishing the flank 4 to the positions of the first and second arcs 11 and 12 with the cutting insert D as a reference. If the flank 4 of the corner portion C of the reference cutting insert D is ground to the position of the first arc 11, another first cutting insert E can be manufactured, up to the position of the second arc 12. If polishing is performed, another second cutting insert F can be manufactured. Therefore, in the cutting inserts D, E, and F of the cutting insert set of the present embodiment, the main cutting edge 7 and the auxiliary cutting edge 8 both extend in a direction intersecting at an equal crossing angle (right angle), and the corner portion. The portions other than the periphery of C are assumed to be the same shape and size.

  According to such a cutting insert set and the cutting insert D, the first and second different corners are used by using one type of press mold for manufacturing the cutting insert D having the smallest corner radius R10 as a reference. Cutting inserts E and F having radii R11 and R12 can be manufactured. For this reason, it is not necessary to prepare a press-molding die for each of the cutting inserts D, E, and F having the corner radii R10, R11, and R12, which is economical and efficient.

  Further, in the cutting insert set and the cutting insert D having the above-described configuration, in a portion connected to the corner blade 6 of the rake face 2, a radius larger than the corner radius R <b> 10 of the corner blade 6 as viewed from the direction facing the rake face 2, In the present embodiment, first and second arcs 11 and 12 having the same radius as the corner radii R11 and R12 of the corner blades 6 of the other first and second cutting inserts E and F are formed. Each of the second arcs 11 and 12 extends on one plane.

  For this reason, even when the first and second cutting inserts E and F are manufactured by polishing the flank 4 as described above, the corner blades 6 of these other cutting inserts E and F are each one of the above-mentioned ones. In other words, the dent G as shown in FIG. 4 does not occur in the corner blade 6. Accordingly, the cutting edge strength of the corner blade 6 is not impaired by such a recess G, and the other first and second cutting inserts E and F are attached to the end mill body of the blade edge replaceable end mill. When performing grooving or the like, high-precision cutting can be performed without leaving a convex portion due to the dent G at the corner between the bottom surface and the wall surface of the groove formed in the work material. In addition, it is possible to provide a cutting insert D serving as a reference for such other first and second cutting inserts E and F.

  Furthermore, in the cutting insert set of the present embodiment, the corner rake face 2a connected to the corner blade 6 is the first and second arcs 11 that become the corner blade 6 in the other first and second cutting inserts E and F described above. , 12, the rake angle is discontinuously changed so as to increase toward the positive angle side toward the inside of the rake face 2 away from the corner blade 6. For this reason, the rake angle of the first cutting insert E having a larger corner radius R11 is larger than that of the reference cutting insert D having the smallest corner radius R10, and is larger than that of the first cutting insert E. The second cutting insert F having a larger corner radius R12 has a larger rake angle, and a cutting insert having a larger corner radius and a longer cutting edge length has a higher rake angle. Therefore, the cutting resistance can be reduced.

  Further, also in the cutting insert D and the other first cutting insert E serving as the reference of the present embodiment, the rake angle of the corner rake face 2a changes discontinuously, and the corner rake along the bisector L is described above. As described above, the cross section of the surface 2a has a broken line shape that bends at the positions of the arcs 11 and 12. For this reason, the chips generated by the corner blade 6 and scraped on the corner rake face 2a are easily separated from the corner rake face 2a when passing through the positions of the arcs 11 and 12, so that the so-called chip separation is improved. Also, the effect of reducing the cutting resistance can be obtained.

  However, in this embodiment, the rake angle of the corner rake face 2a connected to the corner blade 6 is changed discontinuously as described above, and the arcs 11 and 12 are formed on the corner rake face 2a. The rake line is formed as a ridge line formed by connecting the bending points of the rake line, but the rake angle is separated from the corner blade 6 and continuously increases toward the positive angle side toward the inner side of the rake face 2. It may be changed. In this case, the arcs 11 and 12 are not formed as ridge lines on the corner rake face 2a, but the arcs inscribed in the main cutting edge 7 and the sub-cutting edge 8 with a radius larger than that of the corner edge 6 are formed in the corner rake face 2a. When drawn above, this arc is located on one plane for each radius.

  In the present embodiment, the corner blades 6 of the cutting inserts D, E, and F and the arcs 11 and 12 that become the corner blades 6 of the other cutting inserts E and F are arranged on a single plane perpendicular to the thickness direction of the insert body 1. For example, from the intersection of the corner blade 6 and the bisector L when viewed from the direction facing the rake face 2 in the thickness direction, that is, from the tip of the corner blade 6, this second Corner blades 6 and arcs 11 and 12 are positioned on each inclined plane inclined toward the seating surface 3 side in the thickness direction as it goes inward of the rake face 2 along the dividing line L. It may be.

  Furthermore, although the cutting insert set of this embodiment is comprised by three types of cutting inserts D, E, and F from which a corner radius differs, a cutting insert set is comprised by four or more types of cutting inserts, or cutting insert D , E and cutting inserts D and F may be combined to form a cutting insert set. Moreover, the cutting insert set may be comprised by the combination with the other cutting insert F by using the cutting insert E as a reference | standard cutting insert.

D Cutting insert E, F Other cutting inserts 1 Insert body 2 Rake face 2a Corner rake face 2b Main rake face 2c Sub rake face 3 Seating face 4 Relief face 5 Mounting hole 6 Corner blade 7 Main cutting edge (both ends of corner blade 6) Cutting blades connected to
8 Sub cutting edge (cutting edge connected to both ends of corner blade 6)
11, 12 Arcs inscribed in the cutting edges 7, 8 at the same radius as the corner radii R11, R12 of the corner cutting edges 6 of the other cutting inserts E, F C Corner portion L Disection line of the corner portion C R10 of the cutting insert D Smallest corner radius R11, R12 Corner radius of other cutting inserts E, F

Claims (4)

Convex-curved corner blades are formed at the corner portion of the rake face forming the polygonal shape of the insert body, and plural types of cutting blades extending in directions intersecting at equal crossing angles are formed at both ends of the corner blade. a cutting insert set consisting of the cutting insert, gradually receding positive rake angle is given to Rutotomoni, salvation connected to the corner cutting edge according to the rake face connected to the corner cutting edge away from the corner cutting edge The surface is formed so as to form a concave curve in a cross section perpendicular to the bisector of the corner portion when viewed from the direction facing the rake face, The corner radii of the corner blades are of different sizes, and of these, the rake face connected to the corner blade of the cutting insert with the smallest corner radius is the rake face. An arc inscribed in the cutting blade with a radius equal to the corner radius of the corner blade of another cutting insert as viewed from the direction facing the surface is formed to extend on one plane. Cutting insert set.   The rake face connected to the corner blade of the cutting insert having the smallest corner radius is inscribed in the cutting edge at a radius equal to the corner radius of the corner edge of the other cutting insert as viewed from the direction facing the rake face. 2. The position of the arc is discontinuously changed so that the rake angle increases toward the positive angle side as the distance from the corner blade increases toward the inside of the rake face. Cutting insert set. Convex-curved corner blades are formed at the corners of the polygonal rake face of the insert body, and the rake faces continuous with the corner blades are positively raked so as to gradually recede as they are separated from the corner blades. Rutotomoni corners given rake face connected to the corner cutting edge is formed so as to form a concave curved shape in a cross section perpendicular to the bisector of the corner portion when viewed from a direction facing the rake face It is, in the rake face continuous with the corner cutting edge, inscribed with greater than the radius corner radius of the corner cutting edge to the cutting edge formed at both ends of the corner edge as viewed from a direction facing the rake face A cutting insert characterized in that an arc is formed so as to extend on one plane.   The rake face connected to the corner blade is located at the position of the arc inscribed in the cutting edges formed at both ends of the corner blade with a radius larger than the corner radius of the corner blade as viewed from the direction facing the rake face. 4. The cutting insert according to claim 3, wherein the rake angle is discontinuously changed so as to increase toward the positive angle side as the distance from the corner blade increases toward the inside of the rake face.

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