JP6236594B1 - Cutting insert - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting insert capable of preventing damage such as chipping of a cutting edge. A cutting insert according to the present invention includes a first end face 2, a second end face 3 facing the first end face 2, and a peripheral side face connecting the first end face 2 and the second end face 3. 4, a cutting insert having a cutting edge 5 at a crossing ridge line portion between the first end surface 2 and the peripheral side surface 4, wherein the first end surface 2 includes at least one corner portion 6 a, a center surface 9, And a concave chip breaker groove 8 surrounding the central surface 9. The cutting edge 5 includes a first cutting edge 5a at the corner 6a, and a second cutting edge that is spaced apart from the second end face 3 from the first cutting edge 5a and substantially parallel to the second end face 3. Part 5b. The first end surface 2 has a land 7a along the second cutting edge portion 5b. [Selection] Figure 1

Description

  The present invention relates to a cutting insert that is detachably mounted on a cutting tool and used for cutting a metal material or the like.

  There exists a thing as shown in patent document 1 in the conventional cutting insert. The cutting insert of Patent Document 1 is a cutting insert having two end faces facing each other, a peripheral side face connecting these end faces, and a cutting edge at a cross ridge line portion between each end face and the peripheral side face. Has a central surface in the central region, a strip-like land along the cutting edge, and a concave chip breaker groove. The land is arranged at the same height as the center plane. That is, the land becomes a contact surface (grounding surface) with the insert mounting portion of the cutting tool together with the center surface.

JP 2004-276195 A

  In the cutting insert of Patent Document 1, since the land connected to the cutting edge comes into contact with the insert mounting portion of the cutting tool, there is a certain effect of preventing damage such as chipping of the cutting edge in machining under a cutting condition with a large impact. is there. However, since the entire circumference of the land connected to the cutting edge comes into contact with the insert mounting portion, if the land after the cutting edge and the land are used is used as a contact surface, the contact is caused by damage such as wear or deposits. There is a problem that the state becomes unstable and the cutting performance is not stable. Further, as in the cutting insert of Patent Document 1, when the protrusion is extended from the center surface toward the cutting edge, there is a problem that cutting of cutting conditions is limited by the protrusion.

  The cutting inserts 1 and 20 of the present invention include a first end surface 2, a second end surface 3 that faces the first end surface 2, and a peripheral side surface 4 that connects the first end surface 2 and the second end surface 3. And cutting inserts 1 and 20 having a cutting edge 5 at a crossing ridge line portion between the first end surface 2 and the peripheral side surface 4, wherein the first end surface 2 includes at least one corner portion 6 a and a central surface 9. And a concave chip breaker groove 8 surrounding the central surface 9. The cutting edge 5 includes a first cutting edge 5a at the corner 6a, and a second cutting edge that is spaced apart from the second end face 3 from the first cutting edge 5a and substantially parallel to the second end face 3. Part 5b. The first end surface 2 has a land 7a along the second cutting edge portion 5b.

It is a perspective view of the cutting insert concerning a 1st embodiment. It is a top view of the cutting insert of FIG. It is a right view of the cutting insert of FIG. It is a perspective view of the cutting insert which concerns on 2nd Embodiment. It is a top view of the cutting insert of FIG. It is a right view of the cutting insert of FIG. It is a table | surface of a 1st experimental result. It is a table | surface of the 2nd experimental result. It is a table | surface of the 3rd experimental result. It is a table | surface of a 4th experimental result. It is a table | surface of the 5th experimental result.

  Cutting inserts 1 and 20 according to an embodiment of the present invention will be described with reference to the drawings. The cutting inserts 1 and 20 are suitable for lathe processing.

  First, the cutting insert 1 which concerns on 1st Embodiment is demonstrated. As shown in FIGS. 1 to 3, the cutting insert 1 has a substantially rhomboid plate shape. That is, the cutting insert 1 has two substantially rhombic end faces 2 and 3 that face each other, and a peripheral side face 4 that connects the two end faces 2 and 3. This approximately rhombus has two 80 ° corners and two 100 ° corners. Here, of the two end surfaces 2 and 3, the first end surface 2 is referred to as the upper surface 2, and the second end surface 3 is referred to as the lower surface 3. In addition, although the term showing the direction in space, such as an upper surface, is used for the sake of convenience, it is not intended to define an absolute direction or positional relationship in the space. Unless otherwise noted, the same applies to terms representing orientations and positional relationships in other spaces.

  The upper surface 2 has a corner portion 6 that curves to a corner of 80 °. The upper surface 2 has a corner portion 6 that curves even at a 100 ° corner. The intersecting ridge line portion between the upper surface 2 and the peripheral side surface 4 has a cutting edge 5. The upper surface 2 has a concave chip breaker groove 8. A land 7 is provided between the cutting edge 5 and the chip breaker groove 8. The cutting edge 5 has a corner cutting edge corresponding to the corner portion 6 of the 80 ° corner, and a pair of straight cutting edges extending from the corner cutting edge. The cutting insert 1 also has a corner cutting edge at a corner portion 6 of a 100 ° corner. That is, the cutting insert 1 can use the entire circumference of the intersecting ridge line portion between the upper surface 2 and the peripheral side surface 4 as the cutting edge 5. The radius of curvature of the corner cutting edge of the cutting insert 1 is about 0.8 mm.

  The shape of the cutting insert 1 is 180 ° rotationally symmetric with respect to a reference axis A passing through the upper surface 2 and the lower surface 3. That is, the upper surface 2 and the lower surface 3 are two-fold rotationally symmetric. Further, the shape of the cutting insert 1 is mirror-image symmetric with respect to the bisector of each corner portion 6. The cutting insert 1 has a mounting hole 10 that passes through the center of each of the upper surface 2 and the lower surface 3. The central axis of the attachment hole 10 coincides with the reference axis A. The diameter of the mounting hole 10 is about 3.8 mm. The upper surface 2 has a substantially flat central surface 9 in the central region around the mounting hole 10. The lower surface 3 also has a substantially flat central surface 9 in the central region around the mounting hole 10. The chip breaker groove 8 separates the center surface 9 of the upper surface 2 from the land 7. That is, the chip breaker groove 8 surrounds the central surface 9 of the upper surface 2. The chip breaker groove 8 is formed over the entire circumference along the cutting edge 5 of the upper surface 2. The diameter of the inscribed circle dimension B of the approximately rhombus on the upper surface 2 is about 9.5 mm. The upper surface 2 is substantially parallel to the lower surface 3. The distance between the central surface 9 on the upper surface of the cutting insert 1 and the central surface 9 on the lower surface is about 4 mm.

  The peripheral side surface 4 connected to the cutting edge 5 functions as a flank. The flank of the cutting insert 1 is orthogonal to the upper surface 2 and the lower surface 3. The cutting insert 1 is called a so-called negative type. The cutting insert 1 can be used on both sides by turning the upper surface 2 and the lower surface 3 upside down. That is, the cutting insert 1 has the cutting edge 5 also on the lower surface 3 side. As described above, the upper surface 2 and the lower surface 3 are two-fold rotationally symmetric. That is, the upper surface 2 and the lower surface 3 each have two cutting edges 5. Therefore, the cutting insert 1 can be used at least four times because the cutting edge 5 on the upper surface 2 side can be used at least twice and the cutting edge 5 on the lower surface 3 side can be used at least twice. Hereinafter, only the upper surface 2 side will be described in order to simplify the description. The lower surface 3 side has the same shape as the upper surface 2 side. Moreover, since the upper surface 2 has a two-fold rotational symmetry, only one side will be described. The other side of the upper surface 2 has the same shape as the one side.

  As shown in FIG. 3, when the cutting edge 5 is viewed from the direction facing the peripheral side surface 4, the height of the cutting edge 5 on the upper surface 2 from the lower surface 3 side changes. Here, one of the 80 ° corners on the upper surface 2 side is referred to as a first corner portion 6a. Specifically, in FIG. 2, the lower corner is defined as a first corner portion 6a. Here, the cutting edge part of the 1st corner part 6a among the cutting edges 5 of the upper surface 2 is called the 1st cutting edge part 5a. As shown in FIG. 3, the cutting edge 5 on the upper surface 2 has a second cutting edge portion 5 b that is separated from the lower surface 3 than the first cutting edge portion 5 a and extends substantially parallel to the lower surface 3. The second cutting edge portion 5b is located on a virtual plane obtained by extending the central surface 9 of the upper surface 2. When viewing the cutting edge 5 from the direction facing the peripheral side surface 4, the cutting edge 5 on the upper surface 2 has a third cutting edge portion 5 c that is separated from the lower surface 3 side as it is separated from the first corner portion 6 a, and the lower surface 3. And a fourth cutting edge portion 5d connected to the first cutting edge portion 5a.

  Here, a portion of the land 7 that is connected to the second cutting edge portion 5b is referred to as a contact land portion 7a. The contact land portion 7 a extends from the second cutting edge portion 5 b in a direction orthogonal to the peripheral side surface 4. That is, the contact land portion 7 a is disposed on a virtual plane that is an extension of the central surface 9 of the upper surface 2.

  Materials around the cutting edge 5 of the cutting insert 1 are hard materials such as cemented carbide, cermet, ceramic, sintered body containing cubic boron nitride, sintered body containing diamond, or the like of these hard materials. It is preferably selected from those obtained by coating the surface with a coating film by PVD or CVD. Moreover, it is preferable that the material of parts other than the periphery of the cutting edge 5 is also the same hard material.

  The cutting insert 1 having the above-described configuration is detachably mounted on an insert mounting portion of a tool body (a lathe holder) of a cutting tool using a clamp member that is a mechanical mounting means. Various known tool bodies can be applied to the tool body. As the clamp member, various known clamp members such as a lever and a pressing member can be applied. The cutting tool to which the cutting inserts 1 and 20 of the present invention are attached is attached to a machine tool such as a lathe, and is provided with rotation and feed operations relative to the workpiece, for cutting metal and the like. Available.

  Next, the cutting insert 20 according to the second embodiment will be described with reference to the drawings. The description of the cutting insert 20 is only the main differences from the cutting insert 1 in the first embodiment, and the same reference numerals are assigned to the components common to the cutting insert 1 and description thereof is omitted.

  As shown in FIGS. 4 to 6, the cutting insert 20 has a substantially triangular plate shape. That is, it has the substantially triangular upper surface 2 and lower surface 3 facing each other, and the peripheral side surface 4 connecting the upper surface 2 and the lower surface 3. The upper surface 2 and the lower surface 3 are substantially equilateral triangles.

  The intersecting ridge line portion between the upper surface 2 and the peripheral side surface 4 has a cutting edge 5. The cutting insert 20 can use the entire circumference of the intersecting ridge line portion between the upper surface 2 and the peripheral side surface 4 as the cutting edge 5. The upper surface 2 has a concave chip breaker groove 8. A land 7 is provided between the cutting edge 5 and the chip breaker groove 8. The cutting insert 20 is 120 ° rotationally symmetric with respect to a reference axis A that penetrates the upper surface 2 and the lower surface 3. That is, the upper surface 2 and the lower surface 3 of the cutting insert 20 are rotationally symmetrical three times. Further, the shape of the cutting insert 1 is mirror-image symmetric with respect to the bisector of each corner portion 6. The cutting insert 1 has a mounting hole 10 that passes through the center of each of the upper surface 2 and the lower surface 3. The central axis of the attachment hole 10 coincides with the reference axis A. The diameter of the mounting hole 10 is about 2.4 mm. The radius of curvature of the corner cutting edge of the cutting insert 20 is about 0.8 mm. The diameter of the inscribed circle dimension B of the substantially equilateral triangle on the upper surface 2 is about 6.4 mm. The distance between the central surface 9 of the upper surface 2 of the cutting insert 20 and the central surface 9 of the lower surface 3 is about 4 mm.

  The cutting insert 1 can be used on both sides by turning the upper surface 2 and the lower surface 3 upside down. That is, the cutting insert 1 has the cutting edge 5 also on the lower surface 3 side. The cutting insert 20 can be used at least six times because the cutting edge 5 on the upper surface 2 side can be used at least three times and the cutting edge 5 on the lower surface 3 side can be used at least three times. Hereinafter, only the upper surface 2 side will be described in order to simplify the description. The lower surface 3 side has the same shape as the upper surface 2 side. Here, one of the corners on the upper surface 2 side is referred to as a first corner portion 6a. Specifically, in FIG. 5, the lower corner is defined as a first corner portion 6a. As described above, since the upper surface 2 is 120 ° rotationally symmetric, only the periphery of the first corner portion 6a will be described. The periphery of the other two corner portions 6 of the upper surface 2 has the same shape as the periphery of the first corner portion 6a.

  As shown in FIG. 6, when the cutting edge 5 is viewed from the direction facing the peripheral side surface 4, the height of the cutting edge 5 from the lower surface 3 side changes. Of the cutting edges 5 on the upper surface 2, the cutting edge portion of the first corner portion 6a is referred to as a first cutting edge portion 5a. The cutting edge 5 on the upper surface 2 has a second cutting edge portion 5 b that is separated from the lower surface 3 than the first cutting edge portion 5 a and extends substantially parallel to the lower surface 3. The second cutting edge portion 5b is located on a virtual plane obtained by extending the central surface 9 of the upper surface 2. When viewing the cutting edge 5 from the direction facing the peripheral side surface 4, the cutting edge 5 on the upper surface 2 has a third cutting edge portion 5 c that is separated from the lower surface 3 side as it is separated from the first corner portion 6 a, and the lower surface 3. And a fourth cutting edge portion 5d connected to the first cutting edge portion 5a.

  Here, a portion of the land 7 that is connected to the second cutting edge portion 5b is referred to as a contact land portion 7a. The contact land portion 7 a extends from the second cutting edge portion 5 b in a direction orthogonal to the peripheral side surface 4. Therefore, the contact land portion 7 a is disposed on a virtual plane obtained by extending the central surface 9 of the upper surface 2.

  The operation and effect of the cutting inserts 1 and 20 described so far will be described below. In addition, below, the preferable form of the cutting inserts 1 and 20 is also demonstrated.

  The contact land portions 7a of the cutting inserts 1 and 20 are arranged on a virtual plane obtained by extending the central surface 9. For this reason, the contact land part 7a and the center surface 9 of the cutting inserts 1 and 20 can be made into a contact surface with the insert attachment part of the tool body of a cutting tool. In particular, when the area of the center surface 9 is narrow, such as when the chip breaker groove 8 is wider than the inscribed circle size B of the cutting inserts 1 and 20, the contact land portion 7a is also used as the contact surface. Is effective. For example, it is particularly suitable for small cutting inserts whose inscribed circle dimension B is less than 10 mm. In the cutting insert 1 and the cutting insert 20, the contact land portion 7a is a flat surface parallel to the lower surface 3. However, the present invention is not limited to this. The contact land portion 7a may have any shape as long as it can contact the insert mounting portion together with the center surface 9. That is, the center surface 9 and the contact land portion 7a may have a shape corresponding to the seat surface of the insert mounting portion. The seat surface of the insert mounting portion preferably has a simple shape such as a virtual surface obtained by extending the central surface 9. When the seat surface of the insert mounting portion is such a surface, the contact land portion 7a can be easily contacted with the contact land 7a if the portion farthest from the lower surface 3 is disposed on a virtual surface extending the central surface 9. A part of the part 7 a can be brought into contact with the central surface 9. When the center surface 9 is a substantially flat surface, it is preferable that the part most distant from the lower surface 3 of the contact land portion 7 a is disposed on a virtual plane extending the center surface 9. In addition, like the cutting inserts 1 and 20, the center surface 9 is a substantially flat surface, the contact land portion 7a is also a substantially flat surface, and the contact land portion 7a is disposed on a virtual plane extending the center surface 9. More preferably.

  The cutting edge 5 and the land 7 may be worn during the cutting process or may be attached with a deposit. As described above, if the entire circumference of the land 7 is a contact surface, the contact state becomes unstable when the used land 7 is turned over to be the contact surface, and the cutting performance is deteriorated. In particular, when the land portion in the vicinity of the corner portion 6 is damaged, the cutting performance when turned over is greatly deteriorated. Therefore, the land portion in the vicinity of the corner portion 6 is not used as a contact surface, and only the contact land portion 7a separated from the corner portion 6 is caused to function as the contact surface, so that the cutting performance is improved. In particular, in turning of cast iron, it is effective to allow only the contact land portion 7a to function as the contact surface.

  When the second cutting edge 5b is viewed from the direction facing the peripheral side surface 4, the first cutting edge 5a is formed on the first corner portion 6a, and the lower surface 3 from the first cutting edge portion 5a. Having the second cutting edge portion 5b that is spaced apart from the surface and substantially parallel to the lower surface 3 also has an effect of reducing cutting resistance. In the chip breaker groove 8 for processing chips during cutting, the height of the wall surface with respect to the cutting edge 5 is important. When the cutting depth is small, it may be better that the wall surface of the chip breaker groove 8 is high. In other words, the first cutting edge 5a in the vicinity of the corner portion 6 may be preferably closer to the lower surface 3 (that is, lower). When the depth of cut is large, if the wall surface of the chip breaker groove 8 is high, the cutting resistance increases abruptly, which may not be preferable. In other words, the abutting cutting edge portion 5b that is away from the corner portion 6 may be better away (that is, higher) from the lower surface 3 side. Therefore, when the height of the cutting edge 5 is changed like the cutting inserts 1 and 20, it is possible to improve chip controllability while reducing cutting resistance. The first cutting edge 5a and the contact cutting edge 5b can be connected with various shapes of the cutting edges 5. The cutting inserts 1, 20 have a fourth cutting edge portion 5 d that is connected to the first cutting edge portion 5 a and is substantially parallel to the lower surface 3. Since the 4th cutting edge part 5d is made into the same height as the 1st cutting edge part 5a, the chip disposal property when the cutting of cutting conditions is small is excellent. The 4th cutting blade part 5d and the 2nd cutting blade part 5b are connected via the 3rd cutting blade part 5c from which height changes. The cutting inserts 1 and 20 have corners at the connection between the second cutting edge 5b and the third cutting edge 5c. However, the present invention is not limited to this, and the second cutting edge 5b and the third cutting edge 5c may be smoothly connected.

  As shown in FIGS. 2 and 5, the width D of the land 7 from the second cutting edge 5 b when viewed from the direction facing the upper surface 2 is referred to as a land width D. FIG. 7 shows a first experimental result regarding the width D of the land. In the first experiment, a cutting insert having a land width D different from that of the cutting insert 1 is manufactured, and a cast iron (FC250) workpiece having a groove to be intermittently cut is subjected to the following cutting conditions. The tool life was compared by observing the wear state of each cutting insert. The cutting conditions were a cutting length of about 50 mm from the outer periphery toward the center of the end surface of the workpiece, a cutting speed of 500 m / min, a cutting depth of 2 mm, a feed of 0.4 mm / rev, and wet cutting. Judgment of tool life uses two cutting inserts, finds the average tool life of all cutting edges 5 (that is, 8 times), and sets the tool life of the longest cutting insert as 100% of the standard. A tool life of 90% or more and 100% or less was judged as A, 75% or more and less than 90% as B, 50% or more and less than 75% as C, and less than 50% as D. The land width D is preferably 0.15 mm or more and 0.5 mm or less. In particular, the width of the contact land portion 7a is preferably 0.15 mm or more and 0.5 mm or less. When the land width D is less than 0.15 mm, the function as the contact surface becomes insufficient, and the cutting performance becomes unstable. When the land width D exceeds 0.5 mm, the cutting resistance increases, and the functions of the cutting edge 5 and the chip breaker groove 8 are rapidly lowered. The land widths D of the cutting insert 1 and the cutting insert 20 are both about 0.3 mm. The width of the portion that does not function as the contact surface of the land 7 may be appropriately adjusted according to the work material and cutting conditions.

  As shown in FIG. 3, when the cutting edge 5 is viewed from the direction facing the peripheral side surface 4, the height difference E from the lower surface 3 side between the second cutting edge portion 5 b and the first corner portion 6 a is determined as the height difference E. It is called. FIG. 8 shows a second experimental result regarding the height difference E. As shown in FIG. In the second experiment, cutting inserts having different height differences E with respect to the cutting insert 1 were produced, and the tool life was compared. Other experimental conditions were the same as those in the first experiment described above. The height difference E is preferably 0.03 mm or more and 1 mm or less. When the height difference E is less than 0.03 mm, if there is a deposit, the cutting performance is rather unstable. When the height difference E exceeds 1 mm, chips are likely to enter the gap during cutting, and the cutting edges 5 or lands 7 on the unused lower surface 3 may be damaged. When the damaged cutting edge 5 was used, the tool life was deteriorated. The height difference E between the cutting insert 1 and the cutting insert 20 is about 0.1 mm.

  As shown in FIGS. 2 and 5, the dimension F from the second cutting edge 5b to the farthest part of the first corner 6a along the direction in which the second cutting edge 5b extends is set to be long. This is called F. FIG. 9 shows a third experimental result regarding the length F. In FIG. In the third experiment, cutting inserts having different lengths F from the cutting insert 1 were produced, and the tool life was compared. Other experimental conditions were the same as those in the first experiment described above. The length F is preferably 2 mm or more and 7 mm or less. As described above, when the cutting depth is small, the height of the wall surface of the chip breaker groove 8 may be better. When the length F is less than 2 mm, the length of the high wall surface is insufficient, and chip disposal when the cut is small is difficult. When the length F exceeds 7 mm, the distance of the contact land portion 7a from the first corner portion 6a becomes too long, and the effect of using the contact land portion 7a as the contact surface is rapidly reduced. The length F is more preferably 3 mm or more and 6 mm or less. The lengths F of the cutting insert 1 and the cutting insert 20 are both about 4 mm.

  The preferred dimension of the length F is also related to the inscribed circle dimension B. FIG. 10 shows a fourth experimental result regarding the ratio of the length F to the inscribed circle dimension B. In the fourth experiment, cutting inserts having different lengths F were prepared with respect to the cutting insert 1 having a substantially rhombic upper surface 2 according to the first embodiment of FIG. Other experimental conditions were the same as those in the first experiment described above. When the upper surface 2 is substantially rhombus like the cutting insert 1, the dimension F is preferably 20% or more and 70% or less with respect to the diameter of the inscribed circle dimension B. Although not shown, when the upper surface 2 is substantially hexagonal, the dimension F is preferably 20% or more and 70% or less with respect to the diameter of the inscribed circle dimension B. When the length F is less than 20% with respect to the inscribed circle dimension B, the length of the portion with the high wall surface is insufficient, and chip disposal when the cut is small is difficult. When the length F exceeds 70% with respect to the inscribed circle dimension B, the distance of the contact land portion 7a from the first corner portion 6a becomes too long, so the contact land portion 7a is used as the contact surface. The effect drops rapidly. The ratio of the length F to the inscribed circle dimension B is more preferably 30% or more and 60% or less. The ratio of the length F of the cutting insert 1 to the inscribed circle dimension B is about 40%.

  FIG. 11 shows the fifth experimental result relating to the ratio of the length F to the inscribed circle dimension B. In the fifth experiment, cutting inserts having different lengths F were prepared for the cutting insert 20 having a substantially triangular upper surface 2 according to the second embodiment shown in FIG. Judgment of tool life uses two cutting inserts, finds the average tool life of all cutting edges 5 (that is, 12 times), and sets the tool life of the longest cutting insert as 100% of the standard. A tool life of 90% or more and 100% or less was judged as A, 75% or more and less than 90% as B, 50% or more and less than 75% as C, and less than 50% as D. Other experimental conditions were the same as those in the first experiment described above. When the upper surface 2 is substantially triangular like the cutting insert 20, the dimension F is preferably 40% or more and 90% or less with respect to the diameter of the inscribed circle dimension B. When the length F is less than 40% with respect to the inscribed circle dimension B, the length of the portion having a high wall surface is insufficient, and chip disposal when the cut is small is difficult. If the length F exceeds 90% with respect to the inscribed circle dimension B, the distance of the contact land portion 7a from the first corner portion 6a becomes too long, so the contact land portion 7a is used as the contact surface. The effect drops rapidly. The ratio of the length F to the inscribed circle dimension B is more preferably 50% or more and 80% or less. The ratio of the length F of the cutting insert 20 to the inscribed circle dimension B is about 60%.

  As described above, the cutting inserts 1 and 20 can have the cutting edge 5 on the entire circumference of the intersecting ridge line portion between the upper surface 2 and the lower surface 3 and the peripheral side surface 4. There is no restriction on the shape of the chip breaker groove 8, and the cutting of the cutting conditions is not limited. That is, the chip breaker groove 8 can also be arranged at a portion connected to the contact land portion 7a. The chip breaker groove 8 is preferably arranged along the entire cutting edge 5 along the entire circumference. When the chip breaker groove 8 is arranged on the entire circumference, cutting of cutting conditions is not limited.

  The cutting inserts 1 and 20 of the present invention are so-called negative type cutting inserts and can be manufactured by a known method. That is, the cutting inserts 1 and 20 can be manufactured by powder pressure molding and sintering. The sintered cutting inserts 1 and 20 can be further subjected to grinding processing, polishing processing, coating film coating, and the like. The contact land portion 7a and the central surface 9 can be formed by powder pressure molding and sintering. Furthermore, when the contact land portion 7a and the central surface 9 are ground simultaneously, the contact land portion 7a can be easily arranged with high accuracy on a virtual plane where the central surface 9 is extended.

  As mentioned above, although embodiment was described as an example about the cutting insert of this invention, this invention is not limited to the above-mentioned thing. For example, the present invention is not limited to a cutting insert for a lathe, and can be applied to a cutting insert for drilling or milling.

  Although the present invention has been described with a certain degree of specificity in the above-described embodiment and its modifications, the present invention is not limited to the above-described embodiment. It should be understood that various changes and modifications can be made to the present invention without departing from the spirit and scope of the claimed invention. That is, the present invention includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims.

1 Cutting insert 2 First end face (upper surface)
3 Second end face (lower face)
4 peripheral side surface 5 cutting edge 5a first cutting edge part 5b second cutting edge part 5c third cutting edge part 5d fourth cutting edge part 6 corner part 6a first corner part 7 land 7a contact land part 8 Chip breaker groove 9 Central surface 10 Mounting hole 20 Cutting insert A Reference axis B Inscribed circle size C Minimum value of chip breaker width D Land width E Cutting edge height difference F From first cutting edge to first corner Length of the part up to the remote part

Claims (6)

A first end face (2), a second end face (3) facing the first end face (2), and a circumference connecting the first end face (2) and the second end face (3). A cutting insert (1, 20) having a side edge (4), a cutting edge (5) at an intersecting ridge line portion between the first end face (2) and the peripheral side face (4),
The first end surface (2) has at least one corner portion (6a), a central surface (9), and a concave chip breaker groove (8) surrounding the central surface (9),
The cutting edge (5) is spaced apart from the first cutting edge part (5a) at the corner part (6a) and the second end face (3) from the first cutting edge part (5a), and A second cutting edge (5b) substantially parallel to the second end face (3),
It said first end face (2) have a land (7a) along the second cutting edge portion (5b),
The second end face (2a) of the second cutting edge part (5b) and the corner part (6a) when viewed from the direction facing the peripheral side surface (4), the second cutting edge part (5b). 3) The height difference (E) from the side is 0.03 mm or more and 1 mm or less,
The length (F) from the second cutting edge (5b) to the farthest part of the corner (6a) along the extending direction of the second cutting edge (5b) is 3 mm or more. , 6 mm or less,
The first end face (2) is a substantially rhombus or a substantially hexagon whose inscribed circle dimension (B) is determined,
The length (F) from the second cutting edge (5b) to the farthest part of the corner part (6a) along the extending direction of the second cutting edge (5b) is the inscribed circle. Cutting insert that is 30% or more and 60% or less with respect to dimension (B) .   The cutting insert of Claim 1 which has a cutting edge (5) in the cross ridgeline part of a said 2nd end surface (3) and the said surrounding side surface (4). The central surface (9a) is a substantially flat surface,
The cutting insert according to claim 1 or 2, wherein a portion of the land (7a) farthest from the second end face (3) side is located on a virtual plane where the central face (9) is extended.   The said land (7a) is a cutting insert as described in any one of Claim 1 to 3 which has a substantially flat surface in the part connected with the said 2nd cutting-blade part (5b) at least.   The width (D) of the land (7a) from the second cutting edge (5b) is 0.15 mm or more and 0.5 mm or less when viewed from the direction facing the first end surface (2). The cutting insert according to any one of claims 1 to 4. A first end face (2), a second end face (3) facing the first end face (2), and a circumference connecting the first end face (2) and the second end face (3). A cutting insert (1, 20) having a side edge (4), a cutting edge (5) at an intersecting ridge line portion between the first end face (2) and the peripheral side face (4),
The first end surface (2) has at least one corner portion (6a), a central surface (9), and a concave chip breaker groove (8) surrounding the central surface (9),
The cutting edge (5) is spaced apart from the first cutting edge part (5a) at the corner part (6a) and the second end face (3) from the first cutting edge part (5a), and A second cutting edge (5b) substantially parallel to the second end face (3),
The first end face (2) has a land (7a) along the second cutting edge (5b),
The second end face (2a) of the second cutting edge part (5b) and the corner part (6a) when viewed from the direction facing the peripheral side surface (4), the second cutting edge part (5b). 3) The height difference (E) from the side is 0.03 mm or more and 1 mm or less,
The length (F) from the second cutting edge (5b) to the farthest part of the corner (6a) along the extending direction of the second cutting edge (5b) is 3 mm or more. , 6 mm or less,
The first end face (2) is a substantially triangular shape having an inscribed circle dimension (B) determined;
The length (F) from the second cutting edge (5b) to the farthest part of the corner part (6a) along the extending direction of the second cutting edge (5b) is the inscribed circle. dimensions (B) to 50% or more, der Ru cutting insert 80% or less.

Images