Cutting insert and cutting tool

Abstract

In a cutting insert 10 having an upper surface part 11 and a lower surface part 12 having a substantially pentagonal shape, and a side surface part 13 between the upper surface part and the lower surface part, a flat edge 14 is formed at each corner part in the upper surface part intersecting with the side surface part and the lower surface part, a first main cutting edge 15 and a second main cutting edge 16 are formed between the corner parts corresponding to the respective flat edges, an angle θ1 formed by the flat edge and the first main cutting edge is set to fall in a range of 15° to 30°, and an angle θ2 formed by the flat edge and the second main cutting edge is set to fall in a range of 40° to 50°.

Description

Cutting inserts and cutting tools

[0001] The present invention relates to a cutting insert and a cutting tool in which the cutting insert is removably mounted in an insert pocket of a tool body. In particular, the present invention is characterized in that when cutting a workpiece using a cutting tool in which the cutting insert is mounted in the insert pocket of the tool body, it is possible to stably perform not only high-feed cutting but also high-depth cutting with a deep axial depth of cut.

[0002] BACKGROUND ART Conventionally, a workpiece has been cut using a cutting tool having a cutting insert mounted in an insert pocket of a tool body.

[0003] Here, as the cutting insert, for example, as shown in Patent Documents 1 to 4, a cutting insert having polygonal upper and lower surface portions and side portions between the upper and lower surface portions, in which a wiper blade is formed at each corner portion of the upper surface side intersection portion where the upper surface portion and the side portion intersect and the lower surface side intersection portion where the lower surface portion and the side portion intersect, and a main cutting edge is provided between the corner portions so as to correspond to each wiper blade, is used.

[0004] In cutting tools in which the cutting insert described above is mounted in an insert pocket, in order to increase the feed rate in the surface direction and perform high-feed machining, the ridge line of the main cutting edge of the cutting insert is inclined to adjust the axial rake angle of the main cutting edge to a positive angle, or the angle of the main cutting edge relative to the scraper edge is reduced.

[0005] However, when a cutting tool is used in which the axial rake angle of the main cutting edge is adjusted to a positive angle and the angle of the main cutting edge relative to the scraper edge is reduced, and high-depth cutting with a deep axial cut is performed, problems arise such as the load on the main cutting edge becoming large and the main cutting edge being damaged.

[0006] Patent No. 5357963 Patent No. 5369185 Patent No. 5441615 Patent No. 5468172

[0007] The present invention aims to solve the above-mentioned problems that occur when cutting is performed using a cutting tool in which a cutting insert is mounted in an insert pocket of a tool body, and in which a scraper edge is formed at each corner of an upper surface intersection where a polygonal upper surface and a side surface intersect, and at a lower surface intersection where a polygonal lower surface and a side surface intersect, and in which a main cutting edge is formed to correspond to each scraper edge.

[0008] That is, the present invention aims to make it possible to stably perform high-feed cutting with a fast feed rate in the surface direction as well as high-depth cutting with a deep axial depth of cut when cutting a workpiece using the cutting tool described above.

[0009] In order to solve the above-mentioned problems, the cutting insert of the present invention has upper and lower surface portions each having a substantially pentagonal shape and side portions between the upper and lower surface portions, and a wiper edge is formed at each corner portion of the upper and lower surface portions that intersect with the side portions, and a first major cutting edge and a second major cutting edge are formed between each corner portion so as to be continuous with the wiper edge, and the angle θ1 formed between the wiper edge and the first major cutting edge is smaller than the angle θ2 formed between the wiper edge and the second major cutting edge, and the angle θ1 formed between the wiper edge and the first major cutting edge is in the range of 15° to 30°, and the angle θ2 formed between the wiper edge and the second major cutting edge is in the range of 40° to 50°.

[0010] When the workpiece is cut by the wiper edge and the first major cutting edge of the cutting insert and not by the second major cutting edge, the angle θ1 between the wiper edge and the first major cutting edge is small as described above, thereby reducing the cutting resistance to the workpiece and enabling efficient high-feed cutting. On the other hand, when the workpiece is cut by the wiper edge, the first major cutting edge, and the second major cutting edge, the angle θ2 between the wiper edge and the second major cutting edge is larger than the angle θ1 between the wiper edge and the first major cutting edge, thereby enabling efficient high-depth cutting by the second major cutting edge when performing cutting with a deep axial depth.

[0011] Furthermore, in the cutting insert of the present invention, in a cutting insert having polygonal upper and lower surface portions and side portions between the upper and lower surface portions, a wiper edge is formed at each corner portion of the upper and lower surface portions that intersect with the side portions, and a first main cutting edge and a second main cutting edge are formed between the corner portions corresponding to each wiper edge, and the angle θ1 between the wiper edge and the first main cutting edge is made smaller than the angle θ2 between the wiper edge and the second main cutting edge, and the cutting edge angle α1 between the upper surface portion and the side portion or the lower surface portion and the side portion that constitute the first main cutting edge is an acute angle, and the cutting edge angle α2 between the upper surface portion and the side portion or the lower surface portion and the side portion that constitute the second main cutting edge is made an obtuse angle.

[0012] In this way, when the cutting edge angle α1 between the upper surface and the side surface or the lower surface and the side surface of the first major cutting edge is made acute, the cutting resistance when the wiper edge and the first major cutting edge cut the workpiece is reduced, and high-feed cutting can be performed more efficiently. On the other hand, when the cutting edge angle α2 between the upper surface and the side surface or the lower surface and the side surface of the second major cutting edge is made obtuse, the strength of the second major cutting edge is increased, and when cutting with a deep axial depth of cut, the second major cutting edge is not damaged, and stable high-depth cutting can be performed.

[0013] Furthermore, the cutting insert of the present invention may have a substantially pentagonal planar shape.

[0014] In addition, in the cutting insert of the present invention, the angle θ1 between the wiper edge and the first major cutting edge can be set in the range of 15° to 30°, and the angle θ2 between the wiper edge and the second major cutting edge can be set in the range of 40° to 50°.

[0015] In this way, when the angle θ1 between the wiper edge and the first major cutting edge is in the range of 15° to 30°, the cutting resistance to the workpiece is reduced, and high-feed cutting can be performed more efficiently. On the other hand, when the angle θ2 between the wiper edge and the second major cutting edge is in the range of 40° to 50°, high-depth cutting with a deep axial depth of cut can be performed more efficiently by the second major cutting edge.

[0016] In the cutting tool of the present invention, the cutting insert is attached to the insert pocket of the tool body.

[0017] In the cutting tool of the present invention, when the workpiece is cut by the wiper edge and the first major cutting edge of the cutting insert as described above and the second major cutting edge is not used, the angle θ1 between the wiper edge and the first major cutting edge is small, thereby reducing the cutting resistance to the workpiece and enabling efficient high-feed cutting. On the other hand, when the workpiece is cut by the wiper edge, the first major cutting edge, and the second major cutting edge of the cutting insert as described above, the angle θ2 between the wiper edge and the second major cutting edge is larger than the angle θ1 between the wiper edge and the first major cutting edge, thereby enabling efficient high-depth cutting with a deep axial depth of cut by the second major cutting edge.

[0018] Furthermore, in the cutting tool of the present invention, when the cutting insert is mounted in the insert pocket of the tool body, a first restraint portion is provided that abuts against at least one of the side portions of the first main cutting edge portion and the second main cutting edge portion on one side of one corner portion of the cutting insert, and a second restraint portion is provided that abuts against at least one of the side portions of the first main cutting edge portion and the second main cutting edge portion on the opposite side of the corner portion, so that the cutting insert can be restrained in the insert pocket by the first restraint portion and the second restraint portion.

[0019] Here, when the cutting insert is constrained within the insert pocket by the first constraining portion and the second constraining portion as described above, if the first constraining portion and the second constraining portion are both directed from the corner portion toward the tip side of the tool body, the cutting insert is constrained by the first constraining portion and the second constraining portion so that it faces toward the tip side of the tool body, and the cutting insert is prevented from rattling within the insert pocket and shifting out of position during cutting processing.

[0020] Furthermore, in the cutting tool of the present invention, when a cutting insert having an acute cutting edge angle α1 between the upper surface and the side surface or the lower surface and the side surface that constitute the first main cutting edge and an obtuse cutting edge angle α2 between the upper surface and the side surface or the lower surface and the side surface that constitute the second main cutting edge is attached to an insert pocket provided in the tool body, a first constraint portion abutting the side surface of the second main cutting edge portion on one side of one corner portion of the cutting insert, and a second constraint portion abutting the side surface of the second main cutting edge portion on the opposite side can be provided, and the cutting insert can be constrained within the insert pocket by the first constraint portion and the second constraint portion.

[0021] When the cutting insert is constrained within the insert pocket by the first constraining portion and the second constraining portion as described above, the side portions of the second main cutting edge portion, where the cutting edge angle α2 is obtuse on both sides of the corner portion of the cutting insert, abut against the first constraining portion and the second constraining portion, respectively, and each side portion of the second main cutting edge portion on both sides of the corner portion of the cutting insert is constrained by being pressed into the insert pocket by the first constraining portion and the second constraining portion, thereby reliably preventing the cutting insert from rattling within the insert pocket and shifting out of position during cutting processing.

[0022] In the present invention, the cutting insert to be mounted in the insert pocket of the tool body as described above has polygonal upper and lower surface portions and side portions between the upper and lower surface portions, and has scraping edges formed at each corner portion of the upper and lower surface portions that intersect with the side portions, and has first and second main cutting edges formed between the corner portions corresponding to each scraping edge, and the angle θ1 between the scraping edge and the first main cutting edge is smaller than the angle θ2 between the scraping edge and the second main cutting edge.

[0023] When a cutting tool having the cutting insert mounted in the insert pocket of the tool body is used to cut a workpiece using the wiper blade and first main cutting edge of the cutting insert, and cutting is not performed using the second main cutting edge, the angle θ1 between the wiper blade and first main cutting edge is small, thereby reducing the cutting resistance to the workpiece and enabling efficient high-feed cutting; and when a workpiece is cut using the wiper blade, first main cutting edge, and second main cutting edge of the cutting insert, the angle θ2 between the wiper blade and second main cutting edge is larger than the angle θ1 between the wiper blade and first main cutting edge, thereby enabling efficient high-depth cutting with a deep axial depth of cut by the second main cutting edge.

[0024] 1 is a schematic perspective view showing a cutting insert in a first embodiment of the present invention. FIG. 2 is a schematic plan view showing the cutting insert in the first embodiment. FIG. 3 is a schematic side view showing the cutting insert in the first embodiment. FIG. 4 is a schematic explanatory view showing a cutting tool in which the cutting insert is attached in an insert pocket of a tool body in the first embodiment. FIG. 5 is a partial schematic explanatory view showing a state in which the cutting insert is constrained in the insert pocket of the tool body by a first constraining portion and a second constraining portion provided in the insert pocket. FIG. 6 is a partial schematic explanatory view showing a state in which a workpiece is cut by a wiper edge and a first major cutting edge provided in the cutting insert in the cutting tool in the first embodiment. FIG. 7 is a partial schematic explanatory view showing a state in which a workpiece is cut by a wiper edge, a first major cutting edge, and a second major cutting edge provided in the cutting insert in the cutting tool in the first embodiment. 1A is a partial cross-sectional view of a first major cutting edge having an acute cutting edge angle α1, and FIG. 1B is a partial cross-sectional view of a second major cutting edge having an obtuse cutting edge angle α2, in a cutting insert according to the second embodiment. FIG. 1B is a schematic explanatory view showing a cutting tool in which the cutting insert is attached to an insert pocket of a tool body according to the second embodiment. FIG. 1C is a partial schematic explanatory view showing a state in which the cutting insert is constrained in the insert pocket of the tool body by first and second constraining portions provided in the insert pocket. FIG. 1D is a partial schematic explanatory view showing a state in which a workpiece is cut by a wiper edge and a first major cutting edge provided in the cutting insert according to the second embodiment. FIG. 1E is a partial schematic explanatory view showing a state in which a workpiece is cut by a wiper edge, a first major cutting edge, and a second major cutting edge provided in the cutting insert according to the second embodiment.

[0025] Hereinafter, cutting inserts and cutting tools according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. The cutting inserts and cutting tools according to the present invention are not limited to the following embodiments, and can be modified as appropriate within the scope of the present invention.

[0026] (Embodiment 1) As shown in Figures 1 to 3, the cutting insert 10 used in embodiment 1 has an upper surface portion 11 and a lower surface portion 12 that are substantially pentagonal in shape, and a side surface portion 13 between the upper surface portion 11 and the lower surface portion 12. A scraper edge 14 is formed at each corner portion of the upper surface portion 11 and the lower surface portion 12 that intersects with the side surface portion 13, and a first main cutting edge 15 and a second main cutting edge 16 are formed between the corner portions corresponding to the scraper edges 14. A mounting hole 17 is provided so as to penetrate through the center of the upper surface portion 11 and the lower surface portion 12.

[0027] Here, in the cutting insert 10, the upper surface portion 11 and the lower surface portion 12 are inverted, and a second major cutting edge 16 is formed at the intersection of the lower surface portion 12 and the side surface portion 13 corresponding to the portion of the first major cutting edge 15 where the upper surface portion 11 and the side surface portion 13 intersect, and the first major cutting edge 15 is formed at the intersection of the lower surface portion 12 and the side surface portion 13 corresponding to the portion of the second major cutting edge 16 where the upper surface portion 11 and the side surface portion 13 intersect. Although not shown, the cutting edge angle of the first major cutting edge 15 and the cutting edge angle of the second major cutting edge 16 are set to be the same angle.

[0028] In addition, in the cutting insert 10, as shown in FIG. 2, the angle θ1 formed between the wiper edge 14 and the first major cutting edge 15 is set in the range of 15° to 30°, while the angle θ2 formed between the wiper edge 14 and the second major cutting edge 16 is set in the range of 40° to 50°, and the angle θ1 formed between the wiper edge 14 and the first major cutting edge 15 is smaller than the angle θ2 formed between the wiper edge 14 and the second major cutting edge 16.

[0029] In the first embodiment, as shown in FIG. 4, the cutting insert 10 is attached to each insert pocket 21 provided in the tool body 20 by means of attachment screws 22 through attachment holes 17 provided in the cutting insert 10.

[0030] Here, when the cutting insert 10 is attached to the insert pocket 21 provided in the tool body 20 by the attachment screw 22, as shown in FIG. 5 , a first constraint portion 23 a is provided in the insert pocket 21 on both sides of the corner portion where the wiper edge 14 that performs cutting is formed, located in the insert pocket 51 away from the corner portion where the wiper edge 14 that performs cutting is formed, so as to abut against the side portion 13 (13 a) of the first major cutting edge 15 (15 a) located on the outer periphery side of the tool body 20 relative to the corner portion, and a second constraint portion 23 b is provided in the insert pocket 21 so as to abut against the side portion 13 (13 b) of the second major cutting edge 16 (16 b) located on the inner periphery side of the tool body 20 relative to the corner portion, and the second constraint portion 23 b is provided to the first constraint portion 23 a, and the cutting insert 10 is constrained in the insert pocket 21 by the first constraint portion 23 a and the second constraint portion 23 b.

[0031] In the above-mentioned embodiment 1, the first restraint portion 23a and the second restraint portion 23b on both sides of the corner portion where the scraper edge 14 located in the insert pocket 51 is formed are inclined from the corner portion toward the tip side of the tool body 20, so that the cutting insert 10 is restrained toward the tip side of the tool body 1, and the cutting insert 10 is prevented from rattling and shifting position within the insert pocket 21 of the tool body 20 during cutting processing.

[0032] In this embodiment 1, as described above, the first restraint portion 23a of the insert pocket 21 restrains the side portion 13 (13a) of the first main cutting edge 15 (15a) located closer to the outer periphery of the tool body 20 than the corner portion, and the second restraint portion 23b restrains the side portion 13 (13b) of the second main cutting edge 16 (16b) located closer to the inner periphery of the tool body 20 than the corner portion, but the side portion 13 that is restrained by the first restraint portion 23a and the second restraint portion 23b is not limited to this. For example, although not shown, it is also possible to have the first restraint portion 23a restrain the side portion 13 of the second main cutting edge 16 in addition to the side portion 13 (13a) of the first main cutting edge 15 (15a) located closer to the outer periphery of the tool body 20 than the corner portion, or to have the second restraint portion 23b restrain the side portion 13 of the first main cutting edge 15 in addition to the side portion 13 (13b) of the second main cutting edge 16 (16b) located closer to the inner periphery of the tool body 20 than the corner portion.

[0033] In the cutting tool of the first embodiment, as shown in Figure 6, when the workpiece W is cut by the scraper edge 14 and the first main cutting edge 15 at the corner portion of the cutting insert 10 protruding from the insert pocket 21 of the tool body 20 and cutting is not performed by the second main cutting edge 16, the angle θ1 between the scraper edge 14 and the first main cutting edge 15 that cut the workpiece W is small, so that the cutting resistance to the workpiece W is reduced and high-feed cutting can be performed efficiently.

[0034] On the other hand, in the cutting tool of the first embodiment, as shown in FIG. 7, when the workpiece W is cut by the scraper edge 14, the first main cutting edge 15, and the second main cutting edge 16 at the corner portion of the cutting insert 10 protruding from the insert pocket 21 of the tool body 20, the angle θ2 formed by the scraper edge 14 and the second main cutting edge 16 is larger than the angle θ1 formed by the scraper edge 14 and the first main cutting edge 15, and therefore, high-depth cutting can be performed efficiently by the second main cutting edge 16.

[0035] (Embodiment 2) As shown in Figures 8 to 10, the cutting insert 10 used in embodiment 2 has an upper surface portion 11 and a lower surface portion 12 each having a substantially pentagonal shape, and a side surface portion 13 between the upper surface portion 11 and the lower surface portion 12, similar to the cutting insert 10 used in embodiment 1. Wiper edges 14 are formed at each corner portion of the upper surface portion 11 and the lower surface portion 12 that intersect with the side surface portion 13, and first and second main cutting edges 15 and 16 are formed between the corner portions corresponding to the wipers 14. A mounting hole 17 is provided so as to penetrate through the center of the upper surface portion 11 and the lower surface portion 12.

[0036] Here, in the cutting insert 10, the upper surface portion 11 and the lower surface portion 12 are in an inverted state, and a second main cutting edge 16 is formed at the portion where the lower surface portion 12 and the side surface portion 13 intersect, which corresponds to the portion of the first main cutting edge 15 where the upper surface portion 11 and the side surface portion 13 intersect, and a first main cutting edge 15 is formed at the portion where the lower surface portion 12 and the side surface portion 13 intersect, which corresponds to the portion of the second main cutting edge 16 where the upper surface portion 11 and the side surface portion 13 intersect.

[0037] In addition, in the cutting insert 10, as shown in FIG. 2, the angle θ1 formed between the wiper edge 14 and the first major cutting edge 15 is set in the range of 15° to 30°, while the angle θ2 formed between the wiper edge 14 and the second major cutting edge 16 is set in the range of 40° to 50°, and the angle θ1 formed between the wiper edge 14 and the first major cutting edge 15 is smaller than the angle θ2 formed between the wiper edge 14 and the second major cutting edge 16.

[0038] On the other hand, in the cutting insert 10 used in embodiment 2, as shown in Figures 11 (A) and (B), the cutting edge angle α1 of the first major cutting edge 15 is an acute angle, while the cutting edge angle α2 of the second major cutting edge 16 is an obtuse angle.

[0039] In the second embodiment, as shown in FIG. 12, the cutting insert 10 is attached to each insert pocket 21 provided in the tool body 20 by means of attachment screws 22 through attachment holes 17 provided in the cutting insert 10.

[0040] Here, when the cutting insert 10 is attached in the insert pocket 21 provided in the tool body 20 by the attachment screw 22, as shown in Figure 13, the cutting insert 10 is set in the insert pocket 21 and attached so that the side portion 13 of the second main cutting edge 16, which has an obtuse cutting edge angle α2 provided continuously with the scraper edge 14 and the first main cutting edge 15 at the cutting position, does not protrude outward, so that the side portion 13 of the second main cutting edge 16 comes into contact with the workpiece W when cutting the workpiece W, and damages the workpiece W and the cutting insert 10 are prevented.

[0041] Furthermore, when the cutting insert 10 is attached by the attachment screw 22 into the insert pocket 21 provided in the tool body 20, in order to prevent the cutting insert 10 from rattling and shifting position inside the insert pocket 21 of the tool body 20 during cutting, first constraint portions 23a are provided in the insert pocket 21 so as to abut against the side portion 13 (13a) of the second main cutting edge 16 (16a) located on the outer periphery of the tool body 20 relative to the corner portion on both sides of the corner portion where the scraper edge 14 that performs cutting is formed, which is located in the insert pocket 51 away from the corner portion where the scraper edge 14 that performs cutting is formed, and second constraint portions 23b are provided in the insert pocket 21 so as to abut against the side portion 13 (13b) of the second main cutting edge 16 (16b) located on the inner periphery of the tool body 20 relative to the corner portion, and the cutting insert 10 is constrained in the insert pocket 21 by the first constraint portions 23a and the second constraint portions 23b.

[0042] Here, when the cutting insert 10 is constrained within the insert pocket 21 in the manner described above, the side portions 13 (13a), 13 (13b) of the second main cutting edges 16 (16a), 16 (16b) on both sides of the corner portion within the insert pocket 51, where the cutting edge angle α2 is an obtuse angle, are abutted against the first constraining portion 23a and the second constraining portion 23b, respectively, and the side portions 13 (13a), 13 (13b) of the second main cutting edges 16 (16a), 16 (16b) on both sides of the corner portion are constrained by being pressed into the insert pocket 21 by the first constraining portion 23a and the second constraining portion 23b, thereby reliably preventing the cutting insert 10 from rattling within the insert pocket 21 and becoming misaligned during cutting.

[0043] 14 , in the cutting tool of the second embodiment, when the workpiece W is cut by the wiper edge 14 and the first major cutting edge 15 at the corner portion of the cutting insert 10 protruding from the insert pocket 21 of the tool body 20, and cutting is not performed by the second major cutting edge 16, the angle θ1 between the wiper edge 14 and the first major cutting edge 15 that cut the workpiece W is small, and the cutting edge angle α1 of the first major cutting edge 15 is acute, so that the cutting resistance to the workpiece W is reduced and high-feed cutting can be performed efficiently.

[0044] On the other hand, in the cutting tool of the first embodiment, as shown in FIG. 15 , when the workpiece W is cut by the scraper edge 14, the first major cutting edge 15, and the second major cutting edge 16 at the corner portion of the cutting insert 10 protruding from the insert pocket 21 of the tool body 20, the angle θ2 formed by the scraper edge 14 and the second major cutting edge 16 is larger than the angle θ1 formed by the scraper edge 14 and the first major cutting edge 15, so that the second major cutting edge 16 can efficiently perform high-depth cutting, and further, since the cutting edge angle α2 of the second major cutting edge 16 is an obtuse angle, the cutting edge strength of the second major cutting edge 16 is increased, and damage to the second major cutting edge 16 is prevented.

[0045] 1: Tool body 10: Cutting insert 11: Upper surface portion 12: Lower surface portion 13: Side portion 14: Wiper edge 15: First main cutting edge 16: Second main cutting edge 17: Mounting hole 20: Tool body 21: Insert pocket 22: Mounting screw 23a: First constraint portion 23b: Second constraint portion 51: Insert pocket W: Workpiece α1: Cutting edge angle of first main cutting edge α2: Cutting edge angle of second main cutting edge θ1: Angle between wiper edge and first main cutting edge θ2: Angle between wiper edge and second main cutting edge

Claims

1. A cutting insert having upper and lower surfaces that are approximately pentagonal and side surfaces between the upper and lower surfaces, wherein a scraper edge is formed at each corner of the upper and lower surfaces that intersect with the side surfaces, and a first main cutting edge and a second main cutting edge are formed between the corners so as to be continuous with the scraper edge, and the angle θ1 between the scraper edge and the first main cutting edge is smaller than the angle θ2 between the scraper edge and the second main cutting edge, and the angle θ1 between the scraper edge and the first main cutting edge is in the range of 15° to 30°, and the angle θ2 between the scraper edge and the second main cutting edge is in the range of 40° to 50°.

2. A cutting insert having polygonal upper and lower surface portions and side portions between the upper and lower surface portions, wherein a scraper edge is formed at each corner portion of the upper and lower surface portions that intersect with the side portions, and a first main cutting edge and a second main cutting edge are formed between the corner portions corresponding to each scraper edge, and the angle θ1 between the scraper edge and the first main cutting edge is smaller than the angle θ2 between the scraper edge and the second main cutting edge, and the cutting edge angle α1 between the upper surface portion and the side portion or the lower surface portion and the side portion that constitute the first main cutting edge is an acute angle, and the cutting edge angle α2 between the upper surface portion and the side portion or the lower surface portion and the side portion that constitute the second main cutting edge is an obtuse angle.

3. The cutting insert according to claim 2, characterized in that the cutting insert has a substantially pentagonal shape.

4. A cutting insert as claimed in claim 2, characterized in that the angle θ1 between the wiper edge and the first major cutting edge is in the range of 15° to 30°, and the angle θ2 between the wiper edge and the second major cutting edge is in the range of 40° to 50°.

5. A cutting tool characterized in that the cutting insert according to claim 1 or 2 is attached in an insert pocket provided in the tool body.

6. A cutting tool as described in claim 5, characterized in that when the cutting insert is attached to the insert pocket of the tool body, a first restraining portion is provided that abuts against at least one of the side surfaces of the first main cutting edge portion and the second main cutting edge portion on one side of one corner portion of the cutting insert, and a second restraining portion is provided that abuts against at least one of the side surfaces of the first main cutting edge portion and the second main cutting edge portion on the opposite side of the corner portion, and the cutting insert is restrained in the insert pocket by the first restraining portion and the second restraining portion.

7. A cutting tool having an insert pocket provided in the tool body and the cutting insert described in claim 2 attached thereto, characterized in that a first restraint portion is provided that abuts against the side portion of the second main cutting edge portion on one side of one corner portion of the cutting insert, and a second restraint portion is provided that abuts against the side portion of the second main cutting edge portion on the opposite side, and the cutting insert is restrained within the insert pocket by the first restraint portion and the second restraint portion.

Images