JP6124040B2 - Body and cutting edge exchangeable cutting tools for cutting tools - Google Patents

Description

  The present invention relates to a body for a cutting tool and a cutting edge exchangeable cutting tool in which a cutting insert is detachably attached to the body.

  As shown in Patent Document 1, conventionally, there is a blade type exchangeable cutting tool of a type in which a cutting insert including a cutting edge is detachably attached to an insert mounting seat formed at the tip of a body. In the case of such a blade-tip-exchangeable cutting tool, when the cutting blade of the cutting insert is worn or chipped, the damaged cutting insert is replaced, or if the cutting insert has a plurality of cutting blades, it is rotated. It is very economical because it is sufficient to let it be reattached.

  Here, as one method for firmly attaching the cutting insert to the insert mounting seat, the lower surface of the cutting insert is fixed to the insert mounting seat by screwing the screw head into contact with the upper surface portion of the cutting insert. There is a method in which a force for pressing the cutting insert toward the side wall of at least two insert mounting seats is applied simultaneously with the force for pressing the bottom surface. However, using this method, the cutting insert can rotate in the insert seat due to the friction between the screw and the cutting insert that occurs when the screw is tightened. Therefore, it is practically difficult to manufacture the insert mounting seat and the cutting insert with high accuracy so that the two side wall portions of the insert mounting seat and the two side surface portions of the corresponding cutting insert are brought into surface contact with each other. Usually, only one set is in surface contact and the other set of side wall portions is in contact with the side portion of the cutting insert only at its end. In addition, there is a limit to manufacturing the two sets with high precision so as to cause surface contact. Eventually, due to various variations, the contact point of the other side wall portion is the two end portions of the side wall portion. Can be on either side. Therefore, the contact state of the cutting insert is not stable. If the contact location changes, the fixed state with respect to the insert mounting seat and the direction of the cutting insert with respect to the work material also changes, and therefore the quality of the cutting process is not stable even if the cutting is performed under the same cutting conditions.

  Therefore, Patent Document 1 discloses a blade-exchange-type cutting tool with a limited contact location. Specifically, a recess is provided on each of two adjacent side surfaces of the cutting insert, and the cutting insert is statically configured by contacting the side edge of the recess with the adjacent side wall on the insert mounting seat side at three points. Is going to be retained.

JP-T-2004-520181

  However, the blade-tip-exchangeable cutting tool of Patent Document 1 has a contact point at a certain small region that is a side edge of a recess provided on the side surface of a cutting insert, that is, a thin portion that is likely to be damaged due to stress concentration. Therefore, the strength of the cutting insert is never sufficient, and the mounting stability may be impaired.

  SUMMARY OF THE INVENTION In view of the above problems, the present invention has an object to provide a body and a blade-tip-exchangeable cutting tool that can be stably attached to substantially the same place with respect to the cutting insert and the insert mounting seat while maintaining the strength of the cutting insert. To do.

The body of the cutting edge replaceable cutting tool of the present invention includes an insert mounting seat for mounting a cutting insert having a substantially polygonal end surface, and the insert mounting seat includes a bottom surface and a side wall, 1st and 2nd side wall which contact | abuts the side part of two side surfaces of the side surfaces of the said cutting insert connected to an end surface, respectively, Comprising: It is located in the front end side and proximal end side of the said body, respectively The first side wall has a concave curved side wall portion that is curved so as to be recessed, and contacts the side surface portion of the cutting insert only at the concave curved side wall portion.

  In the above, the body has a substantially cylindrical shape, and the side wall forms a mounting space for the cutting insert having openings opened on the distal end side and the outer peripheral side of the cylindrical body, and the concave curve The side wall portion is preferably provided at a position biased toward the outer peripheral side. Here, the concave curved side wall portion may be formed so that one end thereof faces the opening.

  In the present specification and claims, the “side wall portion” means a part of the side wall that can be cut off by two imaginary planes extending perpendicularly to the wall surface of the side wall and parallel to the height direction of the side wall. In other words, the term “side wall part” does not refer to any part of the side wall, but refers to a part of the side wall that is erected on the bottom surface and is defined as a “wall”. Used as

  The cutting edge-exchange-type cutting tool of this invention is equipped with the said body and the cutting insert which has a convex side part contact | abutted to the said concave curved side wall part of the said insert mounting seat.

  In this cutting edge replaceable cutting tool, when viewed from the direction facing the bottom surface of the insert mounting seat, the concave curved side wall portion is substantially arc-shaped, and when viewed from the direction facing the end surface of the cutting insert, the convex shape It is preferable that the side surface portion has a substantially arc shape and the curvature radius of the convex side surface portion is equal to or less than the curvature radius of the concave curved side wall portion.

  In the present specification and claims, the “side surface” is a part of the side surface connecting the opposing end surfaces of the cutting insert. If the end surface is substantially polygonal, it is a portion including one corresponding side ridge portion of the two end surfaces, and the cutting insert includes a plurality of side surfaces. For example, if the basic shape of the end face is a triangular cutting insert, it has three side faces, and if the basic shape is a square cutting insert, it has four side faces. Side. Further, the “side surface portion” does not refer to an arbitrary portion of the side surface, but refers to a portion of the side surface that is defined as being capable of actually contacting the “side wall portion” of the body.

  Moreover, when the cutting edge replaceable cutting tool of the present invention is viewed from above the cutting insert, the cutting insert includes three corners and three side ridges connecting the corners, and when the cutting insert is viewed from the side, The side ridge portion includes a concave curved side ridge portion that curves toward the lower surface, and the portion of the concave curved side ridge portion that is closest to the lower surface is the length of the side ridge portion from the center of the side ridge portion to the left and right. It is preferable to be within an area that is limited to a position 10% away.

  Furthermore, it is preferable that the cutting edge exchange type cutting tool of the present invention has a shape that is 180 ° rotationally symmetric with respect to a rotation axis that penetrates the side surface of the cutting insert.

  According to the body and the blade-tip-exchangeable cutting tool of the present invention, the contact location between the cutting insert and the side wall of the insert mounting seat can be stabilized at a predetermined position every time. Therefore, the mounting state of the cutting insert is constant, and the quality of the cutting process is stable. Since no recess is formed on the side surface of the cutting insert, the strength is higher than that of the conventional cutting insert disclosed in Patent Document 1.

FIG. 1 is a view of a cutting edge-replaceable cutting tool according to an embodiment of the present invention as seen from a direction facing a bottom surface of one insert mounting seat. FIG. 2 is a perspective view of a body according to an embodiment of the present invention. FIG. 3 is a view of the body of FIG. 2 as viewed from the direction facing the bottom surface of one insert mounting seat. 4 is an enlarged perspective view of the insert mounting seat of FIG. FIG. 5 is an enlarged view of the body of FIG. 2 as viewed from the direction facing the bottom surface of one insert mounting seat. FIG. 6 is a perspective view of a blade-tip-exchangeable cutting tool according to an embodiment of the present invention. FIG. 7 is an enlarged view of the cutting edge replaceable cutting tool of FIG. 1 as viewed from the direction facing the bottom surface of the insert mounting seat. FIG. 8 is a view of the blade-tip-exchangeable cutting tool of FIG. 1 as viewed from the direction facing the side surface of the cutting insert.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following, words indicating the relative positional relationship between two objects, such as “upper”, “lower”, “right”, “left”, etc. may be used, but these are for convenience of explanation. It does not specify the absolute positional relationship between the two objects in space.

  As shown in FIG. 1, the body 10 of the present embodiment is a body of a cutting edge-exchangeable cutting tool 100 for shoulder cutting. Hereinafter, the cutting edge exchange type cutting tool 100 is simply referred to as a cutting tool 100. As shown in FIGS. 1 to 3, the body 10 has a generally cylindrical shape, and three insert attachments for attaching three plate-like cutting inserts 20 each having a substantially equilateral triangular end surface to the tip thereof. A seat 11 is provided. The insert mounting seat 11 includes a bottom surface 12 that is a contact surface with the end surface of the cutting insert 20, and side walls formed around the bottom surface 12. The bottom surface 12 is a surface having a shape corresponding to the end surface of the cutting insert 20 (that is, a substantially equilateral triangular shape). The side wall does not completely surround the bottom surface 12, but is provided so that a mounting space for the cutting insert 20 having an opening opened toward the outer circumferential direction and the front end of the body 10 is formed. A part of the cutting insert 20 protrudes from the opening, and the cutting edge in the protruding part is involved in the cutting. The side wall includes a first side wall 13 and a second side wall 14 that face in different directions. The first side wall 13 is positioned relatively on the tool distal end side, and the second side wall 14 is positioned relatively on the tool base end side. In this embodiment, the 1st side wall 13 and the 2nd side wall 14 respond | correspond to the side surface respectively connected with two sides of three sides of the substantially triangular end surface of the cutting insert 20 to be attached.

  As shown in FIG. 3, the first side wall 13 is formed so as to be inclined toward the front end side of the cutting tool 100 as it goes toward the outer peripheral side of the body 10 when viewed from the direction facing one bottom surface 12. Similarly, the second side wall 14 is formed so as to be inclined toward the base end side of the cutting tool 100 as it goes toward the outer peripheral side of the cutting tool 100. The first side wall 13 and the second side wall 14 correspond to the two sides of the substantially triangular cutting insert 20. That is, the cutting insert 20 is mounted on the insert mounting seat 11 with the side surfaces respectively connected to the two sides thereof in contact with the first side wall 13 and the second side wall 14 and one end surface in contact with the bottom surface 12. As shown in FIG. 4, when the cutting insert 20 is attached to the connecting portion between the first side wall 13 and the bottom surface 12 and the connecting portion between the second side wall 14 and the bottom surface 12, the end surface is in contact with the bottom surface 12. A gap for preventing the side ridges from coming into contact with the side surface, that is, a so-called dull 15 is formed.

  The cutting insert 20 is provided with a hole penetrating the center of the two opposite end faces. This through hole is used for inserting the screw 30 when the cutting insert 20 is mounted on the insert mounting seat 11. Both ends of the through holes that open to the opposing end faces are larger in diameter than the center. The diameter enlarged portion of the through hole has a shape and a size corresponding to the head of the screw 30, and the head of the screw 30 is in contact with a step portion formed by the diameter enlarged portion of the through hole. The On the other hand, a screw hole 16 is formed in the center of the bottom surface 12 of the insert mounting seat 11. When the cutting insert 20 is fixed, the screw 30 is screwed into the screw hole 16. The center axis of the screw hole 16 is formed at a position slightly closer to the first side wall 13 and the second side wall 14 than the center axis O of the through hole when the cutting insert 20 is placed on the insert mounting seat 11. In addition, it is formed to be slightly inclined so as to go toward the base end side and the central axis side of the body 10 as it goes deeper. As a result, the cutting insert 20 is pressed against the bottom surface 12 by the contact between the head portion of the screw 30 and the stepped portion, and at the same time, is pressed toward the first side wall 13 and the second side wall 14.

  When viewed from the direction facing one bottom surface 12, the first side wall 13 is not formed by a single flat surface, but in the direction of arrow A in FIG. For example, a concave curved side wall portion 13a that is curved so as to be recessed in an arc shape toward a direction in which a perpendicular drawn on one side located on the tip side of the body 10 extends from the center thereof is provided. Of the first side wall 13, the concave curved side wall part 13a and the part located on the center axis side of the body 10 are flat surfaces 13b. The concave curved side wall portion 13 a is formed at one end of the first side wall 13. In other words, as can be seen from FIG. 5, the concave curved side wall portion 13a is formed such that the left end thereof is connected to the flat surface 13b of the first side wall 13 and the right end thereof faces the opening. Is done.

  The second side wall 14 is directed in the direction of arrow B in FIG. 5, that is, in the direction of extending a perpendicular drawn from the center to one side located on the base end side of the body 10. And a curved receding surface 14c that is curved so as to be recessed in an arc shape, and two flat portions 14a and 14b that are formed on both sides of the curved receding surface 14c. While the two plane portions (14a, 14b) form the same plane, the curved receding surface 14c is generally recessed closer to the base end side of the body 10 than the plane, so that when the cutting insert 20 is placed These two flat portions 14 a and 14 b are in contact with the side surface of the cutting insert 20.

  Next, the cutting tool 100 using the body 10 of the above embodiment will be described. As shown in FIGS. 6 to 8, each insert mounting seat 11 formed on the body 10 has a plate-like shape having two substantially equilateral triangular end faces 23 and 24 and a side face 26 connecting them. A cutting insert 20 is mounted. Hereinafter, of the two end faces 23 and 24 of the cutting insert 20, the end face where the cutting edge is involved in cutting may be referred to as the upper face, and the other end face contacting the bottom face 12 of the insert mounting seat 11 may be referred to as the lower face. That is, in FIG. 6 and FIG. 8, the end surface indicated by reference numeral 23 is the upper surface, and the end surface indicated by reference numeral 24 is the lower surface. Each of the end faces 23 and 24 of the cutting insert 20 includes three corners 21 and three side ridges 22 that connect the corners 21 to each other. Further, both end faces 23 and 24 have a 120 ° rotationally symmetric shape around the central axis O of the through hole 25 penetrating both of the end faces 23 and 24. Therefore, when the cutting insert 20 is viewed from above, the shape is approximately a regular triangle as shown in FIG.

  The side face 26 is not given a clearance angle. That is, the cutting insert 20 is a so-called negative type cutting insert. On the upper surface 23 side, the cutting edge is formed at the intersecting ridge line between the upper surface 23 and the side surface 26. The cutting edge is formed from the corner 21 to the side edge 22. On the lower surface 24 side as well, the cutting edge is similarly formed at the intersection ridgeline of the lower surface 24 and the side surface 26. Furthermore, the shape of the cutting edge formed on the upper surface 23 side and the shape of the cutting edge formed on the lower surface 24 side are the same. Due to the shape as described above, the cutting insert 20 has a 180 ° rotationally symmetric shape around an axis that penetrates the side surface 26, that is, an axis that is orthogonal to the central axis O of the through hole 25. Accordingly, in FIG. 6, the cutting insert 20 is attached to form the lower surface in a state where the end surface indicated by reference numeral 24 is in contact with the bottom surface 12 of the insert mounting seat 11. It is also possible to contact the bottom surface 12 of the mounting seat 11.

  As described above, the cutting insert 20 of the present embodiment can be used three times by rotating 120 ° around the central axis O of the through hole 25 with respect to one end surface, and can be used six times in total on both end surfaces. Cutting insert. However, the present invention is not limited to such a configuration, and does not exclude the application of a cutting insert in which cutting edges are formed on some side ridges or a cutting insert in which cutting edges are formed only on one end face. Absent.

  As shown in FIG. 7, when the cutting insert 20 is viewed from the upper surface side, the side ridges 22 of the cutting insert 20 are positioned on the sides 27 ′ of the curved portion 27 ′ and the curved portions. And straight portions 28a 'and 28b' connected to the corners. Accordingly, the portion of the side surface 26 including the curved portion 27 ′ of the side ridge portion is similarly curved, and the portion of the side surface 26 including the straight portions 28 a ′ and 28 b ′ of the side ridge portion is flat. It becomes surface part 28a, 28b. The curved portion 27 becomes a side surface portion that can abut on the concave curved side wall portion 13 a of the first side wall 13, and the flat surface portions 28 a and 28 b become side surface portions that can abut on the two flat surface portions 14 a and 14 b of the second side wall 14. When viewed from the upper surface side, the radius of curvature of the curved portion 27 is smaller than the radius of curvature of the concave curved side wall portion 13 a when viewed from the direction facing the bottom surface 12 of the insert mounting seat 11.

  As shown in FIG. 8, when the cutting insert 20 is viewed from the side, the side ridge portion 22 is a concave curved side ridge portion that is curved toward the lower surface 24 as a whole. The lowest point at which the side ridge 22 is closest to the lower surface 24 is located at the approximate center of the side ridge 22. In addition, it is preferable that the position of the lowest point of the side ridge part 22 falls within an area limited to a position about 10% of the length of the side ridge part 22 left and right from the center of the side ridge part 22. When the position of the lowest point is in this region, the chips smoothly flow toward the proximal end side of the cutting tool 100 and are discharged.

  When the cutting insert 20 is placed on the insert mounting seat 11, the first side wall 13 of the insert mounting seat 11 is formed so as to contact the curved portion 27 of the cutting insert 20 only at the concave curved side wall portion 13a. Specifically, as shown in FIG. 7, the depth of the dent of the concave curved side wall portion 13 a is determined such that contact with the curved portion 27 occurs. On the other hand, the flat surfaces 13b of the insert mounting seats 11 are separated from each other toward the central axis side of the body 10 in this embodiment so that surface contact with the flat surface portion 28a of the cutting insert 20 does not occur. Is formed. However, the point is that the first side wall 13 only needs to be in contact with the curved portion 27 only at the concave curved side wall portion 13a, and the relationship between the flat surface 13b and the flat surface portion 28a is not limited thereto.

  On the other hand, the second side wall 14 of the insert mounting seat 11 is formed such that the two flat surface portions 14 a and 14 b are side wall portions that contact the flat surface portions 28 a and 28 b of the cutting insert 20. That is, the curved receding surface 14c of the second side wall 14 is in a position retracted from the plane formed by the two flat portions (14a, 14b), and the depth of the dent does not cause contact with the curved portion 27. By doing so, it does not come into contact with the side surface portion of the cutting insert 20.

  Next, the effect of this embodiment will be described. When the cutting insert 20 is placed on the insert mounting seat 11, with respect to the first side wall 13, the concave curved side wall portion 13 a curved in an arc shape comes into contact with the curved portion 27 curved in the arc shape of the cutting insert 20 and is flat. The flat surface 13b does not come into contact with the surface portion 28a. In this way, even if the cutting insert 20 rotates on the insert mounting seat 11 due to friction between the screw 30 and the cutting insert 20 during screwing, the range in which the contact portion can move is the concave curved side wall portion 13a. The amount of movement of the contact portion is reduced. The same applies to the case where rotation occurs due to cutting resistance applied during cutting.

  On the other hand, if the abutting portions of the side surface of the cutting insert and the side surface of the insert mounting seat are both flat and are premised on the surface contact between them, the cutting insert is one of the side wall portions of the insert mounting seat. The end can be turned as a fulcrum. That is, the contact portion varies within the range of the length of the side wall portion and becomes very large.

  Further, in the body 10 applied to the cutting tool 100 as in the present embodiment, the concave curved side wall portion 13a that restricts the rotation at the time of screwing as described above is relatively positioned on the first side wall 13. It is advantageous to provide it. This is because the second side wall 14 located on the relatively proximal side functions as a portion that receives a considerable portion of the cutting resistance, as will be described below. However, the concave curved side wall portion can be provided on an appropriate side wall depending on the configuration of the cutting tool.

  On the other hand, with respect to the second side wall 14, flat portions 14 a and 14 b that are in contact with the cutting insert 20 are formed, and the curved receding surface 14 c that is a portion other than the flat portions 14 a and 14 b does not contact the cutting insert 20. Thus, even if various variations occur in the insert mounting seat 11 and the cutting insert 20, the cutting insert 20 always abuts against the flat portions 14a and 14b. That is, by providing the curved receding surface 14c, the position where the contact between the cutting insert 20 and the second side wall 14 can be accommodated in the flat portions 14a and 14b in a certain region. The various variations include manufacturing errors and the like in addition to variations in sliding due to friction between the screw and the cutting insert 20.

  In addition, when the curved receding surface 14c is formed at the center of the second side wall 14 and the two flat portions 14a and 14b) are formed in a balanced manner near the end of the second side wall, the cutting insert is stably restrained. Thus, the cutting insert 20 is prevented from moving or rotating due to the cutting resistance during the cutting process.

  As described above, since the variation in the position of the contact portion between each side wall and the cutting insert 20 is reduced, the fixed state of the cutting insert 20 is also constant, and the quality of the cutting process is also constant. Further, unlike Patent Document 1 in which the cutting insert 20 is formed with a concave portion on the side surface and abuts against the insert mounting seat at the side edge portion thereof, there is no thin portion that is liable to be damaged due to stress concentration. The strength of the cutting insert and thus the mounting stability is ensured.

  Since the radius of curvature of the curved portion 27 of the cutting insert 20 is smaller than the radius of curvature of the concave curved side wall portion 13a, the concave curved side wall portion 13a is elastically deformed with the contact with the curved portion 27, so that the first and Even if the angle and the positional relationship formed by the second side wall slightly change, the curved portion 27 is surely contained in the concave curved side wall portion 13a and the contact is maintained.

  As mentioned above, although one embodiment was described as an example about the present invention, it is possible to adopt another embodiment in the range which does not deviate from the meaning of the present invention. For example, in the above-described embodiment, the concave curved side wall portion 13a of the first side wall 13 is formed at the outer peripheral end of the first side wall 13, but the range in which the contact with the curved side surface portion included in the cutting insert is ensured. Thus, it may be formed on the center side of the first side wall 13. That is, the first side wall 13 may have not only the flat surface 13b on the body central axis side but also the flat surface 13c on the outer peripheral side as indicated by a two-dot chain line in FIG. However, the concave curved side wall portion 13a is preferably formed at a position biased toward the outer peripheral side in the first side surface 13 to which it belongs. More strictly speaking, when the concave curved side wall portion 13a is divided into two left and right regions with the center of the concave curved side wall portion 13a as a boundary, an outer peripheral side region 13a ′ positioned on the outer peripheral side of the body 10 (see FIG. 5). ) Is preferably located closer to the outer periphery of the tool than the center of the first side wall 13. That is, the cutting insert 20 with respect to the rotation that occurs in the clockwise direction in FIG. 5 when screwing is performed when the contact point with the cutting insert 20 is as close as possible to the outer peripheral side of the first side wall 13, that is, the side close to the opening. Is stably fixed, it is preferable that the concave curved side wall portion 13a be as close to the outer peripheral side as possible.

  In the embodiment described above, the cutting tool 100 was a cutting tool for shoulder cutting, but may be a cutting tool for other processing such as face cutting or high feed processing.

  In the above-described embodiment, the basic shape of the upper surface and the lower surface of the cutting insert is a triangle composed of three corners and three side ridges, but may be a quadrangle composed of four corners and four side ridges. Moreover, it is also possible to make it a polygon more than a pentagon. Even when a polygonal cutting insert having a square shape or more is attached, the side wall of the insert mounting seat includes a side wall portion corresponding to the side surface of each cutting insert. That is, the side wall of the insert mounting seat is formed so as to correspond to the outer shape of each shape of the cutting insert and to correspond to at least a part of the side surface serving as the contacted surface.

  The concave curved side wall portion 13a only needs to be concave, and there is no limit to the size of the radius of curvature. In the above embodiment, the concave curved side wall portion 13a has a radius of curvature larger than the radius of curvature of the curved portion 27 of the cutting insert 20, but both may have the same size. That is, the radius of curvature of the curved portion 27 of the cutting insert 20 may be equal to or less than the radius of curvature of the concave curved side wall portion 13a. Further, any curved surface shape may be used as long as the contact position between the curved surfaces is stable, and the circular arc shape or the elliptical arc shape can be used.

Claims (8)

A body (10) of a blade-tip-exchange-type cutting tool (100),
An insert mounting seat (11) for mounting a cutting insert (20) having a substantially polygonal end face (23, 24);
The insert mounting seat (11) includes a bottom surface (12) and side walls (13, 14),
The side walls (13, 14) are respectively in contact with two side surface portions (27, 28a, 28b) of two side surfaces of the cutting insert (20) connected to the end surfaces (23, 24). A second side wall (13, 14) having the first and second side walls (13, 14) relatively positioned on the front end side and the base end side of the body (10), respectively.
The first side wall (13) has a concave curved side wall portion (13a) curved so as to be recessed, and only the concave curved side wall portion (13a) contacts the side surface portion (27) of the cutting insert (20). contact and,
The second side wall (14) has a curved receding surface (14c) that curves and recedes in a concave shape, and flat surfaces (14a, 14b) formed on both sides thereof, and the cutting is performed only on the flat surface. A body (10) characterized in that it abuts against the side surface portions (28a, 28b) of the insert (20 ). The body (10) according to claim 1, wherein the concave curved side wall portion (13a) regulates a range in which the cutting insert (20) can rotate on the bottom surface (12). The body (10) has a generally cylindrical shape, and the side walls (13, 14) of the cutting insert (20) have openings that are open on the distal end side and the outer peripheral side of the cylindrical body (10). The body (10) according to claim 1 or 2 , wherein a mounting space is formed, and the concave curved side wall portion (13a) is provided at a position biased toward the outer peripheral side. The body (10) according to claim 3 , wherein the concave curved side wall portion (13a) is formed so that one end thereof faces the opening. Cutting insert (20) having a body (10) according to any one of claims 1 to 4 and a convex side surface portion (27) abutting against the concave curved side wall portion (13a) of the insert mounting seat (11). ), And a cutting edge exchangeable cutting tool (100). When viewed from the direction facing the bottom surface (12) of the insert mounting seat (11), the concave curved side wall portion (13a) is substantially arc-shaped,
When viewed from the direction facing the end surface (23) of the cutting insert (20), the convex side surface portion (27) is substantially arc-shaped,
The cutting edge exchangeable cutting tool (100) according to claim 5 , wherein a radius of curvature of the convex side surface portion (27) is equal to or less than a radius of curvature of the concave curved side wall portion (13a). When the cutting insert (20) is viewed from above, the cutting insert (20) includes three corners (21) and three side ridges (22) connecting the corners,
When the cutting insert (20) is viewed from the side, the side ridge portion (22) includes a concave curved side ridge portion that curves toward the lower surface, and the portion of the concave curved side ridge portion that is closest to the lower surface is The blade edge replacement according to claim 5 or 6 , wherein the blade edge replacement is within a region whose limit is a position 10% away from the center of the side ridge portion (22) to the left and right of the side ridge portion (22). Type cutting tool (100). The cutting edge replacement according to any one of claims 5 to 7 , wherein the cutting insert (20) has a 180-degree rotationally symmetric shape with respect to a rotation axis passing through a side surface of the cutting insert (20). Type cutting tool (100).

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