Turning Tool

Abstract

Provided is a lathing tool (1) that is less likely to interfere with another tool and can supply a sufficient amount of coolant. The lathing tool (1) is provided with: a cutting insert (10) that is mirror symmetric with respect to first and second symmetry surfaces (M1, M2); and a tool body (2) that has a first discharge port (5) for supplying a coolant from a first rake surface (21R) side onto a first cutting edge (21E) of the cutting insert (10). The first discharge port (5) is positioned between a second flat surface (32) and a first reference surface (Vxz) that is parallel to the second flat surface (32) and has a ridge line of the first cutting edge (21E).

Description

Turning tools

[0001] The present invention relates to a turning tool.

[0002] Turning tools mounted on a gang tool post of a machine tool that uses multiple turning tools arranged in parallel are spaced closely apart from adjacent turning tools. If a turning tool has a bulging portion in the Y-axis direction where the turning tools are adjacent, the bulging portion may interfere with an adjacent turning tool that has already been mounted on the gang tool post when the turning tool is attached to the gang tool post, making it impossible to attach the turning tool to the gang tool post. Furthermore, when machining a workpiece using an adjacent turning tool, the bulging portion may interfere with the workpiece and scratch the workpiece.

[0003] Patent Document 1 discloses a turning tool equipped with a nozzle portion (protruding portion 106) that supplies coolant to the cutting edge during grooving or parting-off, which cuts grooves into the outer peripheral surface of a cylinder. When coolant is sprayed at high pressure onto the cutting edge, chips can be broken down into smaller pieces and efficiently removed. Furthermore, the coolant supplied from the rake face side cools the rake face, thereby suppressing crater wear. The coolant supplied from the flank side lubricates the flank face, thereby suppressing notch wear.

[0004] However, in grooving and parting-off, the workpiece is driven by the spindle of the machine tool to rotate around the Z axis, and cutting is performed from the X-axis direction, which is the radial direction of the workpiece, so the flank faces the X-axis direction and the rake face faces the Y-axis direction. In the turning tool described in Patent Document 1, the nozzle portion that supplies coolant from the rake face side protrudes in the Y-axis direction from the shank portion of the tool body.

[0005] Therefore, Patent Document 2 discloses a turning tool in which the angle of the nozzle outlet is changed at the expense of the amount of coolant supplied. As in Patent Document 2, if the direction of coolant flow connecting the cutting edge and the outlet is not approximately in a straight line, the turning tool can be configured so that the nozzle does not protrude from the shank. However, there is a risk that a sufficient amount of coolant may not be supplied to the cutting edge.

[0006] JP 2016-55360 A JP 2003-71608 A

[0007] The present invention has been made in view of the above-mentioned problems, and has an object to provide a turning tool that is less likely to interfere with other tools and is capable of supplying a sufficient amount of coolant.

[0008] A turning tool according to one aspect of the present invention includes an exchangeable cutting insert and a tool body for fixing the cutting insert. The cutting insert has mirror symmetry with respect to a first plane of symmetry perpendicular to the central axis of the mounting hole, and further has mirror symmetry with respect to a second plane of symmetry including the central axis. The cutting insert has a front surface, a back surface opposite the front surface, a peripheral side surface connecting the front surface and the back surface, and a mounting hole penetrating the front surface and the back surface. The peripheral side surface is formed parallel to the central axis. The peripheral side surface includes a first cutting edge portion having a first cutting edge parallel to the central axis and a first rake face and a first flank face facing the first cutting edge; a second cutting edge portion having a second cutting edge parallel to the central axis and a second rake face and a second flank face facing the second cutting edge, mirror-symmetric to the first cutting edge with respect to a second symmetry plane; a base end portion on the opposite side to the tip end portion where the first cutting edge and the second cutting edge are provided; a third flat surface continuous with the first rake face; a first flat surface connecting the third flat surface and one end of the base end portion; the tool body includes an insert mounting seat for fixing the cutting insert with the second flat surface oriented parallel to the longitudinal direction of the tool body when the first cutting edge is usable, and a first discharge port for supplying coolant from the first rake face side toward the first cutting edge when the first cutting edge is usable. The first discharge port is located between the second flat surface and a first reference plane that is parallel to the second flat surface and includes the ridge line of the first cutting edge.

[0009] According to this aspect, since the first discharge port is located more inward of the tool body than the cutting edge of the first cutting edge in the direction in which the turning tools are adjacent to each other, the portion where the first discharge port is provided is less likely to protrude from the shank portion of the tool body, thereby making it possible to provide a turning tool that is less likely to interfere with other tools.

[0010] In the above aspect, the third flat surface may be inclined so as to approach the second flat surface as it approaches the base end, and the fourth flat surface, which is mirror-symmetric to the third flat surface with respect to the second plane of symmetry, may be inclined so as to approach the first flat surface as it approaches the base end.

[0011] According to this aspect, the space between the first reference surface and the third flat surface is increased by the amount of inclination of the third flat surface, making it easier to supply coolant directly from the first outlet to the first cutting edge. This increases the amount of coolant that can be supplied to the first cutting edge, making it possible to provide a turning tool that can supply a sufficient amount of coolant.

[0012] In the above aspect, the orientation of the first outlet may be configured so that, when the first cutting edge portion is in a usable state, the trajectory of the coolant from the first outlet toward the first cutting edge is approximately parallel to the third flat surface.

[0013] As the third flat surface is inclined, it becomes easier to supply coolant, while the wedge angle of the cutting edge of the first cutting portion becomes smaller. According to this aspect, the third flat surface is not inclined more than necessary and is parallel to the trajectory along which coolant is supplied directly from the first outlet to the first cutting edge. Because the third flat surface is inclined at a minimum angle, it is easy to supply coolant directly from the first outlet to the first cutting edge, and it is easy to ensure a large wedge angle at the cutting edge of the first cutting portion.

[0014] In the above aspect, the second discharge port may be located closer to the base end of the tool body than the second cutting edge.

[0015] According to this aspect, since the cutting insert is fixed with the second flat surface oriented parallel to the longitudinal direction of the tool body, the first cutting edge portion and the second cutting edge portion are not in the same position in the longitudinal direction of the tool body, and the first cutting edge portion is recessed further toward the base end of the tool body than the second cutting edge portion. Because the position directly below the first cutting edge portion, which receives the main component of cutting resistance, can be brought closer to the insert mounting seat, the second outlet port, which supplies coolant from approximately directly below the first cutting edge portion, can also be formed in a position recessed further toward the base end than the second cutting edge. Since the second outlet port does not need to protrude beyond the cutting insert at the tip of the tool body, the tool body can be configured more compactly in the longitudinal direction.

[0016] According to the present invention, it is possible to provide a turning tool that is less likely to interfere with other tools and that can supply a sufficient amount of coolant.

[0017] Fig. 1 is a perspective view showing an example of a turning tool according to an embodiment of the present invention. Fig. 2 is a perspective view showing the internal structure of the turning tool shown in Fig. 1 . Fig. 3 is a front view of the turning tool shown in Fig. 1 as seen from the tip side. Fig. 4 is a side view of the turning tool shown in Fig. 1 as seen from the front surface side of the cutting insert. Fig. 5 is a perspective view of the second discharge port shown in Fig. 2 as seen from the back surface side of the cutting insert. Fig. 6 is a plan view of the second discharge port shown in Fig. 5 as seen from a direction parallel to the rotation axis of the spindle of the machine tool.

[0018] A preferred embodiment of the present invention will be described with reference to the accompanying drawings. In each drawing, components with the same reference numerals have the same or similar configurations. Each configuration will be described in detail below with reference to Figs. 1 to 6. Fig. 1 is a perspective view showing an example of a turning tool 1 according to an embodiment of the present invention. The turning tool 1 according to an embodiment of the present invention is attached to a gang tool post or the like of a machine tool and is used for grooving and parting-off.

[0019] As shown in Fig. 1, an indexable turning tool 1 includes an exchangeable cutting insert 10 and a tool body 2 to which the cutting insert 10 is fixed, and is used by being fixed to a tool post or the like. When a plurality of turning tools including the turning tool 1 are attached to a gang tool post of a machine tool and used, the turning tools are arranged in parallel so as to be adjacent to each other in the Y-axis direction in Fig. 1. As seen by an operator, the X-axis direction, which is the longitudinal direction of the tool body 2, coincides with, for example, the up-down direction, the Y-axis direction in which the turning tools 1 are adjacent coincides with, for example, the front-to-back direction, and the Z-axis direction, which is parallel to the rotation axis of the workpiece, coincides with, for example, the left-to-right direction.

[0020] 2 is a perspective view showing the internal structure of the turning tool 1 shown in FIG. 2. As shown in FIG. 2, the tip portion of the tool body 2, including the tip 2D of the tool body 2 and its vicinity, is provided with an insert mounting seat 3 recessed in a shape conforming to the cutting insert 10, and first and second outlets 5, 6 for supplying coolant to the cutting insert 10 fixed to the insert mounting seat 3. The first outlet 5 supplies coolant from the side of a first rake face 21R (described later) toward the first cutting edge 21E, and the second outlet 6 supplies coolant from the side of a first flank face 21F (described later) toward the first cutting edge 21E. Supplying coolant from the first and second outlets 5, 6 improves chip removal and cools the first cutting edge 21E.

[0021] In the tool body 2, the shank portion 4, which constitutes the base end 2P on the opposite side to the tip 2D to the tip portion described above, is formed in a rectangular prism shape with no bulging portion in the Y-axis direction. A coolant flow path is formed inside the shank portion 4, which communicates with the first and second outlets 5, 6. The coolant may be supplied by connecting a hose to the base end 2P of the tool body 2, or may be supplied directly from the tool post without a hose.

[0022] The cutting insert 10 is fixed to the insert mounting seat 3 by a clamping screw or the like (not shown) so that the central axis O of the mounting hole 19 is in the Z-axis direction and one of a second flat surface 32 and a first flat surface 31 (described later) is parallel to the XZ plane. The cutting insert 10 has a front surface (first main surface) 11, a back surface (second main surface) 12 opposite the front surface 11, a peripheral side surface 13 connecting the front surface 11 and the back surface 12, a mounting hole 19 penetrating the front surface 11 and the back surface 12, and first and second cutting edges 21, 22 formed on the peripheral side surface 13. The first cutting edge 21 is used with the back surface 12 facing the insert mounting seat 3, and the second cutting edge 22 is used by flipping it over so that the front surface 11 faces the insert mounting seat 3.

[0023] 1 is a front view of the turning tool 1 as viewed from the tip 2D side of the tool body 2. As shown in Fig. 3, the cutting insert 10 has mirror symmetry with respect to a first plane of symmetry M1 that is perpendicular to the central axis O of the mounting hole 19. The first plane of symmetry M1 is parallel to the XY plane, is positioned equidistant from the front surface 11 and the back surface 12, and divides the plate thickness of the cutting insert 10 into two equal parts.

[0024] The front surface 11 and the back surface 12 are partitioned into a thick region 14 where the thickness of the front surface 11 and the back surface 12 is greater, and a thin region where the thickness is smaller than the thick region 14. The mounting hole 19 (shown in FIG. 2) is formed in the thick region 14. The first and second cutting edges 21, 22 are formed in the thin region 15.

[0025] Fig. 4 is a side view of the turning tool 1 shown in Fig. 1 as viewed from the front surface 11 side of the cutting insert 10. As shown in Fig. 4, the cutting insert 10 has mirror symmetry with respect to a second plane of symmetry M2 including the central axis O. The second plane of symmetry M2 is orthogonal to the XY plane and intersects with the YZ plane at an angle of, for example, 20°, and is positioned equidistant from the first and second cutting edges 21, 22, dividing the front surface 11 and the back surface 12 into two equal parts.

[0026] Referring again to Fig. 2, the cutting insert 10 has a peripheral side surface 13 formed parallel to the central axis O. In addition to the first and second cutting edges 21, 22 described above, the peripheral side surface 13 further includes a base end portion 30 opposite to the tip end portions (21, 22) where the first and second cutting edges 21, 22 are formed, first and third flat surfaces 31, 33 connecting the base end portion 30 and the first cutting edge portion 21, second and fourth flat surfaces 32, 34 connecting the base end portion 30 and the second cutting edge portion 22, and a connecting surface 35 connecting the first cutting edge portion 21 and the second cutting edge portion 22.

[0027] Each of the first to fourth flat surfaces 31, 32, 33, and 34 has a base end close to the base end 30 and a tip end close to the tip end (21, 22), and is formed as a flat plane from the base end to the tip end. The base end 30 is formed as part of a cylindrical surface and has one end 30A and the other end 30B opposite the one end. The connection surface 35 is formed as a curved surface recessed toward the base end 30, and has one end 35A and the other end 35B opposite the one end.

[0028] The first cutting portion 21 is composed of a first cutting edge 21E parallel to the central axis O, and a first rake face 21R and a first flank face 21F facing the first cutting edge 21E. Similarly, the second cutting portion 22 is composed of a second cutting edge 22E parallel to the central axis O, and a second rake face 22R and a second flank face 22F facing the second cutting edge 22E. The ridge line where the first rake face 21R and the first flank face 21F intersect is the first cutting edge 21E, and the ridge line where the second rake face 22R and the second flank face 22F intersect is the second cutting edge 22E.

[0029] A tip 33D of the third flat surface 33 is continuous with the first cutting face 21R of the first cutting portion 21. The first flat surface 31 connects the base end 33P of the third flat surface 33 to one end 30A of the base end portion 30. Similarly, a tip 34D of the fourth flat surface 34 is continuous with the second cutting face 22R of the second cutting portion 22. The second flat surface 32 connects the base end 34P of the fourth flat surface 34 to the other end 30B of the base end portion 30. Each of the first and second flat surfaces 31, 32 is formed across a portion of the circumferential side surface 13 facing the thick-walled region 14 and a portion of the circumferential side surface 13 facing the thin-walled region 15.

[0030] When R-chamfering or C-chamfering is performed at the boundary between the first flat surface 31 and the third flat surface 33, the position of the tip 31D of the first flat surface 31 and the base end 33P of the third flat surface 33 is the midpoint between the start point and end point where the curvature of the R-chamfer changes, and is the midpoint between one ridge line and the other ridge line of the C-chamfer. Similarly, the position of the tip 32D of the second flat surface 32 and the base end 34P of the fourth flat surface 34 is the midpoint of the surface chamfered with R-chamfering or C-chamfering.

[0031] The front surface 11 and the back surface 12 are mirror-symmetric with respect to the first plane of symmetry M1. The first cutting edge 21E, the first rake face 21R, and the first flank face 21F constituting the first cutting portion 21, and the second cutting edge 22E, the second rake face 22R, and the second flank face 22F constituting the second cutting portion 22 are mirror-symmetric with respect to the second plane of symmetry M2. Similarly, the first and second flat surfaces 31 and 32 are mirror-symmetric with respect to the second plane of symmetry M2, and the third and fourth flat surfaces 33 and 34 are mirror-symmetric with respect to the second plane of symmetry M2.

[0032] That is, the rear surface 12, the second cutting edge 22, and the second and fourth flat surfaces 32, 34 each have substantially the same shape and function as the front surface 11, the first cutting edge 21, and the first and third flat surfaces 31, 33. Therefore, the first cutting edge 21 and the first and third flat surfaces 31, 33 will be described in detail as representatives, and redundant descriptions of the second cutting edge 22 and the second and fourth flat surfaces 32, 34 may be omitted.

[0033] Referring again to FIG. 4 , one of the turning tool 1 of this embodiment is characterized in that either the second flat surface 32 or the first flat surface 31, rather than the second symmetry plane M2 of the cutting insert 10, is configured to be parallel to the longitudinal direction X of the tool body 2. As shown in FIG. 4 , the first rake face 21R includes the ridgeline of the first cutting edge 21E, i.e., the ridgeline where the first rake face 21R and the first flank face 21F intersect, and has a positive rake angle α1 with respect to a first reference plane Vxz parallel to the second flat surface 32. The first flank face 21F includes the ridgeline of the first cutting edge 21E, i.e., the ridgeline where the first rake face 21R and the first flank face 21F intersect, and has a positive clearance angle β1 with respect to a third reference plane Vyx that is perpendicular to the second flat surface 32 or a virtual plane (second virtual plane) Q extending from the second flat surface 32.

[0034] Similarly, the second rake face 22R, which is mirror-symmetric to the first rake face 21R about the second symmetry plane M2, includes the ridgeline of the second cutting edge 22E, i.e., the ridgeline where the second rake face 22R and the second flank face 22F intersect, and has a positive rake angle α2 with respect to the second reference plane Wxz parallel to the first flat surface 31. The second flank face 22F, which is mirror-symmetric to the first flank face 21F about the second symmetry plane M2, includes the ridgeline of the second cutting edge 22E, i.e., the ridgeline where the second rake face 22R and the second flank face 22F intersect, and has a positive clearance angle β2 with respect to the fourth reference plane Wyz that is perpendicular to the first flat surface 31 or a virtual plane (first virtual plane) P extending from the first flat surface 31.

[0035] The imaginary planes P and Q intersect at an intersection angle γ of approximately 30 to 45°. In the illustrated example, the intersection angle γ is 40°. The distance d1 from the intersection line T where the imaginary planes P and Q intersect to the central axis O of the mounting hole 19 is longer than the distance d2 from the ridge line of the first cutting edge 21E of the first cutting portion 21 to the central axis. Since the distance d2 between the clamping screw that secures the cutting insert 10 and the first cutting portion 21 or the second cutting portion 22, on which the principal component of the cutting resistance acts, is short, the turning tool 1 has excellent rigidity.

[0036] The third flat surface 33 is inclined toward the second flat surface 32 toward the base end 30, and the fourth flat surface 34, which is mirror-symmetric to the third flat surface 33 with respect to the second plane of symmetry M2, is inclined toward the first flat surface 31 toward the base end 30. The intersection angle δ between the imaginary planes P and R can be changed as appropriate as long as the first flank has a positive clearance angle β1 and the wedge angle (90°-α1-β1) of the cutting edge of the first cutting portion 21 does not become extremely small. When the intersection angle γ between the imaginary planes P and Q is around 40°, the intersection angle δ is, for example, 100° to 160°, preferably 135° to 160°. In the illustrated example, the intersection angle δ is 150°.

[0037] One of the features of the turning tool 1 of this embodiment is that the first outlet 5, which supplies coolant from the first rake face 21R toward the first cutting edge 21E, is located between the first reference surface Vxz and the second flat surface 32. In the illustrated example, the third flat surface 33 is inclined so that it approaches the second flat surface 32 as it approaches the base end 30, which increases the space between the first reference surface and the third flat surface through which the coolant can advance. This makes it easy to supply coolant directly from the first outlet 5 to the first cutting edge 21E.

[0038] When the third flat surface 33 is inclined relative to the second flat surface 32, it is preferable that the direction of the flow path 5C of the first outlet 5 is configured so that, when the first blade portion 21 is in a usable state, the trajectory of the coolant from the first outlet 5 toward the first cutting edge 21E is approximately parallel to the third flat surface 33, so that the wedge angle of the cutting edge of the first blade portion 21 does not become too small.

[0039] Alternatively, the third flat surface 33 may be formed parallel to the second flat surface 32, and the fourth flat surface 34 may be formed parallel to the first flat surface 31. When the third flat surface 33 is parallel to the second flat surface 32, the first outlet 5 located between the second flat surface 32 and the first reference plane Vxz cannot supply coolant directly to the first cutting edge 21E. Therefore, the direction of the flow path 5C of the first outlet 5 may be changed so that coolant is sprayed toward the workpiece rotating toward the first cutting face 21R, and the coolant reflected upon impact with the workpiece is supplied to the first cutting face 21R.

[0040] Fig. 5 is a perspective view of the second discharge port 6 shown in Fig. 2 as viewed from the back surface 12 side of the cutting insert 10. As shown in Fig. 5, the second discharge port 6 is provided substantially directly below the first cutting edge 21E and supplies coolant to the first cutting edge 21E from the first flank 21F side. Fig. 6 is a side view of the second discharge port 6 shown in Fig. 5 as viewed from a direction parallel to the rotation axis of the spindle of the machine tool. As shown in Fig. 6, a flow path 6C is formed to supply coolant to the second discharge port 6 from the tip 2D of the tool body 2 toward the base end 2P. The tip of the flow path 6C is closed with a hexagon socket set screw or the like.

[0041] As described above, in the turning tool 1 of this embodiment, the cutting insert 10 is fixed so that the second flat surface 32 is oriented parallel to the X-axis direction, which is the longitudinal direction of the tool body 2. Therefore, as shown in Fig. 6, the first cutting edge portion 21 and the second cutting edge portion 22 are not at the same position in the X-axis direction, and the first cutting edge portion 21 is set back further toward the base end 2P of the tool body 2 than the second cutting edge portion 22. The second outlet 6 that supplies coolant from approximately directly below the first cutting edge portion 21 can also be formed at a position set back further toward the base end 2P than the second cutting edge portion 22, allowing the length of the tool body 2 to be compact in the X-axis direction.

[0042] According to the turning tool 1 of this embodiment configured as described above, the cutting insert 10 is formed with the third and fourth flat surfaces 33, 34 that have an intersection angle δ with the first and second flat surfaces 31, 32. Therefore, the turning tool 1 can be arranged so that either the second flat surface 32 or the first flat surface 31, rather than the second plane of symmetry M2, is parallel to the longitudinal direction X of the tool body 2. Because the first cutting portion 21 is recessed toward the base end 2P of the tool body 2 relative to the second cutting portion 22 and the distance from the insert mounting seat 3 is reduced, the turning tool 1 can be configured with greater rigidity than when the second plane of symmetry M2 is parallel to the longitudinal direction X of the tool body 2. In the Y-axis direction, the first outlet 5 that supplies coolant from the first rake face 21R to the first cutting edge 21E is located more inward on the tool body 2 than the cutting edge of the first cutting edge 21E. Therefore, the portion where the first outlet 5 is provided is less likely to protrude beyond the shank portion 4 of the tool body. This makes it possible to provide a turning tool 1 that is less likely to interfere with other tools.

[0043] The above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The elements of the embodiments, as well as their arrangement, materials, conditions, shapes, sizes, etc., are not limited to those illustrated and can be modified as appropriate. Furthermore, configurations shown in different embodiments can be partially substituted or combined with each other.

[0044] 1... Turning tool, 2... Tool body, 2D... Tip, 2P... Base end, 3... Insert mounting seat, 4... Shank portion, 5... First outlet, 6... Second outlet, 5C, 6C... Flow path, 10... Cutting insert, 11... Surface, 12... Back surface, 13... Peripheral side surface, 14... Thick region, 15... Thin region, 19... Mounting hole, 21... First cutting edge portion, 21E... First cutting edge, 21F... First relief surface, 21R... First rake face, 22... Second cutting edge portion, 22E... Second cutting edge, 22F... Second relief surface, 22R... Second rake face, (21, 22)... Tip portion, 30... Base end portion, 30A... One end, 30B... Other end, 31... First flat surface , 31D...other end, 31P...one end, 32...second flat surface, 32D...other end, 32P...one end, 33...third flat surface, 33D...other end, 33P...one end, 34... Fourth flat surface, 34D... Other end, 34P... One end, 35... Connection surface, 35A... One end, 35B... Other end, d1, d2... Distance, M1... First symmetry plane , M2...Second plane of symmetry, O...Central axis, P, Q, R...Virtual plane, T, U...Intersection line, Vxz...First reference plane, Vyx...Third reference plane, Wxz...Second reference surface, Wyz...fourth reference plane, X...vertical direction, Y...front / back direction, Z...horizontal direction, α1, α2...rake angle, β1, β2...relief angle, γ, δ...intersection angle.

Claims

1. A turning tool comprising an exchangeable cutting insert and a tool body for fixing the cutting insert, wherein the cutting insert has mirror symmetry about a first plane of symmetry perpendicular to the central axis of a mounting hole, and further has mirror symmetry about a second plane of symmetry including the central axis, and has a front surface, a back surface opposite to the front surface, a peripheral side surface connecting the front surface and the back surface, and the mounting hole penetrating the front surface and the back surface, the peripheral side surface being formed parallel to the central axis, and the peripheral side surface further comprising: a first cutting edge portion consisting of a first cutting edge parallel to the central axis and a first rake face and a first flank face facing the first cutting edge; a second cutting edge portion which is mirror symmetrical to the first cutting edge about the second plane of symmetry and consists of a second cutting edge parallel to the central axis and a second rake face and a second flank face facing the second cutting edge; and a base end portion opposite to a tip end portion at which the first cutting edge and the second cutting edge are provided. a third flat surface continuous with the first cutting surface; a first flat surface connecting the third flat surface and one end of the base portion; a fourth flat surface continuous with the second cutting surface, which is a mirror image of the third flat surface with respect to the second plane of symmetry; and a second flat surface connecting the fourth flat surface and the other end of the base portion, which is a mirror image of the first flat surface with respect to the second plane of symmetry; wherein the tool body has: an insert mounting seat that fixes the cutting insert in an orientation in which the second flat surface is parallel to the longitudinal direction of the tool body when the first cutting edge portion is in a usable state; and a first discharge port that supplies coolant from the first cutting surface side toward the first cutting edge when the first cutting edge portion is in a usable state, and the first discharge port is located between the second flat surface and a first reference plane that is parallel to the second flat surface and includes a ridge line of the first cutting edge.

2. A turning tool according to claim 1, wherein the third flat surface is inclined so as to approach the second flat surface as it approaches the base end, and the fourth flat surface, which is mirror-symmetric to the third flat surface with respect to the second plane of symmetry, is inclined so as to approach the first flat surface as it approaches the base end.

3. A turning tool as described in claim 1 or 2, wherein the orientation of the first outlet is configured so that, when the first cutting edge portion is in a usable state, the trajectory of the coolant from the first outlet toward the first cutting edge is approximately parallel to the third flat surface.

4. A turning tool as claimed in any one of claims 1 to 3, wherein the tool body further has a second outlet port that supplies coolant from the first relief surface side to the first cutting edge when the first cutting edge portion is in a usable state, and the second outlet port is located closer to the base end of the tool body than the second cutting edge.

Images