Tool body and its core material for cutting tools

Abstract

To more firmly fix a member serving as a central blade. [Solution] The tool body (10) of the cutting tool comprises a core mounting portion (11) into which a cutting insert (40) and a core member (20) are fitted along a central axis (10x) of the tool body (10), and a fixing means (30) that fixes the core member (20) fitted into the core mounting portion (11) to the tool body (10). The core member (20) has an abutment surface (21) against which the fixing means (30) abuts. The abutment surface (21) is provided on an outer peripheral surface (20p) of the core member (20) so as to face outward and be inclined with respect to an imaginary plane perpendicular to the central axis of the core member (20). The fixing means (30) presses the outer peripheral surface (20p) of the core member (20) in a direction inclined with respect to an imaginary plane perpendicular to the central axis of the core member (20).

Description

[Technical Field]

[0001] The present invention relates to a tool body of a cutting tool and a core member thereof. [Background technology]

[0002] Conventionally, known large-diameter drilling tools include tools in which an insert seat for mounting an insert that serves as a central cutting edge is integrally formed with the head (see, for example, Patent Documents 1 and 2), and tools in which an insert seat for mounting an insert that serves as a central cutting edge is of a cartridge type (see, for example, Patent Documents 3 and 4). Also known as particularly large-diameter drilling tools is one in which a solid drill is positioned at the center of the tool and several inserts are further combined. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 8,376,669 [Patent Document 2] U.S. Patent No. 10,967,441 [Patent Document 3] U.S. Patent No. 7,244,081 [Patent Document 4] U.S. Patent No. 9,643,259 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the drilling tool described above, it is believed that there is still room for improvement in terms of more firmly fixing the member that serves as the central cutting edge.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a tool body of a cutting tool and a core member thereof that can more firmly fix a member that serves as a central cutting edge. [Means for solving the problem]

[0006] One aspect of the present invention is a core member detachable from a tool body of a cutting tool, comprising: a contact surface on which a fixing means for fixing the core member to a tool body abuts; The contact surface is a core member provided on the outer peripheral surface of the core member so as to face outward and be inclined with respect to an imaginary plane perpendicular to the central axis of the core member.

[0007] With such a core member, the contact surface against which the fixing means for fixing the core member to the tool body abuts is inclined, which generates a component force in a direction along the central axis, making it possible to more firmly fix the member that becomes the central blade (cutting insert) or the core member to which it is attached.

[0008] In the core member as described above, the contact surface may be inclined so as to face the tip end side of the core member.

[0009] In the core member as described above, the abutment surface may be provided on the base end side of the core member.

[0010] In the core member as described above, a spiral groove may be provided on the outer peripheral surface.

[0011] The core member as described above may be cylindrical.

[0012] In the core member as described above, an insert seat for mounting a cutting insert may be provided at the tip portion.

[0013] In the core member as described above, the insert seat may be arranged so as to surround the central axis.

[0014] The core member may be a drill.

[0015] In the core member as described above, the abutment surface may be a surface that abuts on a fixing means for fixing the core member to the tool body in a state where the core member is incorporated into the core mounting portion of the tool body along the central axis of the tool body.

[0016] In the core member as described above, the contact surface may be formed as a flat surface.

[0017] In the core member as described above, the contact surface may be configured to include a surface that includes at least a curved surface in part.

[0018] In the core member as described above, the angle formed between the central axis of the core member and a perpendicular line to the contact surface may be 45° or more and less than 90° on an imaginary plane formed by the central axis and the perpendicular line.

[0019] In the core member as described above, the angle formed by the central axis of the core member and the perpendicular to the contact surface may be 74° or more and 76° or less on an imaginary plane formed by the central axis and the perpendicular.

[0020] Another aspect of the present invention is a tool body of a cutting tool to which a cutting insert and a drill can be removably attached, comprising: a core mounting portion into which a core member having a cutting edge is mounted along a central axis of the tool body; a fixing means for fixing the core member incorporated in the core mounting portion to the tool body; Equipped with The fixing means is a tool body that presses the outer peripheral surface of the core member in a direction inclined with respect to an imaginary plane perpendicular to the central axis of the core member.

[0021] According to this tool body, the fixing means presses the outer peripheral surface of the core member in a direction inclined with respect to a virtual plane perpendicular to the central axis of the core member, thereby generating a component force in a direction along the central axis, and making it possible to fix the core member more firmly.

[0022] The tool body as described above may have a drill provided at the tip.

[0023] The tool body as described above may further include a through hole for passing the fastening means therethrough.

[0024] In the tool body as described above, the through-hole may be inclined so as to approach the tip end side as it moves radially outward of the tool body.

[0025] The tool body as described above may have a chip discharge groove formed in a spiral shape on the outer circumferential surface.

[0026] In the tool body as described above, the angle formed between the central axis and the center line of the through hole may be equal to or greater than 45° and less than 90° on an imaginary plane formed by the central axis and the center line.

[0027] In the tool body as described above, the angle formed between the central axis and the center line of the through hole may be 74° or more and 76° or less on an imaginary plane formed by the central axis and the center line.

[0028] In the tool body as described above, a core mounting portion may be provided along the central axis, and a plurality of insert seats may be provided radially outward from the core mounting portion.

[0029] A cutting tool according to yet another aspect of the present invention includes the above-described core member and a tool body.

[0030] In the cutting tool as described above, the angle formed by the central axis and the center line of the through hole may be the same as the angle formed by the central axis and a perpendicular line to the abutment surface on an imaginary plane formed by the central axis and the center line. [Brief explanation of the drawings]

[0031] [Figure 1] 1 is a perspective view showing a cutting tool according to an embodiment of the present invention. [Figure 2] FIG. 1 is a perspective view showing an example of a drill head (tool body) of a cutting tool. [Figure 3]FIG. 1 is a perspective view showing an example of a core member that can be attached to and detached from a drill head. [Figure 4A] FIG. 2 is an exploded perspective view showing a drill head, a core member, a cutting insert, etc. [Figure 4B] FIG. [Figure 5] FIG. 1 is a view of a drill head and the like as seen from the tip end side. [Figure 6A] 6 is a cross-sectional view of the drill head and the like taken along line VI-VI in FIG. 5. [Figure 6B] FIG. 6B is an enlarged view of a portion of FIG. 6A. [Figure 7] FIG. 2 is a perspective view showing an example of a core member. [Figure 8] FIG. 10 is a view of the core member as seen from the tip end side. [Figure 9] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, preferred embodiments of a tool body and a core member of a cutting tool according to the present invention will be described in detail with reference to the drawings (see FIG. 1, etc.).

[0033] A drilling tool 1 will be described below as an example of a preferred embodiment of the present invention (see FIG. 1, etc.). The drilling tool 1 of this embodiment is configured as a tool including a tool body 10, a core member 20 detachable from the tool body 10, a fixing means 30, etc. (see FIG. 4A, etc.).

[0034] Tool Body The tool body 10 is formed as a member to which the cutting insert 50 and the drill can be detachably attached, and functions as a so-called drill head when the cutting tool is the drilling tool 1 as in this embodiment. The tool body 10 of this embodiment has a shape that extends along a central axis 10x from a base end 10b to a tip end 10t, and is provided with a core attachment portion 11, a through hole 12, an outer peripheral surface 13, a chip discharge groove 14, an insert seat 15, an extension attachment / detachment portion 16, a guide pad attachment portion 17, a coolant supply passage 18, and the like (see FIG. 4A, etc.).

[0035] The core mounting portion 11 is provided at the tip end 10t of the tool body 10 so that the core member 20 is fitted along the central axis 10t. The core mounting portion 11 is formed as a circular hole having an inner peripheral surface 11p formed along the central axis 10x to match the outer shape of the core member 20, for example, a cylindrical shape, and a bottom surface 11b against which the base end 20b of the core member 20 abuts (see FIG. 6A, etc.). The core member 20 fitted into the core mounting portion 11 is fixed to the tool body 10 by fixing means 30 (see FIG. 6A, etc.).

[0036] The through hole 12 is provided as a hole for installation, such as by passing the fixing means 30 through it, and can take various forms depending on the specific example of the fixing means 30. For example, in this embodiment, a fixing screw is used as the fixing means 30, and the inner periphery of the through hole 12 is provided with an internal thread that screws into the fixing screw (see FIG. 4A, etc.). In this embodiment, the through hole 12 has a center line 12c that is oblique to the central axis 10x and is inclined toward the tip end 10t as it extends radially outward from the tool body 10, and penetrates from the outer circumferential surface 13 of the tool body 10 to the inner circumferential surface 11p of the core mounting portion 11 (see FIG. 6A, etc.). When the fixing means 30 is passed through the obliquely provided through hole 12 and pressed against the abutment surface 21 provided on the outer periphery of the core member 20, a component force along the central axis 10x acts in addition to a radial force. Therefore, the fixing means 30 not only applies a force pressing the core member 20 against the inner peripheral surface 11p, but also applies a force pressing the core member 20 against the bottom surface 11b of the core mounting portion 11 along the central axis 10x, so that the fixing means 30 presses the core member 20 toward the base end portion 10b along the axial direction and presses it against the bottom surface 11b, thereby more firmly fixing or holding the core member 20 (see FIG. 6B ). As long as the tool body 10 has such a structure, the angle α formed between the central axis 10x of the tool body 10 and the center line 12c of the through hole 12 is not particularly limited. However, in order to achieve the above-mentioned function, it is preferable that the angle α be 45° or more and less than 90°, and more preferably 74° or more and 76° or less, on the imaginary plane formed by the central axis 10x and the center line 12c.

[0037] The outer peripheral surface 13 of the tool body 10 has a large diameter portion 13t near the tip end 10t, a small diameter portion 13b closer to the base end 10b, and a tapered portion 13m connecting the large diameter portion 13t and the small diameter portion 13b (see FIG. 2, etc.). An opening of the through hole 12 is provided on the outer peripheral surface of the large diameter portion 13t (see FIG. 6).

[0038] The chip discharge grooves 14 are grooves for discharging chips generated during cutting together with coolant. In the tool body 10 of this embodiment, a pair of two spiral chip discharge grooves 14 are provided on the outer circumferential surface 13 so as to be axially symmetrical with respect to the central axis 10x (see FIG. 5, etc.).

[0039] The insert seat 15 is a seat for mounting the cutting insert 50 to the tool body 10. The specific aspects of such an insert seat 15 and the cutting insert 50 mounted therein are not particularly limited, and a plurality of insert seats 15 may be provided radially outward of the core mounting portion 11. As an example, in this embodiment, a total of four insert seats 15 are arranged linearly in the radial direction, with two on either side of the central axis 10x (see FIG. 5, etc.). Each of these insert seats 15 is configured to mount a cutting insert 50 in a predetermined orientation (see FIG. 2, etc.).

[0040] The extension detachable portion 16 is a portion for attaching the extension 62 (see FIGS. 1 and 2, etc.). Although not specifically shown, the adapter 60 may be attached directly to the extension detachable portion 16 without the extension 62.

[0041] The guide pad mounting portion 17 is a portion provided for mounting a guide pad 70. The guide pad 70 is a member that functions as a guide by contacting the inner wall surface of a hole in a workpiece that has been cut by the cutting insert 50 or the like. The guide pad 70 is mounted on the guide pad mounting portion 17 and is attached and fixed to the side portion (outer peripheral surface 13) of the tool body 10 by a set screw 72 (see FIG. 2, etc.).

[0042] The coolant supply passage 18 is a flow path provided to supply coolant to the cutting edge at the tip of the drilling tool 1 (for example, the cutting edge of the cutting insert 40 that constitutes the central cutting edge). In the tool body 10 of this embodiment, a circular coolant passage 18 extending straight along the central axis 10x from the base end 10b to the tip end 10t is provided inside the tool body 10 (see FIG. 6). The tip end 10t side of the coolant passage 18 opens at the bottom surface 10b of the core mounting portion 11, and coolant is supplied toward the coolant groove 28 of the core member 20.

[0043] [Core material] The core member 20 is a steel member (steel body) that can be attached to and detached from the core attachment portion 11 of the tool body 10 (see FIGS. 3 to 9). The core member 20 can be a so-called solid drill with an integrated cutting edge at its tip, or a replaceable cutting edge or replaceable head member. As an example, in this embodiment, a core member 20 having a replaceable head structure will be described. The core member 20 of this embodiment has a substantially cylindrical or columnar shape extending along the central axis 20x, and includes an abutment surface 21, a spiral groove 22, an insert seat 23, a coolant groove 28, a coolant flow path 29, etc.

[0044] The abutment surface 21 is formed as a surface with which a portion of the fixing means 30 abuts. In this embodiment, a portion of the outer peripheral surface 20p of the core member 20 is cut out, and the abutment surface 21 is formed in the cutout portion (see FIG. 7, etc.). The core member 20 is assembled into the core attachment portion 11 along the central axis 10x of the tool body 10, and in this state, a portion of the fixing means 30 is brought into abutment with the abutment surface 21, thereby fixing the core member 20 to the tool body 10 (see FIG. 3, etc.). The abutment surface 21 is inclined with respect to an imaginary plane (indicated by the symbol VP in FIG. 6) perpendicular to the central axis 20x of the core member 20, and is provided so as to face outward and toward the tip end 20t of the core member 20 (see FIG. 9, etc.). It is preferable that the angle β formed by the central axis 20x of core member 20 and the perpendicular line 21v of abutment surface 21 is 45° or more and less than 90° on an imaginary plane (see the plane that appears as a cross section in FIG. 6B) formed by central axis 20x and perpendicular line 21v (see FIG. 9). An example of a preferable range for angle β is 74° or more and 76° or less.

[0045] In this embodiment, such abutment surface 21 is provided near the base end 20b of the core member 20 (see FIG. 7, etc.), but this is merely an example, and conversely, it may be provided near the tip end 20t, or near the center in the longitudinal direction along the central axis 20x. Also, in this embodiment, the abutment surface 21 is configured as a flat surface (see FIG. 9, etc.), but for example, this abutment surface 21 may be configured as a surface that includes at least a partial curved surface. Although not particularly shown, for example, by configuring the abutment surface 21 as a concave surface and configuring a portion of the fixing means 30 (the portion abutting the abutment surface 21) as a convex surface that matches this concave surface, it becomes possible to perform autonomous alignment or centering when the fixing means 30 is pressed against the abutment surface 21. Although not specifically shown, the opposite structure may be used, that is, the abutment surface 21 may be configured as a convex surface and a portion of the fixing means 30 (the portion that abuts against the abutment surface 21) may be configured as a concave surface that matches this convex surface, or the abutment surface 21 may be configured as a convex surface and a portion of the fixing means 30 (the portion that abuts against the abutment surface 21) may be configured as a flat surface. In the latter case, the position where the fixing means 30 and the abutment surface 21 abut is less susceptible to the influence of manufacturing tolerances, and the core member 20 can be fixed precisely in the designed position.

[0046] The spiral groove 22 is formed by a groove spirally provided on the outer periphery of the core member 20. In the core member 20 of this embodiment, two pairs of spiral grooves 22 are provided on the outer periphery surface 20p so as to be axially symmetrical with respect to the central axis 20x (see FIG. 8, etc.). Furthermore, the spiral groove 22 is formed so as to smoothly connect with the chip discharge groove 14 of the tool body 10 when the core member 20 is assembled into the core mounting part 11, or to form a surface that smoothly connects with it (see FIG. 2, etc.). Because the chip discharge groove 14 is formed in this way and has a shape without steps, there are no obstacles when chips are discharged, which improves chip discharge performance.

[0047] The insert seat 23 is provided at the front end portion 20t of the core member 20 so that the cutting insert (chip) 40 can be attached along the central axis 20x (see FIG. 4A, etc.). A threaded hole 23h is provided near the insert seat 23, through which a fixing screw 23s for fixing the cutting insert 40 passes. In this manner, the cutting insert 40 attached to the insert seat 23 along the central axis 20x functions as the central cutting edge of the drilling tool 1. The front end of the cutting insert 40, which functions as the central cutting edge of the drilling tool 1, has a rake face 41 facing forward in the tool rotation direction and a flank face 42 facing in the axial direction of the central axis 10x and gradually moving away from the front end as it approaches the rear end in the tool rotation direction, and the intersection of the rake face 41 and the flank face 42 forms a cutting edge 43 (see FIGS. 4A and 4B). Furthermore, although an example has been shown here in which a single insert seat 23 is provided at the center of the drilling tool 1, other embodiments are possible, such as an indexable drill, which is not specifically shown, in which multiple insert seats 23 are arranged around the central axis 20x and indexable inserts are attached to these insert seats 23.

[0048] The coolant groove 28 is provided in the base end 20b of the core member 20. When the core member 20 is assembled into the core mounting portion 11 of the tool body 10, the coolant groove 28 communicates with the coolant supply passage 18 of the tool body 10 to form a flow path through which the coolant flows (see FIG. 6A, etc.). The shape and structure of the coolant groove 28 are not particularly limited, and may be formed, for example, as a single groove or as two grooves intersecting in a crisscross shape (see FIG. 7, etc.).

[0049] The coolant flow passage 29 is a flow passage provided inside the core member 20, which guides the coolant that has flowed into the coolant groove 28 to the tip end 20t and discharges it. The coolant flow passage 29 in the core member 20 of this embodiment is composed of two flow passages that continue from a part of the coolant groove 28 (for example, its bottom surface) to the coolant discharge port 29e (see Figures 7, 8, etc.). The pair of coolant discharge ports 29e are positioned to discharge the coolant toward the cutting edge at the tip of the drilling tool 1 (for example, the cutting edge of the cutting insert 40 that forms the central cutting edge).

[0050] [Fixing means] The fixing means 30 is used to fix the core member 20 assembled in the core mounting portion 11 of the tool body 10. As described above, in this embodiment, a fixing screw is used as the fixing means 30 (see FIG. 6A, etc.), but this is one example of a suitable means for fixing the core member 20, and it goes without saying that a member other than a screw may also be used. As a member other than a screw, for example, a biasing member that utilizes elastic deformation (a spring member, a deformed portion of the tool body 10, etc.) may also be used. Furthermore, the form of the through-hole 12 can be appropriately changed (for example, changed to a structure in which a biasing member is housed in a non-through hole) in accordance with the form of the fixing means 30.

[0051] According to the above-described tool body 10, core member 20, and fixing means 30, or the drilling tool 1 configured by these, the fixing means 30 presses the outer peripheral surface 20p of the core member 20 in a direction inclined with respect to an imaginary plane VP perpendicular to the central axis 20x of the core member 20, thereby generating a component force in a direction along the central axis 10x of the tool body 10 or the central axis 20x of the core member 20, and it is possible to fix the core member 20 more firmly. In this regard, conventional large-diameter drilling tools with cartridge-type insert seats for central cutting inserts have the advantage over non-cartridge-type tools that the insert seat for the central cutting edge can be replaced if the insert seat for the central cutting edge is damaged. However, the cylindrical part that serves as the central cutting edge is sometimes inserted into an insertion hole located at the center of the axial tip of the drilling tool body and fixed by pressing a flat surface parallel to the central axis of the part against the side of the part with the tip of a screw inserted into a threaded hole that runs perpendicular to the central axis of the tool body from the outer surface of the tool body to the inner surface of the insertion hole. With this fixing method, it must be said that forces parallel to the central axis of the part can only be withstood by the friction force generated between the inner surface of the insertion hole and the outer surface of the part due to the pressing force of the screw. In contrast, the advantages of the drilling tool 1 of this embodiment are as described above. In addition, the angle α formed by the center axis 10x of the tool body 10 and the center line 12c of the through hole 12 may be the same as the angle formed by the center axis 10x and the perpendicular line 21v of the abutment surface 21 on the imaginary plane formed by the center axis 10x and the center line 12c.

[0052] Furthermore, according to the drilling tool 1 of this embodiment, a replaceable central blade (cutting insert 40) is incorporated into the core member 20, and the core member 20 is incorporated into the tool body 10, creating a so-called double structure, which makes it easier to prevent damage or deformation of the tool body 10 itself, and also makes it possible to firmly fix the core member 20 to the tool body 10, making it easier to demonstrate stable cutting performance even when processing under high-efficiency conditions or in unstable conditions.

[0053] While the above-described embodiment is one example of a preferred embodiment of the present invention, it is not limited to this and various modifications are possible without departing from the spirit of the present invention. For example, the drilling tool 1 described in the above embodiment is a so-called indexable tool with a dual structure in which the core member 20 is detachably attached to the tool body (drill head) 10 and the central cutting edge (cutting insert 40) is detachably attached to the core member 20. However, this is merely one preferred example, and it goes without saying that the present invention can also be applied to other structures, such as tools with brazed tips of cemented carbide or the like (for example, a tipped drill with brazed tips of cemented carbide or other materials as cutting edges, or the core member 20).

[0054] In the above embodiment, the present invention is applied to the drilling tool 1, but this is merely one example of a cutting tool to which the present invention can be applied. In addition to drilling tools (drills), the present invention can also be applied to milling tools such as end mills.

[0055] Although the above description has been given using the cutting tool (drilling tool) having a so-called double structure as an example, the present invention can also be applied to a cutting tool having a so-called triple structure. For example, the present invention can also be applied to a cutting tool having a so-called triple structure in which the core member 20 is a so-called solid drill in which a drill serving as a central cutting edge is integrally provided at the tip portion 20t, and cutting inserts are disposed on the outer periphery (outside the central cutting edge) of the solid drill, and this is further combined with the tool body 10. [Industrial Applicability]

[0056] The present invention is suitably applied to a tool body of a cutting tool and its core member. [Explanation of symbols]

[0057] 1...Drilling tools (cutting tools) 10...Tool body 10b...Proximal end 10t...Tip 10x…center axis 11...Core mounting part 11b…Bottom surface 11p…Inner peripheral surface 12...Through hole 12c...(through hole) center line 13...Outer surface 13b…Small diameter part 13t...large diameter section 13m...Tapered section 14...Chip discharge groove 15...insert seat 16...Extension attachment / detachment part 17...Guide pad attachment part 18...Coolant supply passage 20...Core member 20b...Proximal end 20p…outer surface 20t...Tip 20x…center axis 21...Abutment surface 21v...perpendicular to the contact surface 22...Spiral groove 23...insert seat 23h...screw hole 23s...Fixing screw 28...Coolant groove (at base end) 29e...Coolant outlet 30...Fixing means 40...Central cutting edge (cutting insert) 41...Scooping surface 42...flank 43...Cutting edge 50...Cutting insert 60...Adapter 62...Extension 70...Guide pad 72...Set screw α: Angle between the central axis 10x of the tool body 10 and the center line 12c of the through hole 12 β: Angle between the central axis 20x of the core member 20 and the perpendicular line 21v of the contact surface 21 VP...imaginary plane (perpendicular to the central axis)

Claims

1. A cutting tool, a tool body to which a cutting insert and a drill can be attached and detached; a core member detachable from the tool body; a core mounting portion into which the core member having a cutting edge is mounted along a central axis of the tool body; a fixing means for fixing the core member incorporated in the core mounting portion to the tool body; a contact surface with which the fixing means contacts; Equipped with the abutment surface is provided on the outer peripheral surface of the core member so as to face outward at an angle with respect to an imaginary plane perpendicular to the central axis of the core member, The fixing means presses the outer peripheral surface of the core member in a direction inclined with respect to an imaginary plane perpendicular to the central axis of the core member, so as to abut the outer peripheral surface of the core member against the inner peripheral surface of the core mounting portion and abut the base end of the core member against the bottom surface of the core mounting portion.

2. The cutting tool according to claim 1 , wherein the abutment surface is provided on a base end side of the core member.

3. The cutting tool according to claim 1 , wherein a spiral groove is provided on the outer peripheral surface of the core member.

4. The cutting tool of claim 1 , wherein the core member is cylindrical.

5. The cutting tool according to claim 1 , wherein an insert seat for mounting a cutting insert is provided at a tip end portion of the core member.

6. The cutting tool according to claim 5 , wherein the insert seat is disposed so as to surround a central axis of the core member.

7. The cutting tool of claim 1 , wherein the core member is a drill.

8. The cutting tool according to claim 1 , wherein the contact surface is configured as a flat surface.

9. The cutting tool according to claim 1 , wherein the contact surface is configured as a surface that includes a curved surface at least in part.

10. The cutting tool according to claim 1 , wherein a coolant groove is provided at a base end of the core member.

11. The cutting tool according to claim 1 , wherein a guide pad is attached to a guide pad attachment portion on the circumferential surface of the tool body.

12. The cutting tool according to claim 1 , further comprising a through-hole in the tool body for passing the fixing means therethrough.

13. The cutting tool according to claim 12 , wherein the through-hole is inclined so as to approach a tip end of the tool body as it extends radially outward from the tool body.

14. The cutting tool according to claim 1 , wherein a chip discharge flute formed in a spiral shape is provided on an outer peripheral surface of the tool body.

15. 14. The cutting tool according to claim 13, wherein an angle formed between a central axis of the tool body and a center line of the through hole is equal to or greater than 45° and less than 90° on an imaginary plane formed by the central axis and the center line.

16. 14. The cutting tool according to claim 13, wherein an angle formed between a central axis of the tool body and a center line of the through hole is equal to or greater than 74° and equal to or less than 76° on an imaginary plane formed by the central axis and the center line.

17. The cutting tool according to claim 1 , wherein the core mounting portion is located along the central axis, and a plurality of insert seats are located radially outward of the core mounting portion.

18. 13. The cutting tool according to claim 12, wherein an angle formed between a central axis of the tool body and a center line of the through hole is the same as an angle formed between the central axis and a perpendicular line to the abutment surface on an imaginary plane formed by the central axis and the center line.

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