JP7749181B1 - Cutting tools and their tool bodies and core materials - Google Patents

Abstract

The present invention is particularly directed to drilling tools with large diameters, and makes it easy to provide a coolant discharge port at a desired position without forming a complicated flow path as in the past.
[Solution] A core member 20 detachably attached to a tool body 10 of a cutting tool has a coolant groove 28 provided at the base end of the core member 20 and a coolant flow path 29 that communicates from the coolant groove 28 to the tip end of the core member 20. The tool body 10 also has a core mounting portion into which the core member 20 is incorporated, a first coolant supply path 18A for supplying coolant from the base end 10b side toward the core mounting portion, and a second coolant supply path that communicates from an inner circumferential surface 11p of the core mounting portion to the tip end 10t of the tool body 10.
[Selected Figure] Figure 11

Description

The present invention relates to a cutting tool, its tool body, and core member.

Conventionally, large-diameter drilling tools include tools in which the insert seat for the central cutting insert is integrally formed with the head, and tools in which the pocket for the central cutting insert is mounted in a cartridge-type. Also known as such large-diameter drilling tools are those that have coolant flow paths inside them (see, for example, Patent Documents 1 to 3).

Chinese Patent No. 103909287 U.S. Patent No. 9,498,829 DE 102017209442

However, in large-diameter drilling tools, the outer diameter of the tool is larger than the hole diameter of the coolant passage located near the axial center of the tool body. Therefore, if a coolant outlet is to be located at a desired position from the coolant passage located near the axial center toward the cutting edge located at the tip of the tool, it becomes necessary to form flow passages that branch off in a complex manner from the coolant passage located near the axial center of the tool body, which tends to result in complex flow passages. For example, branching the flow passages may require the creation of holes that penetrate the outer surface of the tool, which can create issues such as the need for parts that are unnecessary for the tool's function to seal the through holes.

The present invention therefore aims to provide a cutting tool, tool body, and core member, particularly for large-diameter drilling tools, that makes it easy to provide a coolant outlet at the desired position without having to form complex flow paths as in the past.

One aspect of the present invention is a core member detachable from a tool body of a cutting tool, comprising:
a coolant groove provided at a base end of the core member along a central axis of the core member;
a coolant flow path communicating from the coolant groove to a tip end portion of the core member;
The core member has the following structure.

This type of core member is designed to allow coolant to be supplied from the base end to the tip end through a coolant flow path, making it possible to provide a coolant outlet at the desired location without having to form complex flow paths as in the past.

The above-mentioned core member may have multiple coolant grooves.

In the above-mentioned core member, the inlet of the coolant flow path may be provided on the bottom surface of the coolant groove.

In the above-mentioned core member, multiple coolant flow paths may be provided.

In the core member described above, a pair of coolant flow paths may be arranged symmetrically around the central axis.

In the above-described core member, the coolant flow path may be configured as a flow path that moves away from the central axis as it moves from the base end to the tip end.

The core member described above may have a spiral groove on its outer surface.

The core member described above may be cylindrical.

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

In the above-described core member, the insert seat may be arranged to surround the central axis.

The core member described above may also be a drill.

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 first coolant supply passage for supplying coolant from a base end side toward the core attachment portion;
a second coolant supply passage communicating from an inner peripheral surface of the core mounting portion to a tip end portion of the tool body;
The tool body includes:

In the above-described tool body, multiple second coolant supply passages may be provided.

In the tool body described above, a pair of second coolant supply passages may be arranged symmetrically around the central axis.

In the tool body described above, the second coolant supply passage may be configured as a flow path that moves away from the central axis as it moves from the base end to the tip end.

In the tool body described above, a spiral groove may be provided on the outer peripheral surface.

In the above-described tool body, the coolant discharge port may be positioned forward of the spiral groove in the direction of rotation of the tool body.

Another aspect of the present invention is a cutting tool comprising a core member and a tool body as described above, in which the second coolant supply passage is formed to communicate with the coolant groove of the core member when the core member is assembled in a predetermined orientation into the core mounting portion of the tool body.

1 is a perspective view showing a cutting tool according to an embodiment of the present invention. FIG. 1 is a perspective view showing an example of a drill head (tool body) of a cutting tool. FIG. 1 is a perspective view showing an example of a core member that can be attached to and detached from a drill head. FIG. 2 is an exploded perspective view showing a drill head, a core member, a cutting insert, etc. FIG. FIG. 1 is a view of a drill head and the like as seen from the tip end side. 6 is a cross-sectional view of the drill head and the like taken along line VI-VI in FIG. 5. FIG. 6B is an enlarged view of a portion of FIG. 6A. FIG. 2 is a perspective view showing an example of a core member. FIG. 10 is a view of the core member as seen from the tip end side. FIG. 6 is a cross-sectional view of the drill head and the core member taken along line X-X in FIG. 5 . FIG. 10 is a cross-sectional view of the drill head and the core member taken along line XI-XI in FIG. 5 . FIG. 11 is a perspective view of the drill head and core member with the cross section shown in FIG. 10; FIG. 10 is a perspective view of the core member with a central cutting edge (cutting insert) attached to the insert seat, as viewed from the tip end side. FIG. 2 is a perspective view of the core member as viewed from the base end side.

Below, we will explain in detail preferred embodiments of the cutting tool, its tool body, and core member according to the present invention, with reference to the drawings (see Figure 1, etc.).

The following describes a drilling tool 1 as an example of a preferred embodiment of the present invention (see Figure 1, etc.). The drilling tool 1 of this embodiment is configured as a tool including a tool body 10, a core member 20 that can be attached to and detached from the tool body 10, a fixing means 30, etc. (see Figure 4A, etc.).

[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 circumferential surface 13, a chip discharge groove 14, an insert seat 15, an extension attachment portion 16, a guide pad attachment portion 17, a coolant supply passage 18, and the like (see FIG. 4A , etc.).

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. This 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 external shape of the core member 20, e.g., a cylindrical shape, and a bottom surface 11b against which the base end 20b of the core member 20 abuts (see Figure 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 Figure 6A, etc.).

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 internally threaded to engage with the fixing screw (see Figure 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, penetrating from the outer periphery 13 of the tool body 10 to the inner periphery 11p of the core mounting portion 11 (see Figure 6A, etc.). When the fixing means 30 is passed through the obliquely provided through-hole 12 and pressed against the abutment surface 21 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. The angle α formed between the central 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 between the central axis 10x and the perpendicular line 21v to the abutment surface 21 on the imaginary plane formed by the central axis 10x and the center line 12c.

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 Figure 2, etc.). The opening of the through hole 12 is provided on the circumferential surface of the large diameter portion 13t (see Figure 6).

The chip discharge grooves 14 are grooves for discharging chips generated during cutting together with coolant. In the tool body 10 of this embodiment, two pairs of spiral chip discharge grooves 14 are provided on the outer peripheral surface 13, symmetrically about the central axis 10x (see Figure 5, etc.).

The insert seat 15 is a seat for attaching the cutting insert 50 to the tool body 10. The specific configuration of such an insert seat 15 and the cutting insert 50 attached thereto is not particularly limited, and multiple insert seats 15 may be provided radially outward from the core attachment portion 11. As an example, in this embodiment, a total of four insert seats 15 are arranged in a linear radial configuration, with two on either side of the central axis 10x (see Figure 5, etc.). Each of these insert seats 15 is designed to allow a cutting insert 50 to be attached in a predetermined orientation (see Figure 2, etc.).

The extension attachment/detachment section 16 is a section for attaching the extension 62 (see Figures 1, 2, etc.). Although not specifically shown, the adapter 60 may be attached directly to the extension attachment/detachment section 16 without the extension 62.

The guide pad mounting portion 17 is a portion provided for mounting the 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 cut by a cutting insert 50 or the like. The guide pad 70 is mounted to the guide pad mounting portion 17 and attached and fixed to the side (outer peripheral surface 13) of the tool body 10 by a set screw 72 (see Figure 2, etc.).

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 first coolant supply passage 18A is provided inside the tool body 10, extending straight along the central axis 10x from the base end 10b to the tip end 10t (see Figures 6 and 11). The tip end side of the first coolant supply passage 18A opens at the bottom surface 10b of the core mounting portion 11, and supplies coolant toward the coolant groove 28 in the core member 20.

The tool body 10 is further provided with a second coolant supply passage 18B and a coolant discharge port 19 (see FIG. 10). The second coolant supply passage 18B is provided to communicate from the inner circumferential surface 11p of the core mounting portion 11 of the tool body 10 to the tip end 10t of the tool body 10, and its specific configuration is not particularly limited. As an example, in the tool body 10 of this embodiment, two second coolant supply passages 18B are provided symmetrically about the central axis 10x (see FIGS. 10 and 12). Furthermore, these two second coolant supply passages 18B are configured to diverge from the central axis 10x as they extend from the base end 10b of the tool body 10 toward the tip end 10t (see FIGS. 10 and 12). In this case, the centrifugal force acting during rotation of the tool body 10 can also act as a force to send coolant toward the tip end 10t.

The coolant discharge ports 19 are outlets through which coolant that has flowed through the coolant supply passages 18 (first coolant supply passage 18A, second coolant supply passage 18B) is discharged. In the tool body 10 of this embodiment, the coolant discharge ports 19 are located in each of the two second coolant supply passages 18B, forward of the chip discharge grooves (spiral grooves) 14 in the direction of rotation of the tool body 10 (see Figures 4A and 5). The coolant discharged from the coolant discharge ports 19 located in this manner sends chips into the chip discharge grooves (spiral grooves) 14, making it easier for them to be discharged.

[Core member]
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 may be a so-called solid drill having an integrated cutting edge at its tip, or a replaceable-tip 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 shape (including a cylindrical shape) extending along the central axis 20x, and includes a contact surface 21, a spiral groove 22, an insert seat 23, a coolant groove 28, a coolant flow path 29, etc.

The abutment surface 21 is formed as a surface against 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, forming the abutment surface 21 in the cutout portion (see Figure 7, etc.). The core member 20 is assembled into the core mounting portion 11 along the central axis 10x of the tool body 10, and in this state, a portion of the fixing means 30 abuts against the abutment surface 21, thereby fixing the core member 20 to the tool body 10 (see Figure 3, etc.). The abutment surface 21 is inclined with respect to an imaginary plane (denoted by the symbol VP in Figure 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 Figure 9, etc.). The angle β between the central axis 20x of the core member 20 and the perpendicular line 21v of the abutment surface 21 is preferably 45° or more and less than 90° on the imaginary plane formed by the central axis 20x and the perpendicular line 21v (see the plane that appears as a cross section in Figure 6B) (see Figure 9). An example of a suitable range for the angle β is 74° or more and 76° or less.

In this embodiment, the abutment surface 21 is located near the base end 20b of the core member 20 (see Figure 7, etc.), but this is merely one example; conversely, it may be located near the tip end 20t, or near the center in the longitudinal direction along the central axis 20x. In addition, in this embodiment, the abutment surface 21 is configured as a flat surface (see Figure 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 specifically 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 is 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, in which the abutment surface 21 is convex and a portion of the fixing means 30 (the portion that abuts against the abutment surface 21) is concave to match this convex surface; alternatively, the abutment surface 21 may be convex and a portion of the fixing means 30 (the portion that abuts against the abutment surface 21) may be flat. In the latter case, the position where the fixing means 30 and the abutment surface 21 abut is less susceptible to manufacturing tolerances, allowing the core member 20 to be fixed precisely in the designed position.

The spiral groove 22 is composed of 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 20p, symmetrically about the central axis 20x (see Figure 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 portion 11, or to form a surface that smoothly connects with it (see Figure 2, etc.). Formed in this way, the chip discharge groove 14 has a shape without steps, which eliminates obstacles during chip discharge, improving chip discharge performance.

The insert seat 23 is provided at the tip 20t of the core member 20 so that the cutting insert (chip) 40 can be attached along the central axis 20x (see Figure 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 way, 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 tip side of the cutting insert 40, which functions as the central cutting edge of the drilling tool 1, has a rake face 41 that faces forward in the tool rotation direction, and a flank face 42 that faces the axial direction of the central axis 10x and moves away from the tip as it approaches the rear end in the tool rotation direction, and the intersection of the rake face 41 and flank face 42 forms the cutting edge 43 (see Figures 4A and 4B). Additionally, while an example has been shown here in which a single insert seat 23 is provided at the center of the drilling tool 1, other configurations are possible, such as an indexable drill, in which multiple insert seats 23 are arranged around the central axis 20x and indexable inserts are attached to these insert seats 23, although this is not specifically shown.

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, forming a flow path through which coolant flows (see FIG. 6A, etc.). The shape and structure of the coolant groove 28 are not particularly limited; for example, it may be formed as a single groove or multiple grooves. In the core member 20 of this embodiment, the coolant groove 28 is formed as two grooves, a first coolant groove 281 and a second coolant groove 282, which intersect in a crisscross pattern (see FIGS. 7, 13B, etc.). An inlet 29a of the coolant flow path 29 is provided in the bottom surface 281b of the first coolant groove 281. In the core member 20 of this embodiment, the two inlets 29a are arranged symmetrically about the central axis 20x (see FIGS. 11 and 13B).

The coolant flow passages 29 are, for example, multiple passages provided inside the core member 20, and guide the coolant that has flowed into the coolant groove 28 to the tip 20t and discharges it. In this embodiment, the coolant flow passages 29 in the core member 20 are composed of two passages that run from a portion of the coolant groove 28 (e.g., the bottom surface 281b of the first coolant groove 281) to the coolant discharge port 29e (see Figures 7, 8, 12, etc.). The pair of coolant discharge ports 29e are positioned to discharge coolant toward the cutting edge at the tip of the drilling tool 1 (e.g., the cutting edge of the cutting insert 40 that constitutes the central cutting edge) (see Figure 13A, etc.). In this embodiment, the two coolant flow passages 29 in the core member 20 are arranged symmetrically about the central axis 20x (see Figure 11, etc.). Furthermore, these coolant flow paths 29 are configured so that they gradually move away from the central axis 20x as they move from the base end 20b to the tip end 20t, essentially fanning out (see Figure 11).

The core member 20 of this embodiment, which has this structure, is capable of supplying coolant from the base end 20b to the tip end 20t through the coolant flow path 29 as described above. This makes it possible to provide a coolant discharge port 29e at the desired position without having to form a complex flow path as in the past.

[Fixing means]
The fixing means 30 is used to fix the core member 20 incorporated 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.). However, 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. For example, a biasing member utilizing elastic deformation (such as a spring member or a deformed portion of the tool body 10) may be used as a member other than a screw. 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.

[Drilling tools]
The drilling tool 1 of this embodiment is configured as a tool including the above-described tool body 10, the core member 20 detachably attached to the tool body 10, and the fixing means 30 (see FIG. 4A, etc.). When the core member 20 is assembled in a predetermined orientation into the core mounting portion 11 of the tool body 10 and fixed by the fixing means 30 (see FIG. 6A, etc.), the second coolant supply passage 18B communicates with the second coolant groove 282 in the coolant groove 28 of the core member 20 (see FIG. 10). A portion of the coolant supplied from the first coolant supply passage 18A flows into the second coolant supply passage 18B through the coolant groove 28 of the core member 20 and is discharged from the coolant discharge port 19.

According to the tool body 10, core member 20, fixing means 30, or the drilling tool 1 configured by these as described above, the fixing means 30 presses the outer 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, making it possible to more firmly fix the core member 20. In this regard, conventional large-diameter drilling tools that use cartridge-type insert seats for central cutting inserts have the advantage over non-cartridge-type tools that allow only the central cutting insert seat to be replaced if it is damaged. However, the cylindrical component 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 secured by pressing a flat surface parallel to the central axis of the component against the side of the component with the tip of a screw inserted into a threaded hole that extends 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 type of securing method, it must be said that forces parallel to the central axis of the component can only be withstood by the frictional force generated between the inner surface of the insertion hole and the outer surface of the component due to the pressing force of the screw. In contrast, the advantages of the drilling tool 1 of this embodiment are as described above.

Furthermore, with 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 then incorporated into the tool body 10, creating a so-called dual structure. This makes it easier to prevent damage or deformation to 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 machining under high-efficiency conditions or in unstable conditions.

While the above-described embodiment is one preferred example of the present invention, it is not intended to be limiting and various modifications are possible without departing from the spirit and scope 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 other materials (for example, a tipped drill with brazed tips of cemented carbide or other materials as cutting edges, or a core member 20).

Furthermore, while the above embodiment shows an example in which the present invention is applied to a drilling tool 1, 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.

Up to this point, we have explained the above-mentioned cutting tool (drilling tool) as an example of a double-structure cutting tool, but it is of course possible to apply the present invention to cutting tools that could be called triple-structure cutting tools. For example, the present invention can also be applied to cutting tools with a triple structure in which the core member 20 is a so-called solid drill in which a drill that serves as a central cutting edge is integrally formed at the tip 20t, and cutting inserts are arranged on its outer periphery (outside the central cutting edge), and this is further combined with the tool body 10.

The present invention is suitable for application to the tool body of a cutting tool and its core member.

1...Drilling tools (cutting tools)
10...Tool body 10b...Base end portion 10t...Tip portion 10x...Center axis 11...Core mounting portion 11b...Bottom surface 11p...Inner peripheral surface 12...Through hole 12c...(Through hole) center line 13...Outer peripheral surface 13b...Small diameter portion 13t...Large diameter portion 13m...Tapered portion 14...Chip discharge groove (spiral groove)
15...insert seat 16...extension attachment/detachment portion 17...guide pad attachment portion 18...coolant supply passage 18A...first coolant supply passage 18B...second coolant supply passage 19...coolant discharge port 20...core member 20b...base end portion 20p...outer peripheral surface 20t...tip portion 20x...center axis 21...abutment surface 21v...perpendicular to abutment surface 22...spiral groove 23...insert seat 23h...threaded hole 23s...fixing screw 28...(base end) coolant groove 281...first coolant groove 281b...bottom surface 282 (of first coolant groove)...second coolant groove 29...coolant flow passage 29a...coolant flow passage inlet 29e...coolant discharge port 30...fixing means 40...center cutting edge (cutting insert)
41...Cutting face 42...Flank face 43...Cutting edge 50...Cutting insert 60...Adapter 62...Extension 70...Guide pad 72...Set screw α...Angle β between the central axis 10x of the tool body 10 and the center line 12c of the through hole 12...Angle VP between the central axis 20x of the core member 20 and the perpendicular line 21v of the abutment surface 21...Imaginary plane (perpendicular to the central axis)

Claims (17)

A core member detachable from a tool body of a cutting tool,
a coolant groove provided at a base end of the core member along a central axis of the core member;
a coolant flow path communicating from the coolant groove to a tip end portion of the core member;
and
A core member having a plurality of the coolant grooves . The core member according to claim 1, wherein an inlet for the coolant flow path is provided on the bottom surface of the coolant groove. The core member according to claim 1, wherein multiple coolant flow paths are provided. 4. The core member according to claim 3 , wherein two of said coolant flow passages forming a pair are provided symmetrically about said central axis. 4. The core member according to claim 3 , wherein the coolant flow passage is configured as a flow passage that moves away from the central axis as it moves from the base end portion to the tip end portion. The core member according to claim 1 , wherein a spiral groove is provided on the outer peripheral surface. A core member detachable from a tool body of a cutting tool,
a coolant groove provided at a base end of the core member along a central axis of the core member;
a coolant flow path communicating from the coolant groove to a tip end portion of the core member;
and
A cylindrical core member. A core member detachable from a tool body of a cutting tool,
a coolant groove provided at a base end of the core member along a central axis of the core member;
a coolant flow path communicating from the coolant groove to a tip end portion of the core member;
and
A core member having an insert seat at its tip, on which a cutting insert is attached. The core member according to claim 8 , wherein the insert seat is disposed so as to surround the central axis. The core member according to any one of claims 1 to 5 , which is a drill. A tool body of a cutting tool to which a cutting insert and a drill can be detachably attached,
a core mounting portion into which a core member having a cutting edge is mounted along a central axis of the tool body;
a first coolant supply passage for supplying coolant from a base end side toward the core attachment portion;
a second coolant supply passage communicating from an inner peripheral surface of the core mounting portion to a coolant discharge port at a tip end of the tool body;
A tool body comprising: The tool body according to claim 11 , wherein a plurality of the second coolant supply passages are provided. The tool body according to claim 12 , wherein the pair of second coolant supply passages are provided symmetrically about the central axis. The tool body according to claim 12 , wherein the second coolant supply passage is configured as a flow passage that moves away from the central axis as it moves from the base end portion to the tip end portion. 15. A tool body according to any one of claims 11 to 14 , wherein the outer peripheral surface is provided with a spiral groove. The tool body according to claim 15 , wherein the coolant discharge port is disposed forward of the spiral groove in the rotation direction of the tool body. A cutting tool comprising the core member according to any one of claims 1 to 5 and the tool body according to any one of claims 11 to 14 ,
the second coolant supply passage is formed to communicate with the coolant groove of the core member when the core member is incorporated into the core mounting portion of the tool body in a predetermined orientation.