Cutting tool for hole drilling and tool body of the same

Abstract

To sufficiently supply a coolant to a tool tip side.SOLUTION: A tool body 10 of a hole drilling cutting tool 1 equipped with an insert fitting seat 20 to which a cutting insert 60 is fitted comprises: a cut chip discharge hole 30 formed from the insert fitting seat 20 toward a tip side 10t from the base end side 10b of the tool body 10; and a coolant flow path 40 for supplying a coolant from the base end side 10b of the cool body 10 toward the tip side 10t. The coolant flow path 40 has a through-hole 41 formed from the outer peripheral surface 14 of the tool body 10 toward the tip side 10t.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cutting tool for drilling holes and a tool body thereof. [Background technology]

[0002] When drilling holes using a rotary cutting tool such as a tool for BTA (Boring & Trepanning Association) machining, it is necessary to supply coolant toward the cutting edge of the cutting insert provided at the tip of the body (hereinafter referred to as the "tool body" in this specification) (see, for example, Patent Documents 1 and 2). In this regard, conventional cutting tools are generally configured to supply coolant toward the cutting edge from an oil supply groove provided on the outer periphery of the tool body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2003-502163 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-66678 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in cutting tools for drilling holes such as those described above, because they are configured with a chip discharge hole with an opening called a chip mouth, most of the coolant supplied from the base end of the tool body tends to be discharged from the chip mouth before reaching the tip end of the tool. In particular, BTA tools often use viscous, water-insoluble cutting oil as the coolant, making it difficult for the coolant to reach the cutting edge.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a cutting tool for drilling holes and a tool body thereof that allow coolant to be supplied sufficiently to the tip of the tool. [Means for solving the problem]

[0006] To solve these problems, the present inventors conducted extensive research into the structure and characteristics of cutting tools for drilling holes. For example, in BTA tools, chips and coolant are discharged through the interior of the pipe (tube)-shaped tool body, so supplying coolant from the outer periphery of the pipe (tube) is a common-sense technique, and BTA tools are based on this premise. However, with this structure, most of the coolant supplied from the outer periphery is sucked into the chip discharge hole (the opening called the chip mouth) without reaching the tip, making it difficult for the coolant to reach the cutting edge. After extensive research into this structure and its problems, the present inventors have arrived at insights that lead to a solution to these problems.

[0007] One aspect of the present invention, which has been arrived at based on such findings, is a tool body of a cutting tool for drilling a hole, which is provided with an insert mounting seat to which a cutting insert is attached, comprising: The tool body has a chip discharge hole formed from the insert mounting seat toward the base end side of the tool body, and a coolant flow path that supplies coolant from the base end side toward the tip end side of the tool body, The coolant flow path is a tool body of a cutting tool for drilling holes, which has a through hole extending from the outer circumferential surface of the tool body toward the tip side.

[0008] In the tool body of the cutting tool for hole drilling described above, the coolant flow path is provided with a through hole extending from the outer circumferential surface of the tool body toward the tip, which allows sufficient coolant to be supplied to the tip of the tool through the through hole, including the amount that would have been sucked into the chip discharge hole in the past. Increasing the amount of coolant supplied to the tip of the tool in this way leads to improved lubrication and cooling performance, particularly around the cutting edge, during cutting using a cutting tool having the tool body.

[0009] In the tool body of the cutting tool for hole drilling according to the above aspect, the through-hole may penetrate all the way to the end face on the tip side of the tool body.

[0010] In the tool body of the cutting tool for hole drilling having the above-described configuration, the through hole may branch midway.

[0011] In the tool body of the cutting tool for hole machining of the above aspect, the tip-side opening of the through-hole in the tip-side end face may be substantially circular with an arc, substantially elliptical, or substantially trapezoidal.

[0012] The tool body of the cutting tool for hole drilling of the above-described embodiment may have a plurality of through holes.

[0013] In the tool body of the cutting tool for hole drilling of the above aspect, the plurality of through holes may be arranged in a circumferential direction along the outer circumferential surface of the tool body.

[0014] In the tool body of the cutting tool for hole machining having the above-described configuration, the chip discharge hole is formed radially inward from the outer peripheral surface of the tool body, and the base-end opening, which is the opening on the base end side of the through hole, may be located on the base end side of the opening that serves as the chip inlet on the tip end side of the chip discharge hole.

[0015] In the tool body of the cutting tool for hole drilling of the above-described aspect, the chip discharge hole may be made up of a plurality of holes that join together midway from the tip end side to the base end side.

[0016] The tool body of the cutting tool for hole machining having the above-described configuration may include a cylindrical connecting portion and a large-diameter portion formed at the tip side of the connecting portion and having a larger diameter than the connecting portion, and the through hole may be provided so that at least a portion of it passes through the large-diameter portion.

[0017] In the tool body of the cutting tool for hole machining of the above aspect, the base end side opening of the through hole may be provided in the tapered portion between the connecting portion and the large diameter portion.

[0018] Another aspect of the present invention is a cutting tool for drilling holes, comprising the tool body and a cutting insert as described above.

[0019] Yet another aspect of the present invention is a cutting tool for drilling holes, comprising: a chip discharge hole formed from a tip end side to a base end side of the cutting tool; a coolant flow path that supplies coolant from a base end side to a tip end side of the cutting tool; It is equipped with The coolant flow passage is a cutting tool for drilling holes, which has a through hole extending from the outer circumferential surface of the cutting tool toward the tip side.

[0020] The cutting tool for drilling holes as described above may be a brazed tool having a tip brazed to the leading end thereof. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a perspective view showing a cutting tool for drilling a hole according to an embodiment of the present invention, as viewed from the tip side. [Figure 2] FIG. 2 is a perspective view of the cutting tool as viewed from the tip side. [Figure 3] 3A and 3B are diagrams showing the shapes of coolant channels and chip discharge holes formed in a cutting tool; [Figure 4] FIG. 2 is a view of the cutting tool as seen from the tip side. [Figure 5] FIG. 5 is a diagram of the cutting tool as seen from above in FIG. 4. [Figure 6] 1A and 1B are diagrams showing the results of a simulation analysis of the coolant flow in the cutting tool of the present embodiment and a conventional cutting tool, respectively. DETAILED DESCRIPTION OF THE INVENTION

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a cutting tool for drilling holes according to the present invention will be described in detail below with reference to the drawings (see FIG. 1, etc.).

[0023] The cutting tool 1 for drilling holes is a tool having an insert mounting seat 20 on a tip end side (indicated by reference symbol 10t) of a tool body (hereinafter also referred to as a "drill head") 10. The drill head 10 is substantially cylindrical and is formed to extend along a central axis 10A from a base end side (indicated by reference symbol 10b) to a tip end side 10t.

[0024] The drill head 10 of the cutting tool 1 of this embodiment has a connecting portion 15, a large-diameter portion 16, and a tapered portion 17, and is further provided with a chip discharge hole 30 and a coolant flow path 40 (see FIGS. 1 and 2, etc.). The connecting portion 15 is cylindrical, and its interior is a space that forms part of the chip discharge hole 30 through which chips and coolant C are discharged. A large-diameter portion 16, which is larger in diameter than the connecting portion 15, is formed at the tip side of the connecting portion 15. A tapered portion 17, which has a tapered outer peripheral surface, is formed between the connecting portion 15 and the large-diameter portion 16 (see FIG. 5, etc.). In addition, the outer peripheral surface of the cylindrical connecting portion 15 is provided with a male thread (not shown) that screws into a female thread of a drill pipe (not shown) and attaches the drill head 10 to the drill pipe.

[0025] The chip discharge hole 30 is formed radially inward of the outer peripheral surface 14 of the drill head 10 from the vicinity of the insert mounting seat 20 on the tip side 10t toward the base side 10b of the drill head 10 (see FIG. 1, etc.). The tip side 10t of the drill head 10 has a portion called a chip pocket, and openings (also called chip mouths) 31 and 32 of the chip discharge hole 30 are provided at the rear end of this chip pocket. The chip pocket is the portion that opens to the outer periphery of the drill head 10, and the chip discharge hole 30 begins where a wall is formed on the outer periphery of the drill head 10. In the cutting tool 1 of this embodiment, two openings, one large and one small, are provided on the tip surface 12 (see FIG. 4). The chip discharge holes 30 continuing from the two openings 31 and 32 that serve as chip inlets join at a position closer to the base side 12b than the tip surface 12 (see FIGS. 1, 3, etc.).

[0026] The coolant flow path 40 is a flow path formed to supply coolant from the base end side 10b of the drill head 10 toward the tip end side 10t. In this embodiment, a through hole 41 extending from the outer peripheral surface 14 of the drill head 10 toward the tip end side 10t is provided through the large diameter portion 16 of the drill head 10. As will be described later, this through hole 41 constitutes a part of the coolant flow path 40. A base end opening 42 of the through hole 41 is provided in the tapered portion 17 (see FIG. 2), and a tip end opening 43 is provided in the tip end surface 12 of the drill head 10 (see FIGS. 1 and 4). The base end opening 42 may have a shape that allows the coolant C to easily flow into the through hole 41 when the cutting tool 1 is rotating and cutting. For example, the base end opening 42 may have a shape that is inclined while extending toward the tip end 10 with respect to the central axis 10A, or may have a shape that extends circumferentially (see FIG. 2).

[0027] A plurality of through holes 41 may be provided. The plurality of through holes 41 may be arranged circumferentially along the outer peripheral surface 14 of the drill head 10. In this embodiment, two through holes 41A, 41B are provided in the drill head 10. These two through holes 41A, 41B are provided on either side of the central axis 10A in a portion of the drill head 10 where no chip discharge holes 30 exist (see FIG. 1, etc.). Furthermore, tip-side openings 43A, 43B, which are openings on the tip side 10t of each of these two through holes 41A, 41B, are provided on either side of the central axis 10A in a portion of the tip surface 12 of the drill head 10 where no openings 31, 32 of the chip discharge holes 30 exist (see FIG. 4).

[0028] The through hole 41 may have a branched shape along the way. In this embodiment, one of the through holes 41B has a branched shape along the way to the tip side 10t (see FIG. 3, etc.). The tip side opening 43B of this through hole 41B is composed of two opening holes corresponding to the branched flow paths (holes) respectively (see FIGS. 1 and 4). By branching the through hole 41 in this way along the way, it is possible to increase the flow rate of the coolant C while maintaining the rigidity of the cutting tool 1 or its drill head 10.

[0029] The tip-side opening 43A of the through hole 41A and the tip-side opening 43B of the through hole 41B are preferably configured so as not to significantly affect the strength of the drill head 10, particularly at the tip end 10t. In the cutting tool 1 of this embodiment, the tip-side opening 43B of the through hole 41B is smaller in opening area than the tip-side opening 43A of the through hole 4A and is circular, thereby minimizing the effect on strength. The tip-side opening 43A of the through hole 41A has a shape that takes into consideration the shape of the area in which the tip-side opening 43A is formed—more specifically, the shapes of the openings 31 and 32 of the chip discharge hole 30, the shapes of the adjacent insert mounting seat 20, cutting insert 60, and guide pad 80, and the distances therebetween—for example, a substantially circular shape with an arc, a substantially oval shape, or a substantially trapezoidal shape (see FIG. 4, etc.).

[0030] Furthermore, the base-end opening 42A, which is an opening on the base-end side 10b of the through hole 41A, and the base-end opening 42B, which is an opening on the base-end side 10b of the through hole 41B, are located closer to the base end 10b than the openings 31, 32 on the tip end side 10t of the chip discharge hole 30 (see FIG. 5, etc.). According to the cutting tool 1 in which the base-end openings 42 (42A, 42B) of the through holes 41 (41A, 41B) constituting a part of the coolant flow path 40 are located closer to the base end 10b than the openings 31, 32 of the chip discharge hole 30, the through hole 41 is structured to connect the tip end 10t of the drill head 10 of the cutting tool 1 from behind the chip discharge hole 30, enabling more effective supply of coolant to the tip end 10t. Furthermore, with this cutting tool 1, the amount of coolant C that cannot reach the cutting edge 61 and is sucked in through the openings (chip mouths) 31, 32 is reduced.

[0031] Cutting inserts 60 and guide pads 80 are detachably attached to the tip side 10t of the drill head 10 of the cutting tool 1 (see FIG. 1, etc.). The specific arrangement and form of these cutting inserts 60 and guide pads 80 are not particularly limited, but as an example, in the cutting tool 1 of this embodiment, two cutting inserts 60 are attached to the opening 31 of the chip discharge hole 30, and one cutting insert 60 is attached to the opening 32 with insert mounting screws 70, and guide pads 80 are attached to the outer peripheral surface 14 near the tip side 10t at positions radially outward from the cutting inserts 60 at the opening 32 and at positions near the tip side opening 43Bn (see FIG. 4, etc.). More specifically, in the cutting tool 1 of this embodiment, which is provided with three cutting inserts 60 and has cutting edges 61 arranged in three locations, it is difficult to balance the cutting force using only the cutting edges 61, and taking into consideration that the cutting force when two cutting inserts 60 are lined up tends to be larger (compared to when there is only one cutting insert 60), guide pads 80 are arranged in both an approximately 90° direction (in this embodiment, the downward direction in Figure 4) and an approximately 180° direction (in this embodiment, the left side direction in Figure 4) to stabilize the machining diameter, to absorb the force.

[0032] In the cutting tool 1 of this embodiment as described above, the coolant C supplied from the base end side 10b flows outside the connection portion 15 (in other words, the cylindrical gap between the cutting tool 1 and the workpiece (workpiece)) toward the tip end side 10t, flows from the base end openings 42 (42A, 42B) into the through holes 41 (41A, 41B), and flows out of the tip end openings 43 (43A, 43B) without being sucked into the chip discharge holes 30. In this way, the coolant C flowing through the through holes 41 (41A, 41B) and flowing out of the tip end openings 43 (43A, 43B) can more reliably reach the cutting edge 61 of the cutting insert 60.

[0033] As described above, according to the cutting tool 1 of this embodiment, a portion of the coolant flow path 40 is configured as the through holes 41 (41A, 41B) that penetrate from the outer peripheral surface 14 of the drill head (tool body) 10 to the tip surface 12 of the tip side 10t, so that it is possible to sufficiently supply coolant C to the tip side 10t of the cutting tool 1, including the amount that would have been sucked into the chip discharge holes in the conventional structure. Increasing the amount of coolant C supplied to the tip side 10t of the cutting tool 1 in this way improves the lubrication and cooling performance, particularly around the cutting edge 61, during cutting using the cutting tool 1, and ultimately improves the life of the cutting edge 61 of the cutting insert 60.

[0034] The above-described embodiment is one example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications are possible within the scope of the present invention. For example, the cutting tool 1 described in the above embodiment is a so-called indexable tool in which the cutting insert 60 can be attached and detached to the insert mounting seat 20 of the drill head (tool body) 10. However, it goes without saying that the present invention can be applied to other tools, such as the drill head (tool body) 10 itself with the cutting insert 60 removed from the cutting tool 1, or a type of tool to which a tip such as a cemented carbide alloy is brazed. [Example]

[0035] The coolant flow in the cutting tool 1 of this embodiment and a cutting tool with a conventional structure was compared by fluid analysis using simulation (see FIG. 6 ). This analysis confirmed that in the cutting tool 1 of this embodiment, the coolant C is transported through the coolant flow passage 40 and through-hole 41 to the tip side 10t of the drill head (tool body) 10, where it adequately cools and lubricates the cutting edge 61 and guide pad 80. On the other hand, in the cutting tool with a conventional structure without through-holes, the coolant is sucked into the chip discharge holes along the way, making it difficult for the coolant to reach the cutting edge. As a result, the cutting tool with the conventional structure experienced a coolant flow loss of more than 20% at the tool tip. In contrast, the cutting tool 1 of this embodiment showed a flow loss of less than 1% at the same location. [Industrial Applicability]

[0036] The present invention is suitable for application to a cutting tool for drilling holes. [Explanation of symbols]

[0037] 1...Cutting tool (for drilling holes) 10...Drill head (tool body) 10A…Center axis 10b...Base end side 10t...tip side 12…Tip surface 14...Outer surface 15...Connection 16...Large diameter section 17...Tapered section 20...Insert mounting seat 30...Chip discharge hole 31, 32...Opening of chip discharge hole 40...Coolant passage 41 (41A, 41B)...Through hole 42 (42A, 42B)...Base end opening of through hole 43 (43A, 43B)... Tip side opening of through hole 60...Cutting insert 61...Cutting edge 70...Insert mounting screw 80...Guide pad C...Coolant

Claims

1. A tool body of a cutting tool for drilling a hole, the tool body having an insert mounting seat to which a cutting insert is attached, a chip discharge hole formed from the insert mounting seat toward the base end side of the tool body, and a coolant flow path for supplying coolant from the base end side toward the tip end side of the tool body, The coolant flow path has a through hole extending from an outer peripheral surface of the tool body toward the tip end.

2. The tool body of a cutting tool for hole machining according to claim 1 , wherein the through hole penetrates through to the end face on the tip side of the tool body.

3. The tool body of a cutting tool for hole drilling according to claim 2 , wherein the through hole is branched midway.

4. 3. The tool body of a cutting tool for hole machining according to claim 2, wherein a tip-side opening of the through hole in the end face on the tip side is generally circular or elliptical with an arc, or generally trapezoidal.

5. The tool body of a cutting tool for hole drilling according to claim 1 , having a plurality of the through holes.

6. The tool body of a cutting tool for hole machining according to claim 5 , wherein the plurality of through holes are arranged in a circumferential direction along an outer circumferential surface of the tool body.

7. 7. The tool body of a cutting tool for hole machining according to claim 1, wherein the chip discharge hole is formed radially inward of the outer peripheral surface of the tool body, and a base-end opening that is an opening on the base-end side of the through hole is located closer to the base end than an opening that serves as a chip inlet on the tip-end side of the chip discharge hole.

8. The tool body of a cutting tool for hole machining according to claim 7 , wherein the chip discharge hole is made up of a plurality of holes that join together midway from the tip end side to the base end side.

9. 7. The tool body of a cutting tool for hole machining according to claim 1, comprising: a cylindrical connecting portion; and a large diameter portion formed on the tip side of the connecting portion and having a diameter larger than that of the connecting portion, wherein at least a portion of the through hole is provided to pass through the large diameter portion.

10. The tool body of a cutting tool for hole machining according to claim 9 , wherein a base end side opening of the through hole is provided in a tapered portion between the connecting portion and the large diameter portion.

11. A cutting tool for drilling holes, comprising the tool body according to any one of claims 1 to 6 and a cutting insert.

12. A cutting tool for drilling holes, a chip discharge hole formed from a tip end side to a base end side of the cutting tool; a coolant flow path that supplies coolant from a base end side to a tip end side of the cutting tool; It is equipped with The coolant flow path has a through hole extending from the outer peripheral surface of the cutting tool toward the tip end.

13. The cutting tool for hole drilling according to claim 12, which is a brazed tool having a tip brazed to the front end side.

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