Tool holder and tool unit

Abstract

To provide a technique capable of enhancing discharge efficiency of cut chips generated when processing a wall surface of a hole whose one end side is closed.SOLUTION: A tool tip portion 210a of a tool 200 is formed with a cut-out part 220 opened on a tool body part outer peripheral surface 211. The cut-out part 220 is disposed with a blade part 230 and recesses 222a, 222b for discharging cut chips. The tool 200 is held due to that a flat surface 212 is pressed with screws 140, 150 in a state that a tool shank part 210b is inserted into a body part inside space 120. A body part tip surface 110A is disposed with a coolant passage 130 which has an opening 130a and in which a coolant flows. The opening 130a of the coolant passage 130 is formed in a state that the tool 200 is held, at an opposite side to a rake face 233 of the blade part 230 along the circumferential direction of the body part tip surface 110A when viewed from one side along the axial direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technique for discharging chips generated during machining, particularly chips generated when machining the wall surface of a hole that is closed at one end. [Background technology]

[0002] A tool is sometimes used to machine the wall surface of a hole that is closed at one end. A hole that is closed at one end is a hole that does not penetrate through or has a bottom, and is called a "blind hole." For example, a tool that cuts the wall surface of a hole (called a "boring bar") is used to increase the inner diameter of the hole (called a "boring process"). When machining the wall surface of a hole that is closed at one end, a tool holder that holds the tool is attached to the tool post of a lathe. The tool holder is formed with a coolant passage through which coolant (sometimes called "lubricating oil") supplied from a coolant supply device installed on the lathe flows. Various coolants are used for lubrication, cooling, cleaning, etc. When machining the wall surface of a hole that is closed at one end, chips generated during machining may accumulate inside the hole. For this reason, it is necessary to configure the coolant passage so that the chips generated during machining are expelled from the hole by the coolant sprayed from the opening. Such a tool holder is disclosed in, for example, Patent Document 1 (JP 2015-77669 A). A tool holder 400 disclosed in Patent Document 1 has the configuration shown in Figures 5 to 7. Figure 5 is a diagram showing the tool holder 400. Figure 6 is a cross-sectional view of Figure 5 taken along line VI-VI, and Figure 7 is a cross-sectional view of Figure 5 taken along line VII-VII. FIG. 2 shows an example of a tool 200. The tool 200 has a notch 220 formed in a tool tip 210a, the notch 220 opening to a tool body outer peripheral surface 211. The notch 220 is provided with a cutting edge (called a "chip") 230 and recesses 222a and 222b (called "chip pockets") for discharging chips. The recesses 222a and 222b are formed to accommodate chips flowing from a rake face 233 of the cutting edge 230. A tool shank 210b is provided on the rear end side of the tool. A first flat surface 212 extending along the axial direction is formed on the tool body outer peripheral surface 211 of the tool shank 210b. The tool holder 400 includes a main body 410 and a tool holding means. The main body 410 is formed in a cylindrical shape extending along the axial direction, and has a main body tip surface 410A, a main body inner circumferential surface 411, and a main body inner space 420. The main body inner space 420 is formed by the main body inner circumferential surface 411, and has an opening 420a in the main body tip surface 410A. The tool 200 is held by the tool holding means with the tool shank portion 210b inserted into the main body portion inner space 420. The tool holding means includes screws 440, 450 that press against the first flat surface 212 of the tool shank portion 210b inserted into the main body portion inner space 420. The main body 410 is provided with a coolant passage 430 through which coolant supplied from a lathe (more specifically, a tool rest of the lathe) flows. The coolant passage 430 has an opening 430a formed in the main body front end surface 410A. The coolant is sprayed from the opening 430a toward the tip of the tool 200. In the conventional tool holder 400, the opening 430a of the coolant passage 430 is formed on the circumferential side of the main body front end surface 410A opposite the cutting portion 230 of the tool 200 (opposite the cutting portion 230 of the tool 200 across the main body center line P) (lower in FIG. 6 ) when viewed from one side in the axial direction with the tool 200 held in the tool holder 400. Specifically, the opening 430a is formed on the circumferential side of the main body front end surface 410A opposite the tip 234 of the cutting portion 230. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-77669 Summary of the Invention [Problem to be solved by the invention]

[0004] With the conventional tool holder 100, when using the tool 200 to machine the wall surface 311 of a hole (blind hole) 310 in a workpiece 300 that is closed at one end, the coolant is sprayed from the opening 430a of the coolant passage 430 through the opening 310a of the hole 310 into the hole 310 as shown by the arrow S in FIG. 5 . The coolant is then reflected at the back of the hole 310 and then flows out from the opening 310a of the hole 310 as shown by the arrow T. As the coolant flows through the hole 310, chips generated during machining are discharged from the hole 310. In the conventional tool holder 400, the opening 430a of the coolant passage 430 is formed on the side of the body tip surface 410A opposite the cutting portion 230 of the tool 200 across the body center line P (the side opposite the tip 233 of the cutting portion 230 along the extension direction of the rake face 233 of the cutting portion 230), when viewed from one side along the axial direction. Therefore, the coolant that has flowed into the opening 310a of the hole 310 along the path indicated by arrow S flows along the path indicated by arrow S1 and also along the path indicated by arrow S2. The path indicated by arrow S1 is the path that flows to the depths of hole 310. After the coolant flowing along the path indicated by arrow S1 is reflected at the depths of hole 310, it flows along the path indicated by arrow T. The coolant flowing along the path indicated by arrow S1 discharges chips generated during machining. On the other hand, the path indicated by arrow S2 is a path that passes through recess 222a provided in tool 200. The coolant flowing through the path indicated by arrow S2 is less effective at discharging chips. In other words, the coolant flowing through the path indicated by arrow S2 reduces the efficiency of chip discharge. The present invention has been devised in view of the above points, and aims to disclose a technique that can improve the efficiency of chip discharge. [Means for solving the problem]

[0005] The first invention relates to a tool holder for holding a tool. The tool holder of the present invention is preferably capable of holding a tool for machining the inner wall of a hole whose one end is closed. The tool extends in the axial direction and has a tool tip portion and a tool shank portion on the front and rear end sides along the axial direction. The tool tip portion has a notch portion that opens onto the outer circumferential surface of the tool. The notch portion is provided with a cutting edge portion that performs machining and a recess portion that discharges chips generated during machining using the cutting edge portion. The cutting edge portion has a cutting edge, a flank face, and a rake face. The cutting edge portion is arranged so that the rake face faces the notch portion. The shapes of the notch portion, the cutting edge portion, the recess portion, etc. can be changed as appropriate. The tool holder of the present invention comprises a body and a tool holding means. The main body extends along the axial direction and has a main body tip surface formed on the tip side along the axial direction, and a main body inner peripheral surface. The main body inner peripheral surface forms a main body internal space having an opening at the main body tip surface. The main body internal space is configured so that a tool shank of a tool can be inserted into it. The main body is also provided with a coolant passage having an opening at the main body tip surface. Coolant is preferably supplied to the coolant passage of the tool holder from the tool rest of the lathe to which the tool holder is attached. The coolant is sprayed from the opening of the coolant passage toward the tip side of the tool. The tool holding means is configured to hold a tool with the tool shank inserted into the internal space of the main body. Various known tool holding means can be used as the tool holding means. The tool holding means holds the tool with the cutting edge of the tool properly positioned relative to the tool holder. For example, a tool holding means including a screw that can abut (press against) a flat surface extending in the axial direction and formed on the outer peripheral surface of the tool shank of the tool is used. In the present invention, when the tool is held by the tool holding means, the opening of the coolant passage is formed on the tip surface of the main body, along the circumferential direction, on the opposite side from the cutting surface of the cutting edge of the tool, when viewed from one side along the axial direction. The present invention can prevent coolant sprayed from the main body from flowing into the recessed portion of the cutout of the tool, thereby improving the efficiency of removing chips generated during machining. In a different embodiment of the first aspect of the invention, the tool has a first flat surface extending along the axial direction on the side of the outer circumferential surface of the tool shank portion where the cutout portion is formed. The main body has at least one hole having an opening on the inner peripheral surface of the main body and extending along a radial direction intersecting the axial direction. The tool holding means includes at least one pressing member that is movable in at least one hole provided in the body portion along the extension direction of the hole and that is capable of pressing against a first flat surface of a tool shank portion inserted into the internal space of the body portion. Preferably, the pressing member is a screw having a male thread formed on its outer surface that can be threadedly coupled to a female thread formed on the inner surface of the hole provided in the body portion. In this case, the tool is held by pressing the first flat surface of the tool shank portion with the tip surface of the screw. In this embodiment, when a tool is held by the tool holding means, the opening of the coolant passage is formed on the tip surface of the main body, along the circumferential direction, on the opposite side to the opening of at least one hole, when viewed from one side along the axial direction. In this embodiment, the efficiency of discharging chips generated during machining can be further improved. In another embodiment of the first aspect of the present invention, the inner circumferential surface of the main body includes a first inner circumferential surface portion extending along a circle centered on the main body centerline, and a second inner circumferential surface portion connected to the first inner circumferential surface portion and extending along a curve recessed from the first inner circumferential surface portion toward the opposite side of the main body centerline. The first inner circumferential surface portion defines the main body interior space, and the second inner circumferential surface portion defines the coolant passage. In this embodiment, the coolant passage through which the coolant flows can be easily formed. In a different embodiment of the first invention, the tool has a second plane extending along the axial direction on the outer peripheral surface of the tool shank portion, opposite the first plane across the tool center line (along the circumferential direction). In this embodiment, the coolant passage is formed by the inner peripheral surface portion of the second main body portion and the second flat surface of the tool shank portion, so that the amount of coolant flowing through the coolant passage can be increased. A second invention relates to a tool unit including the above-mentioned tool and a tool holder for holding the tool. The tool unit of the present invention has the same effects as the tool holder described above. [Effects of the Invention]

[0006] By using the tool holder and tool unit of the present invention, chip removal efficiency can be improved. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 illustrates an embodiment of a tool holder. [Figure 2] FIG. 10 is a diagram illustrating an example of a tool. [Figure 3] FIG. 3 is a cross-sectional view of FIG. 1 taken along line III-III. [Figure 4] FIG. 4 is a cross-sectional view of FIG. 1 taken along line IV-IV. [Figure 5] FIG. 1 is a diagram showing a conventional tool holder. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. Fig. 1 shows a tool holder 400 according to one embodiment, an example of a tool 200 held by the tool holder 400, and an example of a workpiece 300 machined by the tool 200. Fig. 2 shows the tool 200. Fig. 3 is a cross-sectional view of Fig. 1 taken along line III-III. Fig. 4 is a cross-sectional view of Fig. 1 taken along line IV-IV. The tool holder 100 corresponds to one embodiment of the "tool holder" of the present invention. Furthermore, the combination of the tool holder 100 and the tool 200 held by the tool holder 100 corresponds to one embodiment of the "tool unit" of the present invention.

[0009] In the following description, the direction in which the center line P of the main body 110 of the tool holder 100 extends (the left-right direction in FIG. 1) is referred to as the "axial direction." The side from which the tool 200 is inserted into the main body inner space 120 of the tool holder 100 (the left side indicated by arrow A in FIG. 1) is referred to as the "tip side along the axial direction," "tip side in the axial direction," or "first axial side." The side opposite to the side from which the tool 200 is inserted into the main body inner space 120 of the tool holder 100 (the right side indicated by arrow B in FIG. 1) is referred to as the "rear side along the axial direction," "rear side in the axial direction," or "second axial side." When viewed from one side along the axial direction (see Figures 3 and 4), the direction along the circle centered on the main body center line P is called the "circumferential direction." When viewed from one side along the axial direction, the extension direction of a line passing through the main body center line P is called the radial direction. The side of the main body center line P along the radial direction is called the "radially inner side," and the side opposite the main body center line P is called the "radially outer side." With respect to the tool 200, the terms "axial direction," "circumferential direction," and "radial direction" are used in the state where the tool 200 is held by the tool holder 100. Of course, the definition of direction can be changed.

[0010] First, an example of a tool 200 that can be held by the tool holder 100 of this embodiment will be described with reference to FIG. The tool 200 includes a tool body 210 and a cutting edge (also called a "tip") 230. The tool body 210 is formed in a rod shape extending along the axial direction (extension direction of the tool center line Q), and has a tool body outer peripheral surface 211, a tool body front end surface 210A, and a tool body rear end surface 210B. The tool body outer peripheral surface 211 extends along a circle centered on the tool center line Q. The tool body outer peripheral surface 211 corresponds to the "tool outer peripheral surface" of the present invention. The tool body 210 has a tool tip portion 210a on the tip side and a tool shank portion 210b on the rear end side. The tool tip 210a has a notch 220 formed by cutting out the outer peripheral surface 211 of the tool body 210. The notch 220 is provided with a blade attachment surface 221 and recesses 222a and 222b. A cutting portion 230 is attached to the cutting portion attachment surface 221. The cutting portion 230 has cutting edges 231a and 231b, flanks 232a and 232b, and a rake face 233. The connecting portion between the cutting edges 231a and 231b is a tip 234 of the cutting portion 230. The cutting edge 230 is attached to the cutting edge attachment surface 221 so that the rake face 233 faces the notch 220 . The recesses 222a and 222b are provided to accommodate chips generated during machining using the cutting portion 230. Specifically, the recesses 222a and 222b are provided to accommodate chips that flow away from the rake face 233 of the cutting portion 230. As shown by arrow E in FIG. 2, the recess 222a extends from the rake face 233 side of the cutting portion 230 along the circumferential direction toward the opposite side to the tip 234 of the cutting portion 230 and toward the rear end along the axial direction. As shown by arrow F in FIG. 2, the recess 222b extends from the rake face 233 side of the cutting portion 230 toward the rear end along the axial direction. A first flat surface 212 extending along the axial direction is formed on the outer peripheral surface 211 of the tool body of the tool shank portion 210b at a position corresponding to the cutout portion 220. Furthermore, a second flat surface 213 extending along the axial direction is formed on the outer peripheral surface 211 of the tool body of the tool shank portion 210b along the circumferential direction (across the tool center line Q) on the opposite side to the first flat surface 212.

[0011] Next, an example of the workpiece 300 will be described. The workpiece 300 has a hole (blind hole) 310 that is closed at one end (front end) and open at the other end (rear end). The hole 310 is formed by a wall surface 311. The tool 200 processes the wall surface 311 of the hole 310 .

[0012] Next, the tool holder 100 of this embodiment will be described. The tool holder 100 comprises a body 110 and a tool holding means. The main body 110 is formed in a cylindrical shape extending along the axial direction. The main body 110 has a main body front end surface 110A, a main body rear end surface 110B, a main body inner circumferential surface 111, and a main body outer circumferential surface 112. The main body inner circumferential surface 111 forms a main body inner space 120 having an opening 120a at the main body front end surface 110A and an opening 120b at the main body rear end surface 110B. As shown in Fig. 4, the main body 110 has a hole 115 formed therein, which extends in a radial direction intersecting the axial direction and opens to the main body inner circumferential surface 111. In Fig. 4, the hole 115 has an opening 115a in the main body inner circumferential surface 111 and an opening 115b in the main body outer circumferential surface 112. A female thread is formed in the wall surface 114 of the hole 115. A screw 140 constituting the tool holding means is inserted into the hole 115. Although not shown, a hole 116 similar to the hole 115 is also formed therein. A screw 150 constituting the tool holding means is inserted into the hole 116.

[0013] The tool holding means includes screws 140 and 150. An external thread is formed on the outer peripheral surface of screw 140 so that it can be threadedly coupled to an internal thread formed on wall surface 114 of hole 115. In addition, an external thread is formed on the outer peripheral surface of screw 150 so that it can be threadedly coupled to an internal thread formed on wall surface 114 of hole 116. When holding the tool 200 , the tool shank portion 210 b is inserted into the main body portion inner space 120 so that the first flat surface 212 faces the opening 115 a of the hole 115 . Then, the screw 140 is protruded into the body inner space 120 along the extension direction of the hole 115, and the tip of the screw 140 is brought into contact with the first flat surface 212 of the tool shank portion 210b. By adjusting the position of the screw 140 in the radial direction, the tool 200 is held in the tool holder 100. Similarly, the tip of the screw 150 is brought into contact with the first flat surface 212 of the tool shank portion 210b. In this embodiment, holes 115 and 116 correspond to "at least one hole having an opening on the inner peripheral surface of the main body and extending in a radial direction intersecting the axial direction" of the present invention. Also, screws 140 and 150 correspond to "at least one pressing member movable in the at least one hole along the extending direction of the hole and capable of pressing against a first flat surface of a tool shank inserted into the internal space of the main body" of the present invention.

[0014] In this embodiment, the main body inner circumferential surface 111 includes a first main body inner circumferential surface portion 111a and a second main body inner circumferential surface portion 111b, as shown in FIG. The first main body inner circumferential surface portion 111a extends along a circle centered on the main body center line P. The second main body inner circumferential surface portion 111b is connected to the first main body inner circumferential surface portion 111a and extends from the first main body inner circumferential surface portion 111a along a curve that is recessed in the opposite direction (radially outward) from the main body center line P. The first main body inner peripheral surface portion 111a forms the main body inner space 120. The second main body inner peripheral surface portion 111b forms the coolant passage 130. The coolant passage 130 opens to the main body front end surface 110A, the main body rear end surface 110B, and the main body inner space 120.

[0015] When machining the wall surface 311 of the hole 310 in the workpiece 300 using the tool 200, the tool holder 100 holding the tool 200 is attached to the tool rest of the lathe. That is, with the tool shank portion 210b inserted into the main body internal space 120, the tool 200 is held in the tool holder 100 by the tool holding means. In this embodiment, the screw 140 (150) constituting the tool holding means is moved along the extending direction of the hole 115 (116) to protrude into the main body internal space 120. As a result, the tip of the screw 140 (150) comes into contact with the first flat surface 212 of the tool shank portion 210b, pressing against the tool shank portion 210b. At this time, the second main body inner surface portion 111b and the second flat surface 213 of the tool shank portion 210b form a coolant passage 130 (openings 130a, 130b) that opens to the main body tip surface 110A and the main body rear end surface 110B. When machining is performed using the tool 200, coolant is supplied from a lathe (more specifically, a tool rest of the lathe) to the coolant passage 130 through the opening 130b. The coolant that flows through the coolant passage 130 is sprayed toward the tip of the tool 200 from the opening 130a formed in the main body tip surface 110A. In this embodiment, as shown in Fig. 3, when viewed from one side along the axial direction, the opening 130a of the coolant passage 130 is formed on the opposite side of the rake face 233 of the cutting portion 230 of the tool 200 along the circumferential direction when the tool 200 is held by the tool holder 100. Alternatively, when viewed from one side along the axial direction, the opening 130a is formed on the opposite side of the notch portion 220 of the tool 200 along the circumferential direction (across the center line P of the main body). Alternatively, as shown in Fig. 4, when viewed from one side along the axial direction, the opening 130a is formed on the opposite side of the first flat surface 212 of the tool shank portion 210b (where the screws 140, 150 constituting the tool holding means abut) along the circumferential direction (across the center line P of the main body) when the tool 200 is held by the tool holder 100. As a result, the coolant sprayed from opening 130a flows from opening 310a of hole 310 in workpiece 300 into hole 310 along the path indicated by arrow M in Fig. 1. After being reflected at the back of hole 310, the coolant flows out of opening 310a of hole 310 via the path indicated by arrow N (including the path from rake face 233 to recess 222a and the path from rake face 233 to recess 222b). In this embodiment, the path indicated by arrow M passes along the circumferential direction on the side opposite to the rake face 233 (opposite to the recess 222a). This prevents the coolant from flowing into the recess 222a before reaching the depths of the hole 310, as occurs in the conventional tool holder 400. In other words, the amount of coolant flowing along the path indicated by arrow M and the path indicated by arrow N can be increased. This allows the coolant to efficiently discharge chips generated during machining by the tool 200. In other words, the efficiency of discharging chips can be improved.

[0016] The present invention is not limited to the configurations described in the embodiments, and various modifications, additions, and deletions are possible. In the embodiment, the coolant passage is formed by a part of the inner circumferential surface of the main body, but the method of forming the coolant passage is not limited to this. Although the tool holding means used herein includes a screw that abuts against the flat surface of the tool shank, various known tool holding means can be used. Although the main body inner space is provided so as to be open to the front end surface and rear end surface of the main body, it is sufficient that the main body inner space is open to at least the front end surface of the main body. In the embodiment, a tool (boring bar) that cuts the wall surface to increase the inner diameter of the hole is used as a tool for processing the wall surface of a hole that is closed at one end, but the tool for processing the wall surface of a hole that is closed at one end is not limited to this. In the embodiment, the tool holder of the present invention is described as holding a tool for machining the wall surface of a hole whose one end is closed, but the tool holder of the present invention can be configured as a tool holder for holding tools of various configurations. Each of the configurations described in the embodiments can be used alone, or a plurality of appropriately selected configurations can be used in combination. [Explanation of symbols]

[0017] 100, 400 tool holder 110, 410 Main body 110A, 410A Main body tip surface 110B, 410B Main body rear end surface 111, 411 Inner surface of main body 111a, 111b, 411a, 411b Inner peripheral surface of main body 112, 412 Outer surface of main body 114, 414 Hole wall 115, 415 holes 115a, 115b, 415a, 415b opening 120, 420 Main body inner space 120a, 120b, 420a, 420b opening 130, 430 coolant passages 130a, 130b, 430a, 430b opening 140, 150, 440, 450 screws 200 Tools 210 Tool body 210A Tool body tip surface 210B Rear end surface of tool body 210a Tool tip 210b Tool shank 211 Tool body outer circumferential surface 212, 213 plane 220 Notch 221 Blade attachment surface 222a, 222b recesses 230 Blade part 231a, 231b blade 232a, 232b flank 233 Rake face 234 Tip 300 Work 310 holes 310a opening 311 Wall

Claims

1. A tool holder for holding a tool having a tool tip portion and a tool shank portion on a front end side and a rear end side along an axial direction, wherein a cutout portion that opens to an outer peripheral surface of the tool is formed in the tool tip portion, and a cutting portion and a recessed portion for discharging chips are provided in the cutout portion, A tool holder includes a main body and a tool holding means. the main body extends along the axial direction and includes a main body tip surface, a main body inner peripheral surface, a main body inner space formed by the main body inner peripheral surface and having an opening at the main body tip surface and into which the tool shank of the tool can be inserted, and a coolant passage having an opening at the main body tip surface and through which coolant can be sprayed, the tool holding means is configured to be able to hold the tool with the tool shank portion inserted into the body portion internal space, the opening of the coolant passage is formed on the tip surface of the main body along the circumferential direction, on a side opposite to the rake face of the cutting edge, as viewed from one side along the axial direction when the tool is held by the tool holding means.

2. 2. The tool holder according to claim 1, the tool has a first flat surface extending along the axial direction on a side of the tool outer peripheral surface of the tool shank portion where the cutout portion is formed, the main body portion has an opening on an inner circumferential surface of the main body portion and includes at least one hole extending along a radial direction intersecting the axial direction, the tool holding means includes at least one pressing member that is movable in the at least one hole along an extension direction of the hole and that is capable of pressing the first flat surface of the tool shank portion inserted into the body portion internal space, the opening of the coolant passage is formed on the tip surface of the main body along the circumferential direction on an opposite side to the opening of the at least one hole when viewed from one side along the axial direction in a state in which the tool is held by the tool holding means.

3. 3. The tool holder according to claim 2, the main body inner circumferential surface includes a first main body inner circumferential surface portion extending along a circle centered on the main body center line, and a second main body inner circumferential surface portion connected to the first main body inner circumferential surface portion and recessed from the first main body inner circumferential surface portion toward the opposite side of the main body center line, the first main body inner circumferential surface portion defining the main body inner space, and the second main body inner circumferential surface portion defining the coolant passage.

4. 4. The tool holder according to claim 3, the tool has a second flat surface on the outer peripheral surface of the tool shank portion, the second flat surface extending along the axial direction on the opposite side of the tool center line from the first flat surface.

5. A tool unit including a tool and a tool holder for holding the tool, the tool has a tool tip portion and a tool shank portion on the front and rear end sides along the axial direction, the tool tip portion has a notch portion that opens to the outer peripheral surface of the tool, and the notch portion has a cutting edge portion and a recess portion for discharging chips, the tool holder comprises a body and a tool holding means; the main body extends along the axial direction and includes a main body tip surface, a main body inner peripheral surface, a main body inner space formed by the main body inner peripheral surface and having an opening at the main body tip surface and into which the tool shank of the tool can be inserted, and a coolant passage having an opening at the main body tip surface and through which coolant can be sprayed, the tool holding means is configured to be able to hold the tool with the tool shank portion inserted into the body portion internal space, the opening of the coolant passage is formed on the tip surface of the main body along the circumferential direction, on a side opposite to the rake face of the cutting edge, as viewed from one side along the axial direction when the tool is held by the tool holding means.

Images