Tool holder and indexable cutting tool

Abstract

To provide a tool holder having a rotation preventing mechanism capable of improving manufacturability, durability and replaceability when a small-diameter round piece insert is applied, and a cutting edge replaceable cutting tool.SOLUTION: A tool holder 1 to which a disk-shaped cutting insert 2 having a diameter size of a rake face 21 of less than 8 mm is detachably attached includes a holder body 11, a fastening member 12, and a rotation prevention member 13 detachably attached to the holder body 11, the holder body 11 has a through hole 17 opening to a bottom surface 15b of an insert pocket 15, and the insert pocket 15 has a second support surface 15e in contact with a seating surface 22 of the cutting insert 2. The through hole 17 is arranged side by side with the second support surface 15e, the anti-rotation member 13 has an insertion portion 13a inserted into the through hole 17 and a protruding portion 13b protruding from the through hole 17, and the protruding portion 13b comes into contact with the restraint surface 26, thereby regulating the rotation of the insert 2.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a tool holder for a small diameter round insert and an indexable cutting tool. [Background technology]

[0002] Conventionally, indexable cutting tools have been known that include a disk-shaped cutting insert and a tool holder to which the cutting insert is detachably attached (for example, Patent Documents 1 and 2). Herein, the cutting insert may be referred to as a round insert or an insert, and the indexable cutting tool may be referred to as a cutting tool or a tool, etc.

[0003] In this type of indexable cutting tool, a shape with a protrusion that cooperates with a restraining surface on the side of the insert has been provided for the purpose of preventing rotation of the insert. Specifically, in Patent Document 1, the insert fixing portion of the tool body (tool holder) is provided with a rotation prevention portion that abuts against the rotation prevention surface of the insert. Also, in Patent Document 2, the rotation prevention surface of the circular insert contacts a rotation prevention member of the tool body, and the rotation prevention member is incorporated into the tool body and fixed to the tool body by a fixing member.

[0004] Patent Documents 1 and 2 disclose cutting tools in which a round insert with an inscribed circle dimension (diameter dimension of the rake face) of 8 to 16 mm is attached to a tool body with a cutting edge diameter (tool diameter) of about 50 mm. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5648738 [Patent Document 2] Patent No. 5110400 Summary of the Invention [Problem to be solved by the invention]

[0006] For example, when cutting narrow grooves or pockets in a workpiece, a smaller insert with a rake face diameter of less than 8 mm is required (in this specification, such small inserts may be referred to as small diameter round inserts). However, as a result of extensive research, the inventors of the present invention have found that applying the insert rotation prevention mechanisms described in Patent Documents 1 and 2 to small diameter round inserts as is results in the following problems.

[0007] (Manufacturability issues) When the insert size is reduced, each part of the tool holder also becomes smaller. Naturally, the protrusions of the anti-rotation parts or anti-rotation members that contact the anti-rotation surface (restraint surface) of the insert also become smaller, making their manufacture difficult and requiring increased worker skill, increased manufacturing time, and in some cases the introduction of specialized equipment. In other words, manufacturing issues have arisen that were not particularly problematic with conventional medium- to large-sized inserts (medium-diameter round inserts and large-diameter round inserts) with a rake face diameter of 8 mm or more.

[0008] (Durability issue) Furthermore, the small protrusions used in small diameter round inserts are susceptible to impacts during cutting, which can lead to chipping and warping. Therefore, the protrusions described in Patent Documents 1 and 2 have room for improvement in durability.

[0009] (The issue of commutativity) Furthermore, in a structure in which the tool holder and the protrusion are integrated as described in Patent Document 1, if the protrusion is damaged, the tool holder itself needs to be replaced, which is costly and uneconomical. On the other hand, in a structure in which the tool holder and the protrusion are separate, as described in Patent Document 2, it is possible to replace only the protrusion. However, since this structure involves fixing the protrusion (rotation prevention member) by tightening a fixing member after the protrusion is incorporated into the tool holder, there is room for improvement in the positioning of the protrusion.

[0010] An object of the present invention is to provide a tool holder and an indexable cutting tool equipped with an anti-rotation mechanism that can improve manufacturability, durability, and replaceability when using small diameter round inserts. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention provides the following means.

[0012] [Aspect 1 of the present invention] a holder body having an insert pocket into which the cutting insert is attached and a through hole opening at a bottom surface of the insert pocket, the insert pocket having one or more first support surfaces arranged on a side surface of the insert pocket and contacting the outer peripheral surface of the cutting insert, and a second support surface arranged on the bottom surface of the insert pocket and contacting the seating surface of the cutting insert, the through hole being arranged side by side with the second support surface, the rotation prevention member having an insertion portion inserted into the through hole and a protrusion protruding from the through hole, the protrusion coming into contact with the constraining surface restricting rotation of the cutting insert about the insert central axis.

[0013] [Aspect 2 of the present invention] The tool holder of aspect 1, wherein the through hole has a first hole portion that opens to a bottom surface of the insert pocket and a second hole portion that is located on the opposite side of the through hole from the bottom surface of the first hole portion, and the inner diameter dimension of the first hole portion is larger than the inner diameter dimension of the second hole portion.

[0014] [Embodiment 3 of the present invention] The tool holder according to aspect 1 or 2, wherein the anti-rotation member is cylindrical or columnar, and where L1 is the amount of protrusion of the protrusion from the through hole, 0.08 mm≦L1≦0.25 mm.

[0015] [Aspect 4 of the present invention] An indexable cutting tool comprising: a disc-shaped cutting insert having a rake face with a diameter dimension of less than 8 mm; and a tool holder to which the cutting insert is detachably attached, wherein the cutting insert is provided with a restraining surface that is disposed on an outer peripheral surface of the cutting insert and reaches a seating surface of the cutting insert; the tool holder comprises a holder body, a fastening member that fixes the cutting insert to the holder body, and a rotation prevention member that is detachably attached to the holder body and comes into contact with the restraining surface; and the holder body comprises an insert pocket to which the cutting insert is attached, and a fastening member that fastens the insert to the holder body. a through hole opening to a bottom surface of the insert pocket, the insert pocket having one or more first support surfaces arranged on a side surface of the insert pocket and contacting an outer peripheral surface of the cutting insert, and a second support surface arranged on the bottom surface of the insert pocket and contacting a seating surface of the cutting insert, the through hole being arranged alongside the second support surfaces, the anti-rotation member having an insertion portion inserted into the through hole and a protrusion protruding from the through hole, and the protrusion coming into contact with the restraint surface restricts rotation of the cutting insert around the insert central axis.

[0016] [Embodiment 5 of the present invention] A replaceable cutting tool as described in aspect 4, wherein the through hole has a first hole portion that opens to the bottom surface of the insert pocket and a second hole portion that is located on the opposite side of the through hole from the bottom surface of the first hole portion, and the inner diameter dimension of the first hole portion is larger than the inner diameter dimension of the second hole portion.

[0017] [Aspect 6 of the present invention] 6. The indexable cutting tool according to claim 4 or 5, wherein the anti-rotation member is cylindrical or columnar, and the protrusion amount that the protrusion protrudes from the through hole is L1, and the relationship is 0.08 mm≦L1≦0.25 mm. [Effects of the Invention]

[0018] According to the above aspects of the present invention, there are provided a tool holder and an indexable cutting tool equipped with an anti-rotation mechanism that can improve manufacturability, durability, and replaceability when using small diameter round inserts. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is an exploded perspective view showing an indexable cutting tool according to the present embodiment. [Figure 2] FIG. 2 is an enlarged perspective view of a portion II in FIG. [Figure 3] FIG. 3 is a side view showing a part of the indexable cutting tool of this embodiment. [Figure 4] FIG. 4 is a cross-sectional view showing the IV-IV cross section of FIG. [Figure 5] FIG. 5(a) is a top view showing the cutting insert, FIG. 5(b) is a side view showing the cutting insert, and FIG. 5(c) is a bottom view showing the cutting insert. [Figure 6] 6 is a side view of the cutting insert and the anti-rotation member as seen from the direction of arrow VI in FIG. [Figure 7] 7 is a bottom view of the cutting insert and the anti-rotation member as seen from the direction of arrow VII in FIG. 6. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] A tool holder 1 and an indexable cutting tool 10 according to one embodiment of the present invention will be described with reference to the drawings. The indexable cutting tool 10 of this embodiment is a milling tool such as a small-diameter indexable end mill having a cutting edge diameter (tool diameter) of 8 mm to 16 mm.

[0021] 1, 3, and 4, an indexable cutting tool 10 includes a disk-shaped cutting insert 2 and a tool holder 1 to which the cutting insert 2 is removably attached. The tool holder 1 also includes a holder body 11 centered on the tool central axis O1, a fastening member 12 that fixes the cutting insert 2 to the holder body 11, and an anti-rotation member 13 that is removably attached to the holder body 11.

[0022] Here, the definition of the directions used in this embodiment will be described. In this embodiment, the direction in which the tool center axis O1, which is the central axis of the holder body 11, extends, i.e., the direction along the tool center axis O1, is referred to as the tool axis direction. As shown in FIG. 1 , the cutting insert 2 is disposed at the first end 11a of both end portions (first end 11a and second end 11b) of the holder body 11 in the tool axis direction. In this embodiment, the direction from the first end 11a, where the cutting insert 2 is disposed, to the second end 11b in the tool axis direction is referred to as the rear end side or simply the rear end side in the tool axis direction. Furthermore, the direction from the second end 11b to the first end 11a in the tool axis direction is referred to as the front end side or simply the front end side in the tool axis direction. Therefore, the first end 11a corresponds to the front end portion 11a of the holder body 11, and the second end 11b corresponds to the rear end portion 11b of the holder body 11.

[0023] The direction perpendicular to the tool center axis O1 is called the tool radial direction. Within the tool radial direction, the direction approaching the tool center axis O1 is called the inner tool radial direction, and the direction away from the tool center axis O1 is called the outer tool radial direction.

[0024] The direction around the tool center axis O1 is called the tool circumferential direction. Within the tool circumferential direction, the direction in which the indexable cutting tool 10 is rotated during cutting is called the tool rotation direction T, and the opposite rotation direction is called the opposite side of the tool rotation direction T or the counter-tool rotation direction.

[0025] 5(a) to 5(c), the cutting insert 2 has a disk shape centered on an insert central axis O4. In this embodiment, the direction in which the insert central axis O4, which is the central axis of the cutting insert 2, extends, i.e., the direction along the insert central axis O4, is referred to as the insert axial direction or the up-down direction.

[0026] 4 to 7, the insert axial direction (vertical direction) corresponds to the Z-axis direction. In the Z-axis direction, the +Z side is referred to as one side or upper side of the insert axial direction, and the -Z side is referred to as the other side or lower side of the insert axial direction. The insert axial direction (vertical direction) can also be referred to as the plate thickness direction of the cutting insert 2.

[0027] 5(a) to 5(c), the cutting insert 2 has a pair of plate surfaces 21, 22 facing opposite to each other in the insert axial direction (Z-axis direction). Of the pair of plate surfaces 21, 22, the plate surface 21 facing one side in the insert axial direction (upper side, +Z side) is the upper surface 21, and the other plate surface 22 facing the other side in the insert axial direction (lower side, -Z side) is the lower surface 22. In this embodiment, the upper surface 21 of the cutting insert 2 is called the rake surface 21, and the lower surface 22 is called the seating surface 22.

[0028] The direction perpendicular to the insert central axis O4 is referred to as the insert radial direction. Within the insert radial direction, the direction approaching the insert central axis O4 is referred to as the insert radial inner direction, and the direction away from the insert central axis O4 is referred to as the insert radial outer direction.

[0029] Furthermore, the direction circumferentially around the insert central axis O4 is referred to as the insert circumferential direction. Within the insert circumferential direction, a predetermined rotational direction is referred to as one side of the insert circumferential direction θ1, and the opposite rotational direction is referred to as the other side of the insert circumferential direction θ2. In this embodiment, as shown in FIG. 5(a), when viewing the cutting insert 2 from one side (+Z side) in the insert axial direction (i.e., from a top view with the cutting face 21 facing forward), the clockwise rotational direction around the insert central axis O4 corresponds to one side of the insert circumferential direction θ1, and the counterclockwise rotational direction corresponds to the other side of the insert circumferential direction θ2. In addition, definitions of directions other than those mentioned above will be explained separately as appropriate, if necessary.

[0030] Each of the components of the indexable cutting tool 10 will now be described in detail. The cutting insert 2 is formed of a hard sintered body, for example, made of cemented carbide. As shown in FIGS. 1 and 3, a plurality of cutting inserts 2 are provided in an indexable cutting tool 10. The plurality of cutting inserts 2 are arranged at intervals from one another in the circumferential direction of the tool on the outer periphery of the tip of the holder body 11. In this embodiment, three cutting inserts 2 are provided at equal intervals in the circumferential direction of the tool. Although not specifically shown, the insert center axis O4 of each cutting insert 2 extends in the direction of a tangent to an imaginary circle centered on the tool center axis O1.

[0031] As shown in Figures 4 and 5(a) to (c), the cutting insert 2 has a cutting surface 21, a seating surface 22, an outer peripheral surface 23 connected to the cutting surface 21 and the seating surface 22, a cutting edge 24 arranged on the ridge portion where the cutting surface 21 and the outer peripheral surface 23 are connected, a screw insertion hole 25 passing through the cutting insert 2 in the insert axial direction (up and down direction), and a restraint surface 26 arranged on the outer peripheral surface 23.

[0032] The rake face 21 has a circular surface shape. More specifically, the rake face 21 is a circular annular plane centered on the insert central axis O4 and extends in a direction perpendicular to the insert central axis O4. The diameter dimension (outer diameter dimension) of the rake face 21 is less than 8 mm. Accordingly, the diameter dimension (outer diameter dimension) of the cutting insert 2 is also less than 8 mm. Therefore, the cutting insert 2 of this embodiment may be rephrased as a small diameter round insert 2. The diameter dimension of the rake face 21 is, for example, 4 mm or more. The diameter dimension of the cutting insert 2 is also, for example, 4 mm or more.

[0033] The seating surface 22 has a substantially circular surface shape. More specifically, the seating surface 22 is a substantially circular annular plane centered on the insert central axis O4 and extends in a direction perpendicular to the insert central axis O4. The diameter (outer diameter) of the seating surface 22 is smaller than the diameter of the rake face 21.

[0034] The outer peripheral surface 23 has an upper end connected to the outer peripheral portion (cutting edge 24) of the rake face 21, and a lower end connected to the outer peripheral portion of the seating surface 22. The outer peripheral surface 23 has a tapered surface shape that decreases in diameter as it extends downward (to the -Z side) from the cutting edge 24. The outer peripheral surface 23 may also be referred to as a flank surface 23. The cutting edge 24 has a circular shape centered on the insert central axis O4.

[0035] The screw insertion hole 25 extends inside the cutting insert 2 in the insert axial direction (up and down direction), and opens to the rake face 21 and the seating surface 22. The screw insertion hole 25 has a large diameter hole portion 25a that opens to the rake face 21, a small diameter hole portion 25b that opens to the seating surface 22, and a tapered hole portion 25c that is disposed between the large diameter hole portion 25a and the small diameter hole portion 25b in the insert axial direction.

[0036] The large diameter hole portion 25a is a substantially circular hole centered on the insert central axis O4. The small diameter hole portion 25b is a circular hole centered on the insert central axis O4. The inner diameter of the large diameter hole portion 25a is larger than the inner diameter of the small diameter hole portion 25b.

[0037] The tapered hole portion 25c has a tapered hole shape centered on the insert central axis O4, and the inner diameter dimension decreases (constricts) toward the lower side (-Z side). The upper end of the tapered hole portion 25c is connected to the lower end of the large diameter hole portion 25a. The lower end of the tapered hole portion 25c is connected to the upper end of the small diameter hole portion 25b.

[0038] The constraint surface 26 is disposed at least at the lower end of the outer peripheral surface 23, and in this embodiment, is disposed in approximately the lower half of the outer peripheral surface 23. The constraint surface 26 is recessed from the outer peripheral surface 23. Specifically, the constraint surface 26 is formed to be recessed more inward in the insert radial direction than the portion of the outer peripheral surface 23 other than the constraint surface 26. The constraint surface 26 also reaches the seating surface 22. That is, the constraint surface 26 is open not only to the outer peripheral surface 23 but also to the seating surface 22.

[0039] The restraining surface 26 has a curved surface that is concave toward the inside in the insert radial direction. In a cross-sectional view (transverse cross-section) perpendicular to the insert center axis O4, the restraining surface 26 has a concave curved shape that is recessed toward the inside in the insert radial direction (see FIG. 5(c)). Note that the "curve" of the concave curved shape here refers to a shape that does not have a straight line with a length of 0.05 mm or more in the cross-sectional view or in a bottom view of the seating surface 22 viewed from the front as shown in FIG. 5(c).

[0040] 5(b), in a side view of the cutting insert 2 seen from the outside in the insert radial direction, the restraining surface 26 has a generally semicircular shape that is convex upward (toward the +Z side). The maximum dimension (maximum width dimension) W of the restraining surface 26 in the insert circumferential direction is greater than the maximum dimension (maximum height dimension) L2 of the restraining surface 26 in the insert axial direction. In this embodiment, the maximum dimension L2 of the restraining surface 26 in the insert axial direction is set to be equal to or less than half of the overall length dimension (total height dimension) of the cutting insert 2 in the insert axial direction.

[0041] The circumferential dimension (width dimension) of the restraint surface 26 is approximately constant along the insert axial direction near the lower end connected to the seating surface 22, and in the portion located above this lower end (on the +Z side), it gradually becomes smaller as it moves upward.

[0042] As shown in FIG. 5(c), a plurality of constraint surfaces 26 are provided on the cutting insert 2. The plurality of constraint surfaces 26 are arranged on the outer peripheral surface 23 at intervals in the insert circumferential direction. In this embodiment, six constraint surfaces 26 are provided at equal intervals in the insert circumferential direction. Therefore, the cutting insert 2 can be indexed six times around the insert central axis O4. In other words, the cutting insert 2 can change the position of the cutting edge 24 in the insert circumferential direction six times.

[0043] The holder body 11 is made of, for example, steel. As shown in FIG. 1 , the holder body 11 has a columnar shape centered on the tool central axis O1, and in this embodiment, it has a substantially multi-stage cylindrical shape. The holder body 11 extends in the tool axial direction. A rear end portion 11b of the holder body 11 is detachably attached to a spindle or the like of a machine tool (not shown). The indexable cutting tool 10 performs a predetermined cutting process by causing the cutting edge 24 of the cutting insert 2 to cut into a workpiece by rotating the holder body 11 in the tool rotation direction T by the spindle or the like of the machine tool and moving it in the tool radial direction and the tool axial direction.

[0044] The holder body 11 has a concave chip pocket 14 that opens to the tip surface and outer peripheral surface of the holder body 11, a concave insert pocket 15 that is recessed in the counter-tool rotation direction from a wall surface 14a of the chip pocket 14 facing the tool rotation direction T, an insert support portion 16 that is arranged adjacent to the insert pocket 15 in the counter-tool rotation direction, a screw hole 18 that opens to a bottom surface 15b of the insert pocket 15 that will be described later, and a through hole 17 that opens to the bottom surface 15b.

[0045] The number of sets of chip pockets 14, insert pockets 15, insert supports 16, through holes 17, and screw holes 18 provided in the holder body 11 is the same as the number of cutting inserts 2 provided in this cutting tool. In this embodiment, the number of sets is plural, specifically, three sets.

[0046] The chip pocket 14 is arranged on the outer periphery of the tip of the holder body 11. The chip pocket 14 is recessed from the tip surface of the holder body 11 toward the rear end in the tool axial direction, and is also recessed from the outer periphery of the holder body 11 inward in the tool radial direction. The chip pocket 14 is arranged adjacent to the insert pocket 15 in the tool rotation direction T of the insert pocket 15. A plurality of chip pockets 14 are provided in the holder body 11. The plurality of chip pockets 14 are arranged on the outer periphery of the tip of the holder body 11 at intervals from one another in the tool circumferential direction.

[0047] The insert pocket 15 is arranged on the outer periphery of the tip of the holder body 11. The insert pocket 15 is also located on the outer periphery of the tip of the wall surface 14a of the chip pocket 14 that faces the tool rotation direction T. The insert pocket 15 is recessed from the tip surface of the holder body 11 toward the rear end in the tool axial direction, and is also recessed from the outer periphery of the holder body 11 inward in the tool radial direction. A plurality of insert pockets 15 are provided in the holder body 11. The multiple insert pockets 15 are arranged on the outer periphery of the tip of the holder body 11 at intervals from each other in the tool circumferential direction.

[0048] The cutting insert 2 is removably attached to the insert pocket 15. Note that the cutting edge diameter (tool diameter) in this embodiment refers to the maximum diameter dimension of the rotation trajectory of the cutting edge 24 obtained by rotating the cutting insert 2 attached to the insert pocket 15 around the tool central axis O1.

[0049] 3 and 4, when the cutting insert 2 is attached to the insert pocket 15, the screw hole central axis O2, which is the central axis of the screw hole 18, and the insert central axis O4 are slightly offset from each other and extend parallel to each other. More specifically, the insert central axis O4 is located slightly toward the tip side in the tool axial direction and slightly outward in the tool radial direction than the screw hole central axis O2.

[0050] The direction in which the screw hole central axis O2 extends (the screw hole axial direction) is the same as the insert axial direction and the up-down direction (the Z axis direction). One side of the screw hole axial direction corresponds to the +Z side, and the other side of the screw hole axial direction corresponds to the -Z side.

[0051] In this embodiment, the direction perpendicular to the screw hole central axis O2 is referred to as the screw hole radial direction. Of the screw hole radial directions, the direction approaching the screw hole central axis O2 is referred to as the inner screw hole radial direction, and the direction away from the screw hole central axis O2 is referred to as the outer screw hole radial direction. The screw hole radial direction roughly corresponds to the insert radial direction.

[0052] The direction around the central axis O2 of the screw hole is called the circumferential direction of the screw hole. The circumferential direction of the screw hole roughly corresponds to the circumferential direction of the insert.

[0053] The screw hole central axis O2 corresponds to the central axis of the insert pocket 15, and may therefore be referred to as the pocket central axis O2. In this case, the screw hole axial direction may be referred to as the pocket axial direction. The screw hole radial direction may be referred to as the pocket radial direction. The screw hole circumferential direction may be referred to as the pocket circumferential direction.

[0054] As shown in Figure 2, the insert pocket 15 has a side surface 15a facing the tip side in the tool axial direction and outward in the tool radial direction, and a bottom surface 15b facing in the tool rotation direction T. The side surface 15a is a wall surface facing inward in the screw hole radial direction, and the bottom surface 15b is a wall surface facing one side (+Z side) in the screw hole axial direction. The side surface 15a is a generally concave curved surface extending in the screw hole circumferential direction. The bottom surface 15b is a flat surface extending in a direction perpendicular to the screw hole central axis O2.

[0055] The insert pocket 15 also has one or more first support surfaces 15c arranged on the side surface 15a and in contact with the outer peripheral surface 23 of the cutting insert 2, a concave recessed portion 15d recessed from the side surface 15a, and a second support surface 15e arranged on the bottom surface 15b and in contact with the seating surface 22 of the cutting insert 2.

[0056] The first support surface 15c faces inward in the screw hole radial direction and has a concave curved surface extending in the screw hole circumferential direction. The first support surface 15c is positioned outward in the screw hole radial direction as it moves toward one side (the +Z side) in the screw hole axial direction. Although not particularly shown, in a cross-sectional view that passes through a portion of the first support surface 15c and includes the screw hole central axis O2 within the plane, the angle formed between the first support surface 15c and the bottom surface 15b (second support surface 15e) is an obtuse angle greater than 90°.

[0057] In this embodiment, two first support surfaces 15c are provided in the insert pocket 15. The two first support surfaces 15c are arranged at an interval from each other in the circumferential direction of the screw hole. Of the two first support surfaces 15c, one first support surface 15c is arranged inward in the tool radial direction from the screw hole central axis O2 and faces outward in the tool radial direction. Of the two first support surfaces 15c, the other first support surface 15c is arranged closer to the rear end in the tool axial direction from the screw hole central axis O2 and faces toward the front end in the tool axial direction.

[0058] Each first support surface 15c contacts a portion of the outer peripheral surface 23 of the cutting insert 2 other than the constraint surface 26. Each first support surface 15c contacts a part of the outer peripheral surface 23 in the insert circumferential direction, more specifically, contacts at least a portion of the outer peripheral surface 23 located above (on the +Z side of) the constraint surface 26. The portion of the outer peripheral surface 23 that the first support surface 15c contacts may also be referred to as a flank-side constraint surface or a supported surface.

[0059] The recess 15d is recessed from the side surface 15a outward in the radial direction of the screw hole. The recess 15d is located at the inner end of the insert pocket 15 in the radial direction of the tool and at the rear end in the axial direction of the tool. The recess 15d is disposed between the two first support surfaces 15c in the circumferential direction of the screw hole. In other words, the two first support surfaces 15c are separated from each other by the recess 15d.

[0060] The recessed portion 15d has a side wall and a bottom wall. The side wall of the recessed portion 15d has a concave curved surface that is recessed outward in the screw hole radial direction from the side surface 15a of the insert pocket 15. When the insert pocket 15 is viewed from one side (+Z side) in the screw hole axial direction, the side wall of the recessed portion 15d has a curved surface that is concave outward in the screw hole radial direction (see FIG. 3).

[0061] 2, the bottom wall of the recess 15d is flat and extends in a direction perpendicular to the screw hole central axis O2. The bottom wall of the recess 15d forms part of the bottom surface 15b of the insert pocket 15. In other words, by providing the recess 15d, the bottom surface 15b of the insert pocket 15 has a substantially semicircular region 15f that is located outward of the two first support surfaces 15c in the screw hole radial direction.

[0062] The second support surface 15e has a circular surface shape and faces one side (+Z side) in the screw hole axial direction. Specifically, the second support surface 15e is a circular annular plane centered on the screw hole central axis O2 and extends in a direction perpendicular to the screw hole central axis O2. The second support surface 15 e contacts the entire seating surface 22 of the cutting insert 2 .

[0063] 1 and 3, the insert support portion 16 is disposed on the outer periphery of the tip of the holder body 11. The insert support portion 16 is disposed between the insert pocket 15 and the chip pocket 14 adjacent to the insert pocket 15 in the counter-tool rotation direction. The insert support portion 16 is disposed between the recessed pockets 15, 14 in the tool circumferential direction, and is formed to protrude relatively toward the outer periphery of the tip of the tool.

[0064] The insert support portion 16 functions as a back metal for the cutting insert 2 attached to the insert pocket 15. The insert support portion 16 supports the cutting insert 2 in the direction opposite to the tool rotation direction. A plurality of insert support portions 16 are provided on the holder body 11. The plurality of insert support portions 16 are arranged on the outer periphery of the tip of the holder body 11 at intervals from one another in the tool circumferential direction.

[0065] 1, 2, and 4, the screw hole 18 extends in the screw hole axial direction (Z-axis direction) around the screw hole central axis O2. The screw hole 18 extends linearly through the insert support portion 16. More specifically, the screw hole 18 extends along the direction of a tangent to an imaginary circle (not shown) centered on the tool central axis O1. In this embodiment, the screw hole 18 has a multi-stage circular hole shape.

[0066] The screw holes 18 open to the bottom surface 15b of the insert pocket 15 and to at least one of the wall surface of the chip pocket 14 facing the counter-tool rotation direction and the outer circumferential surface of the holder body 11. In other words, the screw holes 18 open to the insert pocket 15 and to the chip pocket 14 adjacent to the insert pocket 15 in the counter-tool rotation direction or to the outer circumferential surface of the holder body 11.

[0067] A plurality of screw holes 18 are provided in the holder body 11. The plurality of screw holes 18 are arranged at intervals from one another in the tool circumferential direction on the outer periphery of the tip of the holder body 11. Each screw hole 18 is arranged in each insert support portion 16 and opens to the bottom surface 15b of each insert pocket 15.

[0068] The screw hole 18 has a female screw portion 18a and an opening hole portion 18b that is disposed in the counter tool rotation direction of the female screw portion 18a and is connected to the female screw portion 18a.

[0069] The female screw portion 18a has a circular hole shape and is disposed at least at an end of the screw hole 18 in the tool rotation direction T (an end on one side in the screw hole axial direction). The female screw portion 18a opens to the bottom surface 15b of the insert pocket 15, and more specifically, opens to the second support surface 15e. When the cutting insert 2 is disposed in the insert pocket 15, the female screw portion 18a overlaps with the screw insertion hole 25 of the cutting insert 2 when viewed in the screw hole axial direction.

[0070] The opening hole portion 18b is a circular hole and is disposed at least at the end of the screw hole 18 facing in the counter-tool rotation direction (the end on the other side in the screw hole axial direction). The opening hole portion 18b opens to at least one of the wall surface of the chip pocket 14 facing in the counter-tool rotation direction and the outer circumferential surface of the holder body 11. The inner diameter of the opening hole portion 18b is larger than the inner diameter of the female screw portion 18a.

[0071] 2 and 3, the through hole 17 opens to a region 15f of the bottom surface 15b of the insert pocket 15. That is, the opening of the through hole 17 to the bottom surface 15b is located in the recessed portion 15d. When viewed from the insert axial direction (Z-axis direction), the through hole 17 overlaps with the recessed portion 15d.

[0072] The through hole 17 is arranged radially inward of the screw hole 18 and toward the rear end in the tool axial direction. The through hole 17 is arranged radially inward of the second support surface 15e and toward the rear end in the tool axial direction, adjacent to the second support surface 15e. The through hole 17 is arranged side by side with the second support surface 15e.

[0073] 2 and 4, in this embodiment, the through hole central axis O3, which is the central axis of the through hole 17, and the screw hole central axis O2 extend parallel to each other. The direction in which the through hole central axis O3 extends (through hole axial direction) is the same as the screw hole axial direction, the insert axial direction, and the up-down direction (Z axis direction). One side in the through hole axial direction corresponds to the +Z side, and the other side in the through hole axial direction corresponds to the -Z side.

[0074] In this embodiment, the direction perpendicular to the through-hole central axis O3 is referred to as the through-hole radial direction. Within the through-hole radial direction, the direction approaching the through-hole central axis O3 is referred to as the inner through-hole radial direction, and the direction away from the through-hole central axis O3 is referred to as the outer through-hole radial direction. The direction going around the through-hole central axis O3 is called the through-hole circumferential direction.

[0075] The through hole 17 extends in the through hole axial direction (Z-axis direction) around the through hole central axis O3. The through hole 17 extends linearly through the insert support portion 16. In this embodiment, the through hole 17 has a multi-stage circular hole shape. In FIG. 4, the distance (axis-to-axis dimension) L3 between the through hole central axis O3 and the screw hole central axis O2 is, for example, 2.7 mm or more and 3.0 mm or less.

[0076] The through hole 17 opens to the bottom surface 15b of the insert pocket 15 and to at least one of the wall surface of the chip pocket 14 facing the counter-tool rotation direction and the outer circumferential surface of the holder body 11. That is, the through hole 17 opens to the insert pocket 15 and to the chip pocket 14 adjacent to the insert pocket 15 in the counter-tool rotation direction or to the outer circumferential surface of the holder body 11. As shown in Fig. 1, in this embodiment, both ends (a pair of openings) of the through hole 17 open to the bottom surface 15b of the insert pocket 15 and to the wall surface facing the counter-tool rotation direction of the chip pocket 14 adjacent to the insert pocket 15 in the counter-tool rotation direction.

[0077] A plurality of through holes 17 are provided in the holder body 11. The plurality of through holes 17 are arranged at intervals from one another in the tool circumferential direction on the outer periphery of the tip of the holder body 11.

[0078] As shown in Figure 4, the through hole 17 has a first hole portion 17a that opens to the bottom surface 15b of the insert pocket 15, and a second hole portion 17b that is positioned on the side of the through hole 17 opposite the bottom surface 15b of the first hole portion 17a.

[0079] The first hole portion 17a has a circular hole shape and is disposed at least at an end portion of the through hole 17 in the tool rotation direction T (an end portion on one side in the axial direction of the through hole). The first hole portion 17a opens to the bottom surface 15b of the insert pocket 15, and more specifically, opens to the bottom wall (region 15f) of the recessed portion 15d. The first hole portion 17a constitutes one of a pair of openings of the through hole 17 that faces upward (toward the +Z side).

[0080] When the cutting insert 2 is disposed in the insert pocket 15, a part of the first hole portion 17a overlaps with a part of the cutting insert 2 (for example, a part of each of the rake face 21 and the outer peripheral surface 23) as viewed from the through-hole axial direction. In other words, the cutting insert 2 and the through-hole 17 are arranged to overlap as viewed from the insert axial direction (Z-axis direction).

[0081] The second hole portion 17b has a circular hole shape and is disposed at least at the end of the through hole 17 in the counter-tool rotation direction (the end on the other side in the through hole axial direction). The second hole portion 17b is disposed on the other side in the through hole axial direction than the first hole portion 17a and is connected to the first hole portion 17a. The second hole portion 17b constitutes the other of the pair of openings of the through hole 17 that faces downward (the -Z side).

[0082] The inner diameter dimension of first hole portion 17a is larger than the inner diameter dimension of second hole portion 17b. The inner diameter dimension of first hole portion 17a is the maximum value among the inner diameter dimensions of through hole 17. In this embodiment, as shown in Fig. 4, the dimension of first hole portion 17a in the through hole axial direction (hole depth dimension) is larger than the dimension of second hole portion 17b in the through hole axial direction.

[0083] As shown in Figures 1, 3 and 4, in this embodiment, the fastening member 12 is a fixing screw or the like. The fastening member 12 may be a commercially available screw or the like that is distributed as a general-purpose part. The fastening member 12 is inserted into the screw insertion hole 25 of the cutting insert 2 and screwed into the screw hole 18. This allows the cutting insert 2 to be detachably fixed to the insert pocket 15. A plurality of fastening members 12 are provided on the tool holder 1. The number of fastening members 12 is the same as the number of cutting inserts 2 provided in the indexable cutting tool 10.

[0084] The central axis (screw central axis) of the fastening member 12 is arranged coaxially with the screw hole central axis O2. Therefore, the direction in which the central axis of the fastening member 12 extends (screw axis direction) corresponds to the screw hole axis direction (Z-axis direction). Furthermore, the direction perpendicular to the screw central axis (screw radial direction) corresponds to the screw hole radial direction, and the direction circumferential around the screw central axis (screw circumferential direction) corresponds to the screw hole circumferential direction.

[0085] 4, the fastening member 12 has a multi-stage cylindrical shape and extends in the screw axial direction. The fastening member 12 has a cylindrical screw shaft 12a that is screwed into the female thread portion 18a of the screw hole 18, and a substantially cylindrical screw head 12b that has an outer diameter larger than that of the screw shaft 12a.

[0086] The screw shaft 12a has a male thread on its outer circumferential surface. The screw head 12b has a locking portion to which a work tool such as a wrench (not shown) is locked. In this embodiment, the locking portion is recessed from the end face of the screw head 12b facing away from the screw shaft 12a (the end face facing one side in the screw axis direction; the upper end face). Furthermore, the surface of the screw head 12b facing the screw shaft 12a (the surface facing the other side in the screw axis direction) is formed as a tapered surface 12c whose diameter decreases toward the other side in the screw axis direction (the -Z side).

[0087] The inner diameter of the large diameter hole portion 25a of the screw insertion hole 25 of the cutting insert 2 is larger than the outer diameter of the screw head 12b. The inner diameter of the screw insertion hole 25 other than the large diameter hole portion 25a (the tapered hole portion 25c and the small diameter hole portion 25b) is smaller than the outer diameter of the screw head 12b.

[0088] Therefore, in the process of inserting the fastening member 12 into the screw insertion hole 25 from above (+Z side) and screwing it into the screw hole 18, the tapered surface 12c facing the lower side (-Z side) of the screw head 12b comes into contact with the tapered hole portion 25c of the screw insertion hole 25. When the fastening member 12 is further screwed in, the tapered surface 12c presses the tapered hole portion 25c outward in the thread radial direction toward the through hole 17, thereby drawing the cutting insert 2 closer to the through hole 17. At this time, the outer peripheral surface 23 of the cutting insert 2 is pressed against the two first support surfaces 15c, thereby restricting further movement of the cutting insert 2 and fixing the cutting insert 2 in the insert pocket 15.

[0089] The rotation-preventing member 13 is made of, for example, steel or cemented carbide. The rotation-preventing member 13 is formed of a material having the same hardness as the cutting insert 2 or a material having a hardness less than that. The rotation-preventing member 13 preferably has a hardness higher than that of the holder body 11. When the holder body 11 is made of steel as in this embodiment, the rotation-preventing member 13 is preferably made of, for example, bearing steel (JIS SUJ2) with a Rockwell hardness of 58 HRC or more.

[0090] 1 and 4, the rotation-preventing member 13 is cylindrical or columnar, and in this embodiment, is columnar. The rotation-preventing member 13 is detachably inserted into the through-hole 17. The central axis of the rotation-preventing member 13 is arranged coaxially with the through-hole central axis O3. The diameter (outer diameter) of the rotation-preventing member 13 is, for example, 1.2 mm or more and 1.6 mm or less.

[0091] The rotation-preventing member 13 may be a commercially available knock pin that is distributed as a general-purpose part, or may be a commercially available knock pin that has been additionally machined. When a knock pin is used as the rotation-preventing member 13, the rotation-preventing member 13 can be manufactured inexpensively and easily, which is preferable.

[0092] When the cutting insert 2 is attached to the insert pocket 15, a portion of the anti-rotation member 13 overlaps with a portion of the cutting insert 2 (for example, a portion of each of the rake face 21 and the outer peripheral surface 23) as viewed in the through-hole axial direction (Z-axis direction). In other words, the cutting insert 2 and the anti-rotation member 13 are arranged to overlap as viewed in the insert axial direction (Z-axis direction). In addition, the anti-rotation member 13 contacts the restraining surface 26 of the cutting insert 2 (see FIG. 7).

[0093] A plurality of rotation-preventing members 13 are provided on the tool holder 1. The number of rotation-preventing members 13 is the same as the number of cutting inserts 2 provided on the indexable cutting tool 10.

[0094] 4, the rotation-preventing member 13 extends in the through-hole axial direction (Z-axis direction). The dimension (total length) of the rotation-preventing member 13 in the through-hole axial direction is greater than the dimension (hole depth) of the first hole portion 17a of the through-hole 17 in the through-hole axial direction. Therefore, when the rotation-preventing member 13 is inserted into the through-hole 17 until it hits the step portion 17c between the first hole portion 17a and the second hole portion 17b, the upper end of the rotation-preventing member 13 protrudes upward (toward the +Z side) from the through-hole 17. In other words, the upper end of the rotation-preventing member 13 is disposed protruding above the bottom surface 15b of the insert pocket 15.

[0095] The rotation prevention member 13 has an insertion portion 13 a that is inserted into the through hole 17 and a protrusion 13 b that protrudes from the through hole 17 .

[0096] The insertion portion 13a has a cylindrical shape extending in the through-hole axial direction (Z-axis direction). The insertion portion 13a is arranged in a portion of the rotation-preventing member 13 other than the upper end portion. The insertion portion 13a is inserted into the first hole portion 17a. The lower end surface of the insertion portion 13a contacts the step portion 17c of the through-hole 17 from above (the +Z side).

[0097] The protruding portion 13b has a cylindrical shape extending in the axial direction of the through hole. The protruding portion 13b is arranged at the upper end of the rotation-preventing member 13. The protruding portion 13b protrudes upward from the first hole portion 17a. The protruding portion 13b is arranged to protrude upward beyond the bottom surface 15b of the insert pocket 15. The dimension of the protruding portion 13b in the axial direction of the through hole is smaller than the dimension of the insertion portion 13a in the axial direction of the through hole.

[0098] If the amount of protrusion of the protruding portion 13b upward from the through-hole 17 is L1, then 0.08 mm≦L1≦0.25 mm is satisfied. The protruding amount L1 is preferably 0.1 mm or more, and more preferably 0.2 mm or more.

[0099] Furthermore, the protrusion amount L1 is smaller than the maximum dimension L2 (height dimension from the seating surface 22 to the upper end of the constraint surface 26) of the constraint surface 26 of the cutting insert 2 in the insert axial direction. The height dimension L2 of the constraint surface 26 is, for example, not more than the protrusion amount L1+0.25 mm. Specifically, in this embodiment, the height dimension L2 of the constraint surface 26 is, for example, about 0.25 mm.

[0100] In this embodiment, the diameter (outer diameter) of the insertion portion 13a and the diameter of the protrusion 13b are the same. That is, there is no step or the like between the insertion portion 13a and the protrusion 13b, and the insertion portion 13a and the protrusion 13b are connected so as to be smoothly continuous in the axial direction of the through-hole.

[0101] In this embodiment, the rotation-preventing member 13 is fitted into the through-hole 17 by an interference fit. That is, the diameter (outer diameter) of the insertion portion 13a of the rotation-preventing member 13 is equal to or larger than the inner diameter of the first hole portion 17a of the through-hole 17. Specifically, the diameter of the insertion portion 13a is the maximum diameter dmax of the rotation-preventing member 13, and the inner diameter of the first hole portion 17a is the maximum inner diameter Dmax of the through-hole 17, and in this embodiment, dmax≧Dmax.

[0102] 6 and 7, the protrusion 13b comes into contact with the restraining surface 26, thereby restricting the rotation of the cutting insert 2 around the insert central axis O4. Specifically, the convexly curved outer peripheral surface of the protrusion 13b comes into contact with the concavely curved restraining surface 26 from the outside in the insert radial direction and from the insert circumferential direction, thereby restricting the rotation of the cutting insert 2 in the insert circumferential direction.

[0103] 3 and 5(a), the fastening member 12 is inserted into the screw insertion hole 25 from the upper side (+Z side) and rotated to one side θ1 in the insert circumferential direction, whereby the fastening member 12 is screwed into the screw hole 18. At this time, in FIG. 4, the tapered surface 12c of the fastening member 12 and the tapered hole portion 25c of the screw insertion hole 25 are pressed against each other while the fastening member 12 rotates to one side θ1 in the insert circumferential direction, and the cutting insert 2 also rotates to one side θ1 in the insert circumferential direction.

[0104] As a result, as shown in Fig. 7, the restraining surface 26 of the cutting insert 2 comes into contact with the protruding portion 13b of the rotation-preventing member 13 from one side θ1 in the circumferential direction of the insert, and the restraining surface 26 and the protruding portion 13b are locked together. The locking of the restraining surface 26 and the protruding portion 13b restricts the cutting insert 2 from further rotating toward the one side θ1 in the circumferential direction of the insert. In Fig. 7, a virtual circle (not shown) centered on the insert central axis O4 and including the outermost peripheral edge of the seating surface 22 intersects with the protruding portion 13b of the rotation-preventing member 13.

[0105] In this way, the constraint surface 26 and the protrusion 13b cooperate to position the cutting insert 2 and restrict rotation of the cutting insert 2 during cutting. During cutting, it is preferable that a cutting resistance (cutting load) acts on the cutting edge 24 toward one side θ1 in the circumferential direction of the insert. In this case, rotation of the cutting insert 2 is more reliably prevented.

[0106] In the tool holder 1 and indexable cutting tool 10 of the present embodiment described above, the anti-rotation member 13 is formed separately from the holder body 11. Therefore, even for a small-diameter tool holder 1, manufacturing is easier than with the conventional configuration in which the anti-rotation member and the holder body are manufactured as a single unit.

[0107] Furthermore, even if the rotation-preventing member 13 is damaged after repeated use of the tool in cutting processes, only the rotation-preventing member 13 needs to be replaced, without replacing the holder body 11. This results in cost reduction, is economical, and extends the life of the tool holder 1 as a whole.

[0108] More specifically, the rotation prevention mechanism of this embodiment employs a simple structure in which an insertion portion 13a of a cylindrical rotation prevention member 13 is inserted into a multi-stage circular through-hole 17 of the insert pocket 15. Then, a protruding portion 13b of the rotation prevention member 13 that protrudes outward from the through-hole 17 is brought into contact with a restraining surface 26 of the cutting insert 2, thereby restricting the rotation of the cutting insert 2.

[0109] Therefore, by using a small-diameter round insert 2 with a rake face 21 having a diameter of less than 8 mm, even when each part of the tool holder 1 is reduced in size to match the insert size, the anti-rotation member 13 and the through hole 17 can be easily manufactured, without requiring increased worker skill or increased manufacturing time. Furthermore, there is no need to introduce dedicated equipment. Therefore, according to this embodiment, not only are there no manufacturing issues that may be expected when using a small-diameter round insert 2, but manufacturability can also be further improved.

[0110] Furthermore, because rotation-preventing member 13 is inserted into through-hole 17, rotation-preventing member 13 can be easily replaced. Specifically, any rod-shaped object can be inserted into through-hole 17 from the side opposite protrusion 13b (the lower side), and then the rod-shaped object can be struck with a hammer or the like to push rotation-preventing member 13 toward protrusion 13b (the upper side), thereby removing it from through-hole 17. Furthermore, by inserting a new rotation-preventing member 13 into through-hole 17, rotation-preventing member 13 can be positioned with precision, completing the installation. Therefore, the replaceability of rotation-preventing member 13 can be improved.

[0111] Unlike the present embodiment, if the rotation-preventing member is inserted into a blind hole (a non-through hole), replacing the rotation-preventing member requires grasping the tip (protruding portion) of the rotation-preventing member protruding from the bottom of the insert pocket with pliers or the like and pulling it out. In this case, the use of pliers or the like requires securing a certain amount of gripping space for the protruding portion (a dimension corresponding to the protruding amount L1), which results in the protruding portion protruding unnecessarily long. This makes the rotation-preventing member more susceptible to chipping or bending, reducing the durability of the rotation-preventing member.

[0112] In contrast, in this embodiment, as described above, the rotation-preventing member 13 can be knocked out of the through-hole 17 with a hammer or the like, so even if the protrusion amount of the protrusion 13b of the rotation-preventing member 13 is small, there is no impact on the replacement work. The protrusion amount of the protrusion 13b necessary to prevent rotation of the cutting insert 2 can be set small, making it less susceptible to the effects of impacts during cutting processing and reducing the occurrence of chipping or bending of the rotation-preventing member 13. Therefore, the durability of the rotation-preventing member 13 can be improved.

[0113] As described above, according to the present embodiment, it is possible to provide a tool holder 1 and an indexable cutting tool 10 equipped with an anti-rotation mechanism that can improve manufacturability, durability, and replaceability when a small-diameter round insert 2 is used.

[0114] In this embodiment, the through hole 17 has a first hole portion 17a that opens to the bottom surface 15b of the insert pocket 15, and a second hole portion 17b that is arranged on the opposite side (lower side) of the through hole 17 from the bottom surface 15b of the first hole portion 17a, and the inner diameter dimension of the first hole portion 17a is larger than the inner diameter dimension of the second hole portion 17b.

[0115] In this case, through hole 17 is a multi-step circular hole having first hole portion 17a and second hole portion 17b with different inner diameters. When attaching rotation-preventing member 13 to through hole 17, as rotation-preventing member 13 is inserted through first hole portion 17a, the lower end of rotation-preventing member 13 (the lower end of insertion portion 13a) comes into contact with step portion 17c between first hole portion 17a and second hole portion 17b, thereby preventing rotation-preventing member 13 from being inserted further into through hole 17. This makes it easy to position rotation-preventing member 13 relative to through hole 17, and the amount of protrusion of protrusion 13b from through hole 17 is stably maintained at a predetermined size (i.e., a constant value).

[0116] Furthermore, since the through hole 17 has a structure in which the second hole portion 17b having a smaller diameter than the first hole portion 17a is provided, it is possible to ensure a sufficient thickness of the holder body 11. In particular, in the case of a tool holder 1 having a small diameter, it is easy to obtain the effect of suppressing a decrease in the strength of the holder body 11.

[0117] In this embodiment, the rotation prevention member 13 is cylindrical or columnar, and when the amount of protrusion of the protrusion 13b from the through-hole 17 is L1, the relationship is 0.08 mm≦L1≦0.25 mm.

[0118] In this case, because the rotation-preventing member 13 is cylindrical or columnar (columnar in this embodiment), it is possible to eliminate corners (i.e., points where stress concentrates) on the outer peripheral surface of the rotation-preventing member 13. As a result, even if a large force is applied between the restraining surface 26 of the cutting insert 2 and the rotation-preventing member 13 during cutting, it is possible to suppress sudden breakage of the rotation-preventing member 13. The cutting insert 2, whose rotation is stably restricted, allows for stable cutting with high precision.

[0119] Furthermore, when the protrusion amount L1 of the protrusion 13b of the rotation-preventing member 13 is 0.08 mm or more, the protrusion 13b is brought into stable contact with the constraint surface 26 of the cutting insert 2. The protrusion 13b and the constraint surface 26 cooperate reliably, providing an anti-rotation effect. In other words, the rotation-preventing member 13 can stably restrict the rotation of the cutting insert 2. Note that if the protrusion amount L1 is 0.1 mm or more, the above effect becomes more pronounced, and therefore it is preferable. More preferably, the protrusion amount L1 is 0.2 mm or more.

[0120] Furthermore, if the protrusion amount L1 of the protrusion 13b of the rotation-preventing member 13 is 0.25 mm or less, deflection and deformation of the rotation-preventing member 13 are suppressed even when a large force is applied to the rotation-preventing member 13 from the cutting insert 2 during cutting. This ensures the durability of the rotation-preventing member 13.

[0121] Furthermore, in accordance with the small protrusion 13b, the size of the constraint surface 26 of the cutting insert 2 that cooperates with this protrusion 13b can also be kept small. Since the thickness of the cutting insert 2 can be ensured to be large, cracks and the like of the cutting insert 2 are prevented.

[0122] In this embodiment, the through hole 17 overlaps with the recessed portion 15d when viewed from the insert axial direction (Z-axis direction) (see FIG. 3). For example, unlike the present embodiment, the above-described configuration of the present embodiment can suppress thinning of the holder body 11 caused by providing the through holes 17, compared to when the through holes are formed in a portion other than the recessed portion. According to the present embodiment, the strength of the holder body 11 is ensured while the above-described excellent effects are obtained.

[0123] In this embodiment, the rotation prevention member 13 (insertion portion 13a) is fitted into the through-hole 17 (first hole portion 17a) by an interference fit. In this case, the rotation-preventing member 13 is prevented from falling out of the through-hole 17. Even if the rotation-preventing member 13 is a small part as in this embodiment, it is possible to prevent the rotation-preventing member 13 from falling out of the tool and being lost.

[0124] In this embodiment, the cutting insert 2 and the rotation-preventing member 13 are arranged to overlap each other when viewed from the insert axial direction (Z-axis direction). In this case, the cutting insert 2 is disposed so as to cover the anti-rotation member 13 from above (+Z side), so even if the anti-rotation member 13 unintentionally moves upward relative to the through-hole 17 during cutting, the anti-rotation member 13 comes into contact with the cutting insert 2 from below (-Z side). This prevents the anti-rotation member 13 from slipping out of the through-hole 17 to the above and falling off.

[0125] In this embodiment, the restraining surface 26 of the cutting insert 2 is formed into a concave curved surface. In this case, even if a large force is applied to the cutting insert 2 during cutting, the constraint surface 26 is prevented from becoming a starting point for cracking of the cutting insert 2. As a result, fracture or the like of the cutting insert 2 is prevented.

[0126] In this embodiment, the constraint surface 26 of the cutting insert 2 is open not only to the outer circumferential surface 23 but also to the seating surface 22. That is, the constraint surface 26 reaches the seating surface 22. In this case, since the concave restraining surface 26 is disposed close to the seating surface 22, it is possible to dispose the restraining surface 26 away from the cutting edge 24. This ensures strength in the vicinity of the cutting edge 24, particularly in the case of a small-diameter round insert 2, and prevents breakage of the insert.

[0127] In this embodiment, the height L2 of the restraining surface 26 is equal to or less than the protrusion amount L1 of the rotation-preventing member 13 + 0.25 mm. In this case, the restraining surface 26 can be disposed sufficiently far from the cutting edge 24. That is, a sufficient distance can be secured between the restraining surface 26 and the cutting edge 24. As a result, damage to the insert can be suppressed.

[0128] The present invention is not limited to the above-described embodiment, and modifications to the configuration are possible within the scope of the invention, as described below.

[0129] In the above-described embodiment, the rotation prevention member 13 is tightly fitted into the through hole 17, thereby preventing the rotation prevention member 13 from slipping out of the through hole 17, but this configuration is not limited to this. For example, the insertion portion 13a of the rotation prevention member 13 may have a male thread, and the through hole 17 may have a female thread, and these may be screwed together to prevent the rotation prevention member 13 from slipping out of the through hole 17.

[0130] Alternatively, anti-rotation member 13 may have a multi-stage cylindrical or columnar shape, with protruding portion 13b having a larger outer diameter than insertion portion 13a. In this case, through hole 17 may have a constant inner diameter over the entire length in the axial direction of the through hole.

[0131] Furthermore, although not specifically shown, the following configuration may be employed. That is, the rotation-preventing member has a multi-stage cylindrical or columnar shape, and the diameter dimension (outer diameter dimension) of the lower end of the rotation-preventing member is the maximum diameter of the rotation-preventing member. Also, the through hole has a fixed inner diameter dimension. When the rotation-preventing member is inserted into the through hole from below, a step formed between the lower end and a portion of the rotation-preventing member other than the lower end may engage with an opening facing downward of the through hole or a portion inside the through hole (such as a step portion), thereby preventing the rotation-preventing member from slipping out of the through hole to the upper side.

[0132] Although not specifically shown, the insert pocket 15 may have a countersunk hole disposed in the bottom surface 15b of the insert pocket 15. When viewed from the insert axial direction (Z-axis direction), at least a portion of the countersunk hole is disposed in the recessed portion 15d. The countersunk hole is disposed alongside the second support surface 15e and is recessed below the second support surface 15e. The depth of the countersunk hole, i.e., the depth recessed below the second support surface 15e, is, for example, about 0.05 mm. In this case, the through hole 17 opens at the bottom of the countersunk hole. The central axis of the countersunk hole is disposed coaxially with the through hole central axis O3. In the above configuration, when manufacturing the holder body 11, when drilling the through hole 17 using a drill or the like, the countersunk hole can be used as a guide to easily position the through hole 17, and the through hole 17 can be drilled with high precision.

[0133] In the above-described embodiment, the through hole 17 has the first hole portion 17a and the second hole portion 17b, but this is not limiting. For example, the through hole 17 may have one or more other hole portions (third hole portion, fourth hole portion, etc.) that are arranged between the first hole portion 17a and the second hole portion 17b and have inner diameters different from those of the hole portions 17a and 17b.

[0134] In the above-described embodiment, the through-hole central axis O3, which is the central axis of the through-hole 17, and the screw-hole central axis O2, which is the central axis of the screw hole 18, extend parallel to each other, but this is not limiting. The through-hole central axis O3 may extend at an angle with respect to the screw-hole central axis O2.

[0135] In the above-described embodiment, the screw hole 18 is formed so as to penetrate the insert support portion 16, but this is not limiting. The screw hole 18 may be a bottomed stop hole that opens only to the bottom surface 15b of the insert pocket 15.

[0136] In the above-described embodiment, the fastening member 12 for fixing the cutting insert 2 to the insert pocket 15 (holder body 11) is a fixing screw or the like, but is not limited thereto. The fastening member may be, for example, a wedge member for detachably fixing the cutting insert 2 to the insert pocket 15.

[0137] In the above embodiment, three cutting inserts 2 are provided at equal intervals in the circumferential direction of the tool on the tool holder 1, but this is not limiting. The three cutting inserts 2 may be arranged at unequal intervals in the circumferential direction of the tool. Furthermore, the number of cutting inserts 2 provided in the tool holder 1 is not limited to three. The number of cutting inserts 2 provided in the tool holder 1 may be two or less, or may be four or more.

[0138] When the number of cutting inserts 2 provided in the tool holder 1 is small, the number of chip pockets 14 and the number of insert pockets 15 also become small accordingly. In this case, the opening facing downward of the through hole 17 (the second hole portion 17b in the above-described embodiment) may open to the outer peripheral surface of the holder body 11.

[0139] In the above embodiment, as shown in Fig. 5(a), when viewed from above with the rake face 21 facing forward, the clockwise rotation direction about the insert central axis O4 corresponds to one side θ1 in the circumferential direction of the insert, and the counterclockwise rotation direction corresponds to the other side θ2 in the circumferential direction of the insert. However, this is not limited to this. When viewed from above with the rake face 21 facing forward, the counterclockwise rotation direction about the insert central axis O4 may correspond to one side θ1 in the circumferential direction of the insert, and the clockwise rotation direction may correspond to the other side θ2 in the circumferential direction of the insert.

[0140] Furthermore, it goes without saying that the above-described action and effect of the rotation prevention mechanism of the present invention can also be obtained when applied to a cutting insert 2 having a rake face 21 with a diameter of 8 mm or more.

[0141] In the above-described embodiment, the indexable cutting tool 10 is an example of a milling tool such as an indexable end mill, but the present invention is not limited to this. The present invention can also be applied to a turning tool such as an indexable cutting tool.

[0142] In the above-described embodiment, the material of the substrate of the cutting insert 2 may be, in addition to cemented carbide containing tungsten carbide (WC) and cobalt (Co), for example, cermet, high-speed steel, ceramics consisting of titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, and mixtures thereof, cubic boron nitride sintered body, diamond sintered body, or ultra-high pressure sintered body obtained by sintering a hard phase consisting of polycrystalline diamond or cubic boron nitride with a binder phase such as ceramics or iron group metal under ultra-high pressure.

[0143] The present invention may be combined with the various configurations described in the above-described embodiments and modifications, and may also include additions, omissions, substitutions, and other modifications of the configurations, without departing from the spirit of the present invention. Furthermore, the present invention is not limited to the above-described embodiments, but is limited only by the claims. [Industrial Applicability]

[0144] The tool holder and indexable cutting tool of the present invention are provided with a rotation prevention mechanism that can improve manufacturability, durability, and replaceability when using small-diameter round inserts, and therefore have industrial applicability. [Explanation of symbols]

[0145] 1...tool holder, 2...cutting insert, 10...indexable cutting tool, 11...holder body, 12...fastening member, 13...rotation prevention member, 13a...insertion portion, 13b...protrusion portion, 15...insert pocket, 15a...side surface, 15b...bottom surface, 15c...first support surface, 15e...second support surface, 17...through hole, 17a...first hole portion, 17b...second hole portion, 21...rake face, 22...seating surface, 23...outer peripheral surface, 26...restraint surface, L1...protrusion amount, O4...insert central axis

Claims

1. A tool holder to which a disc-shaped cutting insert having a rake face diameter of less than 8 mm is removably attached, A holder body; a fastening member that fixes the cutting insert to the holder body; a rotation prevention member that is detachably attached to the holder body and that contacts a restraining surface that is disposed on an outer peripheral surface of the cutting insert, The holder body includes: an insert pocket in which the cutting insert is mounted; a through hole that opens to the bottom surface of the insert pocket, The insert pocket is one or more first support surfaces disposed on the side surfaces of the insert pocket and in contact with the outer peripheral surface of the cutting insert; a second support surface disposed on a bottom surface of the insert pocket and in contact with the seating surface of the cutting insert; the through hole is aligned with the second support surface; The rotation prevention member is an insertion portion to be inserted into the through hole; a protrusion protruding from the through hole, When the protrusion contacts the constraint surface, rotation of the cutting insert around the insert central axis is restricted. Tool holder.

2. The through hole is a first hole portion that opens to a bottom surface of the insert pocket; a second hole portion disposed on the opposite side of the through hole from the bottom surface of the first hole portion, The inner diameter of the first hole portion is larger than the inner diameter of the second hole portion. The tool holder according to claim 1 .

3. the rotation prevention member is cylindrical or columnar, When the amount of protrusion of the protruding portion from the through hole is L1, 0.08 mm≦L1≦0.25 mm; 3. A tool holder according to claim 1 or 2.

4. A disc-shaped cutting insert having a rake face with a diameter dimension of less than 8 mm; a tool holder to which the cutting insert is detachably attached, The cutting insert has a restraint surface disposed on an outer peripheral surface of the cutting insert and reaching a seating surface of the cutting insert; The tool holder comprises: A holder body; a fastening member that fixes the cutting insert to the holder body; a rotation prevention member that is detachably attached to the holder body and that contacts the restraint surface, The holder body includes: an insert pocket in which the cutting insert is mounted; a through hole that opens to the bottom surface of the insert pocket, The insert pocket is one or more first support surfaces disposed on the side surfaces of the insert pocket and in contact with the outer peripheral surface of the cutting insert; a second support surface disposed on a bottom surface of the insert pocket and in contact with the seating surface of the cutting insert; the through hole is aligned with the second support surface; The rotation prevention member is an insertion portion to be inserted into the through hole; a protrusion protruding from the through hole, When the protrusion contacts the constraint surface, rotation of the cutting insert around the insert central axis is restricted. Indexable cutting tool.

5. The through hole is a first hole portion that opens to a bottom surface of the insert pocket; a second hole portion disposed on the opposite side of the through hole from the bottom surface of the first hole portion, The inner diameter of the first hole portion is larger than the inner diameter of the second hole portion. The indexable cutting tool according to claim 4.

6. the rotation prevention member is cylindrical or columnar, When the amount of protrusion of the protruding portion from the through hole is L1, 0.08 mm≦L1≦0.25 mm; The indexable cutting tool according to claim 4 or 5.

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