Cutting insert clamping structure, tip replaceable cutting tool, and cutting insert

Abstract

To reduce cost by forming a cutting insert compact, to stably and firmly hold the cutting insert with a supporter, and to ensure rigidity of the cutting insert.SOLUTION: This clamping structure comprises: a cutting insert 2; and a supporter 3 that holds the cutting insert 2. The insert front 21 of the cutting insert 2 includes a V-shaped cutting edge 24, and a pair of back-facing steps 25 arranged on the rear end side of the insert front 21. An insert rear 22 includes a pair of insert outer surfaces 22c facing left and right. Each insert outer surface 22c extends outwardly in left and right direction toward the rear side. The supporter 3 includes a pocket 33 in which the cutting insert 2 is disposed, and a pair of arms 32 which can approach each other. Each arm 32 includes an arm front end surface 32a that comes into contact with each of the back-facing step 25 from the rear side, and an arm inner surface 32b that comes into contact with each of the insert outer surface 22c from the horizontal outside.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a clamping structure for a cutting insert, an indexable cutting tool, and a cutting insert. [Background technology]

[0002] Conventionally, an indexable cutting tool is known, for example, as described in Patent Document 1. This indexable cutting tool includes a tool body having an insert mounting seat, a cutting insert made of a hard material, a carrier body (supporter) that holds the cutting insert, and a clamping member that fixes the cutting insert and the carrier body to the insert mounting seat. In Patent Document 1, the use of the carrier body enables the external dimensions of the expensive cutting insert to be reduced, resulting in cost reduction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2009 / 047166 Summary of the Invention [Problem to be solved by the invention]

[0004] In this type of indexable cutting tool, it is difficult for the supporter to stably hold the miniaturized cutting insert. In particular, cutting inserts with a small V-shaped cutting edge angle of, for example, 35° when viewed from the top and bottom (from the rake face side) tend to have difficulty in firmly holding the cutting insert with the supporter. This is because the cutting insert has a long, slender shape in the front-to-back direction, and it is difficult to ensure the thickness of the pair of supporter arms that clamp the cutting insert from the left and right. However, if the supporter cannot stably hold the cutting insert, a gap will form at the contact surface between the cutting insert and the supporter when subjected to cutting load during cutting, or the cutting insert will become misaligned.

[0005] Therefore, as shown in Fig. 25 of Patent Document 1, for example, a configuration can be considered in which a pair of outer surfaces facing the left and right directions of the cutting insert are each provided with a recess, and a pair of arms of the support are each provided with a protrusion that engages with the recess, thereby firmly holding the cutting insert. With this configuration, it is possible to prevent the cutting insert from shifting in the front-rear direction.

[0006] However, in this case, it is difficult to ensure the insert rigidity. Specifically, when the cutting edge receives a cutting load from the left and right during cutting, a force that rotates the cutting insert acts, and cracks are likely to occur starting from the concave corner (neck portion) located at the rear end of the concave portion of the cutting insert.

[0007] The present invention aims to provide a cutting insert clamping structure, an indexable cutting tool, and a cutting insert that can make the cutting insert compact and reduce costs, while firmly and stably holding the cutting insert with a supporter and ensuring the rigidity of the cutting insert. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides the following means.

[0009] [Aspect 1 of the present invention] A clamp structure for a cutting insert that is detachably attached to an insert attachment seat of a tool body by a clamp member, the clamp structure comprising: a cutting insert extending in a front-rear direction along an insert central axis; and a supporter that holds the cutting insert, the cutting insert having an insert front portion whose dimension in the left-right direction increases from the front end toward the rear side, and an insert rear portion that is connected to the rear end surface of the insert front portion and whose dimension in the left-right direction increases from the connecting portion with the insert front portion toward the rear side, the insert front portion having a V-shaped cutting edge that is arranged on a ridge line portion that connects at least an upper surface of the insert front portion to an outer circumferential surface, and a cutting edge that is arranged on the rear end surface of the insert front portion and faces rearward, a pair of rearward-facing step portions protruding in the left-right direction from the connection portion with the rear portion of the insert, the rear portion of the insert having a pair of insert outer surfaces facing in the left-right direction, each of the insert outer surfaces extending outward in the left-right direction as it approaches the rear side, the supporter having a concave shape recessed rearward from the front end of the supporter, a pocket in which the cutting insert is placed, and a pair of arms that can move toward each other so as to narrow the left-right dimension of the pocket, the cutting edge of the cutting insert being positioned forward of the pocket, and each of the arms having an arm front end surface that contacts the rearward-facing step portions from the rear side, and an arm inner surface that contacts the insert outer surface from the outside in the left-right direction.

[0010] In the clamping structure of the cutting insert of the present invention, the supporter holds the cutting insert, thereby making it possible to reduce the outer dimensions of the cutting insert made of an expensive hard material such as cemented carbide. This reduces tool costs. Specifically, the clamping structure of the cutting insert of the present invention can reduce the amount of cemented carbide raw material used by 50% or more compared to a general cutting insert that conforms to ISO standards and has the same outer shape as this clamping structure.

[0011] In the present invention, when the cutting insert is clamped, i.e., when the cutting insert and the supporter are attached to the insert mounting seat by the clamping member, the pair of arms move toward each other to narrow the left-right dimension of the pocket. Specifically, the clamping member is engaged with the supporter, and a pulling force, for example, toward the rear, is applied to the supporter via the clamping member, thereby pressing the arms against the side walls of the insert mounting seat and elastically deforming them, thereby bringing the pair of arms toward each other. As the pair of arms move toward each other, the left-right dimension (width dimension) of the pocket decreases, and the cutting insert is sandwiched between the pair of arms and fixed in the pocket.

[0012] More specifically, in the present invention, when clamping, the inner arm surfaces of the pair of arms contact the pair of outer insert surfaces at the rear of the cutting insert from the outside in the left-right direction. Each insert outer surface extends outward in the left-right direction as it approaches the rear. Therefore, when the pair of arms move toward each other and the inner arm surfaces press the outer insert surfaces inward in the left-right direction, a pulling force that pulls the cutting insert toward the rear side is generated due to the action of the wedge structure (wedge function). This allows the inner arm surfaces to stably press the outer insert surfaces.

[0013] The front end surfaces of the arms contact the rear side of a pair of rearward-facing stepped portions at the front of the cutting insert. The wedge function generates a rearward pulling force on the cutting insert, stabilizing the contact (pressing state) between the arm front end surfaces and the rearward-facing stepped portions. Therefore, according to the present invention, the cutting insert can be firmly and stably fixed by the supporter.

[0014] Specifically, in the present invention, of the cutting loads (cutting resistance) acting on the cutting insert during cutting, the rearward force (thrust force) can be stably received by the front end surface of the supporter arm. Furthermore, of the cutting loads acting on the cutting insert, the left-right force (feed force) can be stably received by the inner surface of the arm utilizing the wedge function. More specifically, even if a force that rotates the cutting insert within the pocket due to the feed force is generated, the wedge-shaped outer surface of the insert and the inner surface of the arm can stably receive the force, thereby preventing unintended rotation of the cutting insert. Therefore, problems such as gaps occurring at the contact surfaces between the cutting insert and the supporter and misalignment of the cutting insert are suppressed.

[0015] Furthermore, even when a force is applied to pull the cutting insert forward out of the pocket due to relative movement with the workpiece, such as at the end of cutting, the wedge-shaped outer surface of the insert and inner surface of the arm can prevent the cutting insert from coming out of the pocket.

[0016] Furthermore, the cutting insert of the present invention does not have a recess as shown in Fig. 25 of the aforementioned Patent Document 1 (WO 2009 / 047166). Therefore, unlike conventional techniques, cracks originating from the recessed corner (neck portion) located at the rear end of the recess do not occur. Furthermore, by not providing a recess in the present invention, the cutting insert can have a large dimension (width) in the left-right direction. This increases the rigidity of the cutting insert.

[0017] As described above, according to the present invention, the cutting insert can be made compact and costs can be reduced, while the cutting insert can be firmly and stably held by the supporter and the rigidity of the cutting insert can be ensured.

[0018] [Aspect 2 of the present invention] The clamping structure of a cutting insert described in aspect 1, wherein two cutting edges are provided on the front portion of the insert, one of the two cutting edges is located on the ridge portion connecting the upper surface and outer peripheral surface of the front portion of the insert, and the other is located on the ridge portion connecting the lower surface and outer peripheral surface of the front portion of the insert, and the shapes of the front portion of the insert and the rear portion of the insert match when the cutting insert is flipped 180 degrees in the front-to-back direction and rotated 90 degrees around the center axis of the insert.

[0019] In this case, the cutting insert has two cutting edges at the front and two at the rear, making it a so-called four-corner insert. Since one cutting insert has a total of four cutting edges, the tool life of the cutting insert can be extended.

[0020] [Embodiment 3 of the present invention] The clamping structure for a cutting insert according to aspect 1 or 2, wherein the rearward step portion widens in a direction perpendicular to the central axis of the insert, or extends rearward as it extends outward in the left-right direction.

[0021] For example, unlike the above configuration, if the rearward step portion extends toward the front as it moves outward in the left-right direction, when the cutting insert is subjected to cutting loads (especially thrust force) during cutting processing, the pair of arms may be more likely to displace away from each other in the left-right direction (the pair of arms may be more likely to separate).

[0022] In contrast, according to the above-described configuration of the present invention, even if the cutting insert is subjected to a cutting load (especially a thrust force), the pair of arms will not be displaced apart in the left-right direction due to the shape of the rearward-facing step portion (the pair of arms will not be spaced apart). Therefore, the above-described effect of being able to firmly hold the cutting insert by the supporter is stably achieved.

[0023] [Aspect 4 of the present invention] A clamping structure for a cutting insert according to any one of aspects 1 to 3, wherein the total length of the cutting insert in the anterior-posterior direction is 2 / 3 or less of the anterior-posterior direction dimension between the anterior-posterior center of the clamping structure for the cutting insert and the front end of the cutting edge.

[0024] In this case, the overall length of the cutting insert in the front-rear direction can be kept small, which further enhances the effect of reducing tool costs.

[0025] [Embodiment 5 of the present invention] An indexable cutting tool comprising: the clamping structure for a cutting insert according to any one of aspects 1 to 4; the tool body having the insert mounting seat; and the clamping member that fixes the clamping structure for the cutting insert to the insert mounting seat.

[0026] According to the indexable cutting tool of the present invention, the above-mentioned excellent effects can be obtained.

[0027] [Aspect 6 of the present invention] an indexable cutting tool comprising: the clamping structure for a cutting insert according to aspect 2; the tool body having the insert mounting seat; and the clamping member for fixing the clamping structure for the cutting insert to the insert mounting seat; wherein the rear portion of the insert is disposed on the front end surface of the rear portion of the insert, facing forward, and has a pair of forward-facing step portions that protrude in the vertical direction from the connection portion between the rear portion of the insert and the front portion of the insert; the insert mounting seat has a seat member that contacts the clamping structure of the cutting insert from below, and the seat member has a supporter support surface that contacts the underside of the supporter, an insert support surface that contacts the underside of the front portion of the insert, and a recessed portion that is disposed between the supporter support surface and the insert support surface, recessed downward, and into which the forward-facing step portions are inserted.

[0028] According to the indexable cutting tool of the present invention, the above-mentioned excellent effects can be obtained. In addition, the seat member of the insert mounting seat has a recessed portion, and by locating the forward-facing step on the lower side of the rear part of the insert within the recessed portion, it is possible to stabilize the contact state between the lower surface of the supporter and the supporter support surface, and also to stabilize the contact state between the lower surface of the front part of the insert and the insert support surface.

[0029] That is, the seat member can stably support the clamping structure of the cutting insert from below, and therefore the seat member can stably receive the downward force (principal force) of the cutting load (cutting resistance) acting on the cutting insert during cutting.

[0030] [Embodiment 7 of the present invention] a cutting insert extending in the front-to-rear direction along the insert central axis, the cutting insert having an insert front portion whose dimension in the left-to-right direction increases from the front end toward the rear side; and an insert rear portion connected to the rear end surface of the insert front portion and whose dimension in the left-to-right direction increases from the connection portion with the insert front portion toward the rear side, the insert front portion having a V-shaped cutting edge disposed on a ridge line where at least the upper surface of the insert front portion is connected to the outer peripheral surface, and a pair of rearward-facing steps disposed on the rear end surface of the insert front portion, facing rearward, and protruding in the left-to-right direction from the connection portion between the insert front portion and the insert rear portion, the insert rear portion having a pair of insert outer side surfaces facing in the left-to-right direction, each of the insert outer side surfaces extending outward in the left-to-right direction toward the rear side.

[0031] According to the cutting insert of the present invention, the same excellent effects as those of the clamping structure of the cutting insert described above can be obtained. [Effects of the Invention]

[0032] According to the above-described aspects of the cutting insert clamping structure, indexable cutting tool, and cutting insert of the present invention, the cutting insert can be made compact to reduce costs, while the supporter can firmly and stably hold the cutting insert, and the rigidity of the cutting insert can also be ensured. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 is a perspective view showing a clamping structure of a cutting insert and a part of an indexable cutting tool according to the present embodiment. [Figure 2] FIG. 2 is a top view showing a clamping structure of a cutting insert and a part of an indexable cutting tool. [Figure 3] FIG. 3 is a side view showing a clamping structure of the cutting insert and a part of the indexable cutting tool. [Figure 4] FIG. 4 is a front view showing a clamping structure of a cutting insert and an indexable cutting tool. [Figure 5] FIG. 5 is a perspective view showing a clamping structure of the cutting insert. [Figure 6] FIG. 6 is a top view showing the clamping structure of the cutting insert. [Figure 7] FIG. 7 is a side view showing a clamping structure of the cutting insert. [Figure 8] FIG. 8 is a front view showing the clamping structure of the cutting insert. [Figure 9] FIG. 9 is a perspective view showing a cutting insert. [Figure 10] 10(a) is a top view showing the cutting insert, FIG. 10(b) is a side view showing the cutting insert, and FIG. 10(c) is a front view showing the cutting insert. [Figure 11] FIG. 11 is a perspective view showing a supporter. [Figure 12] FIG. 12 is a perspective view showing a sheet member. [Figure 13] FIG. 13 is a top view showing a part (near the cutting insert) of the clamp structure of the cutting insert according to the modified example of this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0034] A clamping structure 10 for a cutting insert, a cutting insert 2, and an indexable cutting tool 1 according to one embodiment of the present invention will be described with reference to FIGS. 1 to 12. The indexable cutting tool 1 according to this embodiment is an indexable cutting tool used in turning, and is detachably attached to a tool post or the like of a machine tool such as a lathe (not shown). In this embodiment, the indexable cutting tool 1 may be simply referred to as a cutting tool or a tool. Furthermore, the clamping structure 10 for a cutting insert may be simply referred to as a clamping structure 10 or the like.

[0035] 1 to 4, indexable cutting tool 1 includes a clamping structure 10 for a cutting insert, a tool body 4 having an insert mounting seat 5, and a clamping member 6 that fixes clamping structure 10 for the cutting insert to insert mounting seat 5. Clamping structure 10 for the cutting insert is detachably attached to insert mounting seat 5 of tool body 4 by clamping member 6.

[0036] As shown in FIGS. 5 to 8, the clamping structure 10 for a cutting insert includes a cutting insert 2 and a supporter 3 that holds the cutting insert 2. In this embodiment, the cutting insert 2 is columnar and extends along the insert central axis C2. The supporter 3 is plate-shaped and has a pair of plate surfaces 3a, 3b that face in the direction in which the central axis C1 of the clamping structure 10 extends. The central axis C1 of the clamping structure 10 and the central axis C2 of the cutting insert 2 (insert central axis) are perpendicular to each other.

[0037] More specifically, the supporter 3 has a rectangular plate shape centered on the central axis C1, and in this embodiment, a diamond-shaped plate shape. A pair of plate surfaces 3a, 3b of the supporter 3 face opposite each other in the direction in which the central axis C1 extends. The supporter 3 also has a recessed pocket 33 disposed at one of its multiple (four in this embodiment) corners. The cutting insert 2 is disposed in the pocket 33.

[0038] The clamping structure 10 of this embodiment has roughly the same outer shape as a rectangular plate-shaped cutting insert (e.g., a V-shaped diamond insert) conforming to a general ISO standard. Therefore, the clamping structure 10 for a cutting insert of this embodiment can be mounted on an existing tool body equipped with an insert mounting seat on which a cutting insert conforming to the ISO standard is mounted.

[0039] [Direction definition] In this embodiment, an XYZ orthogonal coordinate system (three-dimensional orthogonal coordinate system) is appropriately set in each drawing, and each configuration will be described. The direction in which the central axis C1 of the clamping structure 10 for the cutting insert extends is referred to as the vertical direction. In each figure, the vertical direction corresponds to the Z-axis direction. The pair of plate surfaces 3a, 3b of the supporter 3 are arranged at different positions in the vertical direction. In the vertical direction, the direction from one plate surface 3a to the other plate surface 3b (-Z side) is referred to as the lower side, and the direction from the other plate surface 3b to the one plate surface 3a (+Z side) is referred to as the upper side. Note that the vertical direction may also be referred to as the axial direction, since it is the direction in which the central axis C1 extends. Furthermore, the vertical direction may also be referred to as the plate thickness direction, since it corresponds to the thickness direction of the plate of the supporter 3.

[0040] Among the directions perpendicular to the up-down direction, a specific direction passing through a corner where the pocket 33 of the supporter 3 is arranged and the central axis C1 is called the front-rear direction. In this embodiment, the front-rear direction also refers to a direction passing through a corner and another corner diagonally opposite the corner. In each drawing, the front-rear direction corresponds to the X-axis direction. Within the front-rear direction, the direction from the central axis C1 toward the corner (pocket 33) (-X side) is called the front side, and the direction from the corner toward the central axis C1 (+X side) is called the rear side.

[0041] The direction perpendicular to the up-down direction and the front-back direction is called the left-right direction. In each drawing, the left-right direction corresponds to the Y-axis direction. One side (+Y side) of the left-right direction is called the left side, and the other side (-Y side) is called the right side. Also, as shown in FIG. 6, in a top view (plan view) of the clamp structure 10 seen from the up-down direction, the direction approaching the insert central axis C2 of the left-right direction is called the inner side of the left-right direction, and the direction away from the insert central axis C2 is called the outer side of the left-right direction.

[0042] In this embodiment, the terms upper, lower, front, rear, left, and right are names for convenience to clearly explain the relative positional relationship of each component, and therefore the actual positional relationship when the tool is in use, etc., is not limited by these names.

[0043] The direction perpendicular to the central axis C1 of the clamp structure 10 is called the radial direction. Within the radial direction, the direction approaching the central axis C1 is called the radially inner direction, and the direction away from the central axis C1 is called the radially outer direction. The direction going around the central axis C1 is called the circumferential direction.

[0044] The central axis C1 of the clamp structure 10 is also the central axis of the supporter 3, and may therefore be referred to as the supporter central axis C1. The up-down direction (axial direction, plate thickness direction) may also be referred to as the supporter axial direction or the supporter plate thickness direction. The radial direction may also be referred to as the supporter radial direction. The circumferential direction may also be referred to as the supporter circumferential direction.

[0045] The cutting insert 2 has a central axis C2 extending in the front-rear direction. Since the front-rear direction is the direction in which the insert central axis C2 extends, it may also be referred to as the insert axial direction. The cutting insert 2 extends in the front-rear direction along the insert central axis C2.

[0046] The direction perpendicular to the insert central axis C2 is called the insert radial direction. Within the insert radial direction, the direction approaching the insert central axis C2 is called the insert radial inner direction, and the direction away from the insert central axis C2 is called the insert radial outer direction. The direction going around the insert central axis C2 is called the insert circumferential direction.

[0047] [Tool body] The tool body 4 is made of a metal such as steel. As shown in FIGS. 1 to 4, the tool body 4 is generally prismatic and extends along a central axis of the tool (not shown). The tool body 4 has a first end 4a and a second end (not shown) located at both ends in the direction in which the central axis of the tool extends. The insert mounting seat 5 of the tool body 4 is located at the first end 4a. The second end is fixed to a tool post of a machine tool or the like.

[0048] In this embodiment, the direction in which the tool central axis extends may be referred to as the tool axis direction. Furthermore, within the tool axis direction, the direction from the second end portion toward the first end portion 4a may be referred to as the tool front end side or front end side, and the direction from the first end portion 4a toward the second end portion may be referred to as the tool rear end side or rear end side.

[0049] The tool body 4 has a top surface 41 and a bottom surface 42 that face opposite each other in the up-down direction, a pair of side surfaces 43, 44 that face opposite each other in the left-right direction, and a tip surface 45 that is disposed at the first end 4a and faces the tip of the tool. The pair of side surfaces 43, 44 includes one side surface 43 and the other side surface 44. The top surface 41, the bottom surface 42, the pair of side surfaces 43, 44, and the tip surface 45 each constitute part of the outer surface of the tool body 4.

[0050] The top surface 41 faces upward. The portion of the top surface 41 located at the first end 4a of the tool body 4, i.e., the tip end, protrudes upward relative to the portion other than the first end 4a. The bottom surface 42 faces downward. In this embodiment, the tip surface 45 extends toward the right (-Y side) as it approaches the tip end of the tool.

[0051] One lateral surface 43 faces left (+Y side). The other lateral surface 44 faces right (-Y side). The portion of the other lateral surface 44 located at the first end 4a of the tool body 4 protrudes further to the right than the portion other than the first end 4a.

[0052] The tool body 4 has an insert mounting seat 5 to which the cutting insert 2 and the supporter 3 are detachably attached, and a lever accommodating portion (not shown).

[0053] The insert mounting seat 5 has a plate-shaped seat member 51. The seat member 51 is made of, for example, cemented carbide. The seat member 51 constitutes a part (bottom surface) of the insert mounting seat 5. The seat member 51 contacts the clamp structure 10 of the cutting insert from below. In other words, the seat member 51 contacts the cutting insert 2 and the supporter 3 from below, and supports the clamp structure 10 from below.

[0054] 12, in this embodiment, the sheet member 51 has a rectangular plate shape, specifically a diamond plate shape. The sheet member 51 has a sheet hole 52 that penetrates the sheet member 51 in the up-down direction, a supporter support surface 53 that is arranged on one of a pair of plate surfaces facing up (upper surface) of the sheet member 51 that faces up (upper surface), an insert support surface 54 that is arranged on the one plate surface (upper surface) and is located forward (on the -X side) of the supporter support surface 53, and a recessed portion 55 that is arranged between the supporter support surface 53 and the insert support surface 54 in the front-rear direction and is recessed downward from the one plate surface (upper surface).

[0055] The seat hole 52 has a circular hole shape centered on the central axis C1. The supporter support surface 53 has a planar shape that extends in a direction (plane direction) perpendicular to the central axis C1. The supporter support surface 53 has a generally diamond-shaped surface that is formed so that the front end portion is cut out.

[0056] The insert support surface 54 is flat. The insert support surface 54 is triangular in shape, with the left-right dimension increasing toward the rear (+X side). The insert support surface 54 extends upward toward the rear. The rear end of the insert support surface 54 is located above the supporter support surface 53. The recessed portion 55 is a groove recessed below the supporter support surface 53 and the insert support surface 54, and extends in the left-right direction.

[0057] As shown in FIGS. 1 to 4, the insert mounting seat 5 is open to the top surface 41, the other side surface 44, and the tip surface 45 at the first end 4a, i.e., the tip portion, of the tool body 4. The insert mounting seat 5 is concave and recessed from the top surface 41, the other side surface 44, and the tip surface 45 of the tool body 4. The insert mounting seat 5 has a cutout shape that can receive the clamp structure 10 of the cutting insert, i.e., the cutting insert 2 and the supporter 3. In this embodiment, the insert mounting seat 5 is a substantially quadrangular concave shape, and more specifically, a substantially diamond concave shape.

[0058] The insert mounting seat 5 has a bottom wall 5a that contacts the lower surface 21b of the insert front portion 21 of the cutting insert 2 described later and the other plate surface (lower surface) 3b of the supporter 3, and a side wall 5b that contacts the outer peripheral surface 3c of the supporter 3.

[0059] The bottom wall 5a is configured by one of the pair of plate surfaces (upper surface) of the sheet member 51 facing upward. Specifically, in this embodiment, the bottom wall 5a is configured by a supporter support surface 53 and an insert support surface 54 that are arranged on the upper surface of the sheet member 51.

[0060] A plurality of side walls 5b are provided. In this embodiment, the insert mounting seat 5 has a pair of side walls 5b. The pair of side walls 5b extend in directions that move away from each other in the left-right direction as they move toward the front side (-X side). Specifically, each side wall 5b extends outward in the left-right direction as they move toward the front side. In this embodiment, the angle formed between the pair of side walls 5b when viewed from the top-bottom direction is, for example, 35°.

[0061] Although not specifically shown, the lever housing is formed by a recess, hole, or the like disposed inside the first end 4a of the tool body 4. The lever housing houses a part of a clamp lever 61 (described later) of the clamp member 6. The lever housing extends in a radial direction (supporter radial direction) perpendicular to the central axis C1 of the clamp structure 10.

[0062] One end of the lever accommodating portion overlaps with the seat hole 52 of the seat member 51 and the through-hole 31 (described later) of the supporter 3 when viewed from the top-bottom direction. The one end of the lever accommodating portion communicates with the through-hole 31 of the supporter 3 through the seat hole 52 of the seat member 51. The other end of the lever accommodating portion is connected to a female screw hole provided in the first end 4a of the tool body 4. The other end of the lever accommodating portion communicates with the female screw hole.

[0063] [Cutting insert] The cutting insert 2 is a hard sintered body made of, for example, cemented carbide, PCD (polycrystalline diamond), cBN (cubic boron nitride), cermet, ceramic, etc. The cutting insert 2 has a higher hardness than the portions of the tool body 4 other than the seat member 51.

[0064] 5 to 8, the cutting insert 2 is detachably attached to the pocket 33 of the supporter 3. The cutting insert 2 is fixed in the pocket 33 by being clamped to the supporter 3. In this embodiment, as shown in FIG. 6, the total length dimension M of the cutting insert 2 in the front-rear direction is 2 / 3 or less of the dimension L in the front-rear direction between the center (central axis C1) of the clamp structure 10 in the front-rear direction and the front end of a cutting edge 24 (described later) of the cutting insert 2. That is, M / L≦2 / 3.

[0065] 9 and 10(a) to 10(c), the cutting insert 2 of this embodiment has a shape formed by combining two triangular pillars aligned in the direction in which the insert central axis C2 extends (front-rear direction). The dimension of the cutting insert 2 in the front-rear direction is greater than the dimension of the cutting insert 2 in the insert radial direction. Therefore, the cutting insert 2 as a whole has a pillar shape extending in the front-rear direction.

[0066] The cutting insert 2 has an insert front portion 21 arranged in a front portion of the cutting insert 2, and an insert rear portion 22 arranged in a rear portion of the cutting insert 2. The insert front portion 21 and the insert rear portion 22 are arranged adjacent to each other in the front-to-rear direction. The insert front portion 21 and the insert rear portion 22 are integrally formed by a single member.

[0067] The insert front portion 21 has a triangular prism shape. The dimension of the insert front portion 21 in the left-right direction (Y-axis direction) increases from the front end of the insert front portion 21 toward the rear side (+X side). Furthermore, the dimension of the insert front portion 21 in the up-down direction (Z-axis direction) decreases from the front end of the insert front portion 21 toward the rear side.

[0068] The insert front portion 21 has an upper surface 21a facing upward, a lower surface 21b facing downward, a pair of lateral side surfaces 21c facing left and right, a front surface 21d facing forward, and a rear end surface 21e facing rearward. The pair of lateral side surfaces 21c, the front surface 21d, and the rear end surface 21e each constitute a part of the outer peripheral surface of the insert front portion 21.

[0069] The upper surface 21a is flat. The upper surface 21a has a triangular shape with the left-right dimension increasing toward the rear. The upper surface 21a extends downward toward the rear. The upper surface 21a functions as a rake face of a cutting edge 24 (described later) of the insert front portion 21. Because the upper surface 21a is inclined with respect to the insert center axis C2 as described above, a positive (normal) rake angle is imparted to the rake face of the cutting edge 24.

[0070] The lower surface 21b is flat. The lower surface 21b has a triangular shape with the left-right dimension increasing toward the rear. The lower surface 21b extends upward toward the rear. The lower surface 21b functions as a seating surface in the cutting insert 2 that contacts (seats on) the bottom wall 5a (upper surface of the seat member 51) of the insert mounting seat 5. More specifically, when the clamp structure 10 is attached to the insert mounting seat 5 as shown in FIGS. 1 to 4, the insert support surface 54 of the seat member 51 contacts the lower surface 21b of the insert front portion 21. For this reason, the lower surface 21b may also be referred to as the insert seating surface.

[0071] As shown in FIG. 9 and FIGS. 10(a) to (c), the pair of lateral side surfaces 21c each have a planar shape. Each lateral side surface 21c has a quadrangular surface shape. Specifically, each lateral side surface 21c has a trapezoidal surface shape, and the vertical dimension decreases toward the rear side (+X side). Each lateral side surface 21c extends outward in the left-right direction toward the rear side. Specifically, of the pair of lateral side surfaces 21c, one lateral side surface 21c facing the left side (+Y side) extends toward the left as it approaches the rear side. Furthermore, of the pair of lateral side surfaces 21c, the other lateral side surface 21c facing the right side (-Y side) extends toward the right as it approaches the rear side.

[0072] The front surface 21d has a curved surface shape that protrudes forward and extends in the vertical direction. Specifically, the shape of the front surface 21d in a cross section perpendicular to the vertical direction (XY cross section) has a convex curved shape that protrudes forward. Both left and right ends of the front surface 21d and the front ends of the pair of lateral side surfaces 21c are smoothly connected without any steps. The pair of lateral side surfaces 21c and the front surface 21d function as clearance surfaces for a cutting edge 24 of the insert front portion 21, which will be described later.

[0073] The rear end surface 21e has a flat surface shape. The rear end surface 21e is located at the rear end of the insert front portion 21. In this embodiment, the rear end surface 21e has a quadrangular surface shape that extends in a direction perpendicular to the insert center axis C2 (YZ plane direction).

[0074] The insert front portion 21 also has a cutting edge 24 and a pair of rearward-facing steps 25 . The cutting edge 24 is arranged on a ridge line connecting at least the upper surface 21a of the upper surface 21a and the lower surface 21b of the insert front portion 21 to the outer circumferential surface (the pair of lateral side surfaces 21c and the front surface 21d) of the insert front portion 21, and forms a V-shape. Specifically, the cutting edge 24 forms a convex V-shape that protrudes forward.

[0075] In this embodiment, two cutting edges 24 are provided on the insert front portion 21. One of the two cutting edges 24 is located on a ridge portion where the upper surface 21a of the insert front portion 21 is connected to the outer peripheral surface, and the other is located on a ridge portion where the lower surface 21b of the insert front portion 21 is connected to the outer peripheral surface. The two cutting edges 24 of the insert front portion 21 have the same shape. Specifically, when the cutting insert 2 is rotated 180° around the insert center axis C2 (i.e., when flipped 180° up and down), the shapes of the two cutting edges 24 match. Below, the configuration of one of the two cutting edges 24 will be described in detail, and the description of the configuration of the other cutting edge 24 may be omitted.

[0076] The cutting edge 24 has a corner cutting edge portion 24a and a pair of straight cutting edges 24b. The corner cutting edge 24a is disposed on the ridge where the upper surface 21a and the front surface 21d are connected, and has a convex curved shape that bulges out toward the front side.

[0077] The pair of straight blade portions 24b are arranged on the ridge where the top surface 21a and the pair of lateral side surfaces 21c are connected. The pair of straight blade portions 24b are connected to both left and right ends of the corner blade portion 24a and extend linearly. The blade length of each straight blade portion 24b is longer than the blade length of the corner blade portion 24a. Each straight blade portion 24b is connected to the corner blade portion 24a so as to smoothly contact it without any steps.

[0078] The pair of straight blade portions 24b extend away from each other in the left-right direction as they extend rearward from the connection with the corner blade portion 24a. Specifically, each straight blade portion 24b extends outward in the left-right direction as it extends rearward.

[0079] More specifically, one of the pair of straight blade portions 24b, located to the left (+Y side) of the insert center axis C2, is located on the ridge where the top surface 21a and one of the lateral side surfaces 21c facing left are connected. One straight blade portion 24b extends leftward as it approaches the rear side.

[0080] Of the pair of straight blade portions 24b, the other straight blade portion 24b located to the right (-Y side) of the insert center axis C2 is located on the ridge line connecting the top surface 21a and the other lateral side surface 21c facing right. The other straight blade portion 24b extends toward the right as it moves toward the rear side.

[0081] In this embodiment, as shown in Figures 6 and 10(a), when viewing the clamp structure 10 or the cutting insert 2 from the top and bottom, the opening angle of the cutting edge 24, i.e., the angle θ formed between the pair of straight cutting portions 24b, is, for example, 35°.

[0082] 9 and 10(a) to 10(c), the pair of rearward-facing steps 25 are disposed on the rear end surface 21e of the insert front portion 21, facing rearward, and protrude in the left-right direction from the connection between the insert front portion 21 and the insert rear portion 22. In this embodiment, each rearward-facing step 25 has a planar shape extending in a direction perpendicular to the insert center axis C2 (YZ plane direction). Specifically, each rearward-facing step 25 has a rectangular surface extending in the up-down direction.

[0083] The insert rear portion 22 has a triangular prism shape. The insert rear portion 22 is connected to the rear end surface 21e of the insert front portion 21, and the dimension in the left-right direction (Y-axis direction) increases as it moves rearward (+X side) from the connection portion with the insert front portion 21. Furthermore, the dimension in the up-down direction (Z-axis direction) of the insert rear portion 22 decreases as it moves rearward from the connection portion with the insert front portion 21.

[0084] The insert rear portion 22 has an upper surface 22a facing upward, a lower surface 22b facing downward, a pair of insert outer surfaces 22c facing left and right, a rear surface 22d facing rearward, and a front end surface 22e facing forward.

[0085] The upper surface 22a is flat. In this embodiment, the upper surface 22a is rectangular. Specifically, the upper surface 22a is trapezoidal, and the dimension in the left-right direction increases toward the rear. The upper surface 22a also extends downward toward the rear.

[0086] The lower surface 22b has a flat surface. In this embodiment, the lower surface 22b has a quadrangular surface. Specifically, the lower surface 22b has a trapezoidal surface, and the dimension in the left-right direction increases toward the rear. The lower surface 22b also extends upward toward the rear.

[0087] Each of the pair of insert outer side surfaces 22c has a planar shape. Each insert outer side surface 22c has a triangular surface shape. Specifically, the vertical dimension of each insert outer side surface 22c decreases toward the rear side (+X side). Furthermore, each insert outer side surface 22c extends outward in the left-right direction toward the rear side. Specifically, of the pair of insert outer side surfaces 22c, one insert outer side surface 22c facing the left side (+Y side) extends toward the left as it approaches the rear side. Furthermore, of the pair of insert outer side surfaces 22c, the other insert outer side surface 22c facing the right side (-Y side) extends toward the right as it approaches the rear side.

[0088] The rear surface 22d has a curved shape that convex toward the rear and extends in the left-right direction. Specifically, the shape of the rear surface 22d in a cross section perpendicular to the left-right direction (XZ cross section) has a convex curved shape that protrudes toward the rear. Both vertical ends of the rear surface 22d are smoothly connected to the rear ends of the upper surface 22a and the lower surface 22b without any steps.

[0089] The front end surface 22e has a flat surface shape and is located at the front end of the insert rear portion 22. In this embodiment, the front end surface 22e has a quadrangular surface shape that extends in a direction perpendicular to the insert center axis C2 (YZ plane direction).

[0090] The insert rear portion 22 also has a pair of forward-facing steps 26 . The pair of forward-facing steps 26 are disposed on the front end surface 22e of the insert rear portion 22, face forward, and protrude in the vertical direction from the connection between the insert rear portion 22 and the insert front portion 21. In this embodiment, each forward-facing step 26 has a planar shape extending in a direction perpendicular to the insert center axis C2 (YZ plane direction). Specifically, each forward-facing step 26 has a rectangular surface extending in the left-right direction.

[0091] In this embodiment, the shapes of the insert front portion 21 and the insert rear portion 22 match when the cutting insert 2 is flipped 180° in the front-to-rear direction (X-axis direction) and rotated 90° around the insert center axis C2. Therefore, the cutting insert 2 of this embodiment has two cutting edges 24 on the insert front portion 21 and two cutting edges 24 on the insert rear portion 22, which is a so-called four-corner type insert shape.

[0092] 5 to 8, when the cutting insert 2 is held by the supporter 3, the cutting edge 24 located at the front portion (insert front portion 21) of the cutting insert 2 is disposed to protrude forward from the supporter 3. In addition, the rear portion (insert rear portion 22) of the cutting insert 2 is located forward from the central axis C1 of the clamp structure 10.

[0093] 1 to 4, with the cutting insert clamp structure 10 attached to the insert mounting seat 5 of the tool body 4, the lower (-Z side) of the pair of forward step portions 26 of the cutting insert 2 is inserted into the recessed portion 55 of the seat member 51. This allows the lower surface 21b of the insert front portion 21 to be well-maintained in contact with the insert support surface 54 of the seat member 51.

[0094] [Supporters] The supporter 3 is made of a metal such as steel. The supporter 3 is made of an inexpensive material that is lower in hardness and higher in toughness than the cutting insert 2. The supporter 3 is detachably attached to the insert mounting seat 5 of the tool body 4 by a clamp member 6. The supporter 3 holds the outer surface of the cutting insert 2 from the left and right directions and from the rear side.

[0095] As shown in FIGS. 5 to 8 and 11, the supporter 3 has a pair of plate surfaces 3a, 3b and an outer peripheral surface 3c. The pair of plate surfaces 3a, 3b face in the vertical direction. Of the pair of plate surfaces 3a, 3b, one plate surface (upper surface) 3a faces upward. The one plate surface 3a is flat and extends in a direction perpendicular to the central axis C1 (in the XY plane). Of the pair of plate surfaces 3a, 3b, the other plate surface (lower surface) 3b faces downward. The other plate surface 3b is flat and extends in a direction perpendicular to the central axis C1 (in the XY plane).

[0096] The lower surface 3b of the supporter 3 functions as a seating surface that contacts (seats on) the bottom wall 5a (upper surface of the seat member 51) of the insert mounting seat 5. More specifically, when the clamp structure 10 is attached to the insert mounting seat 5 as shown in FIGS. 1 to 4, the supporter support surface 53 of the seat member 51 contacts the lower surface 3b of the supporter 3. For this reason, the lower surface 3b may also be referred to as a supporter seating surface.

[0097] As shown in Figures 5 to 8 and 11, the outer peripheral surface 3c has both ends in the vertical direction connected to the upper surface 3a and the lower surface 3b. The outer peripheral surface 3c has four side surfaces 3d, 3e arranged in the circumferential direction around the central axis C1 (the supporter circumferential direction). The four side surfaces 3d, 3e are arranged on four sides of the supporter 3, which has a substantially quadrangular shape (a substantially diamond shape in this embodiment) when viewed from the vertical direction. Specifically, the outer peripheral surface 3c has a pair of front side surfaces 3d facing the front side and a pair of rear side surfaces 3e facing the rear side.

[0098] The front side surface 3d is disposed on a portion of the outer peripheral surface 3c that faces the front side and the left-right direction. The front side surface 3d is planar. The pair of front side surfaces 3d extend so as to approach each other in the left-right direction as they move toward the front side. Specifically, each front side surface 3d extends inward in the left-right direction as they move toward the front side. The pair of front side surfaces 3d are disposed side by side in the circumferential direction with a pocket 33 sandwiched between them. In other words, the pocket 33 opens between the pair of front side surfaces 3d. In this embodiment, as shown in FIG. 6, when the supporter 3 (clamp structure 10) is viewed from above and below, the angle formed between the pair of front side surfaces 3d is, for example, 35°.

[0099] The rear side surfaces 3e are disposed on a portion of the outer peripheral surface 3c that faces rearward and in the left-right direction. The pair of rear side surfaces 3e extend closer to each other in the left-right direction as they move toward the rear. Specifically, each rear side surface 3e extends inward in the left-right direction as it moves toward the rear. The pair of rear side surfaces 3e are disposed side by side in the circumferential direction. In this embodiment, the angle formed between the pair of rear side surfaces 3e in the top view shown in FIG. 6 is, for example, 35° or slightly smaller than 35°.

[0100] At least one of the pair of rear side surfaces 3e has a protruding portion 3g. In this embodiment, of the pair of rear side surfaces 3e, one of the rear side surfaces 3e located on the left side (+Y side) has the protruding portion 3g. The protruding portion 3g is located in a front portion of the one rear side surface 3e and protrudes radially outward beyond the rear portion of the one rear side surface 3e. Specifically, as shown in FIG. 6, when the supporter 3 is viewed from above and below, the protruding portion 3g protrudes outward beyond an imaginary extension line VL that extends the rear portion of the one rear side surface 3e forward.

[0101] 6, the angle formed between the other rear side surface 3e located on the right side (-Y side) and the protruding portion 3g is, for example, greater than 35°. That is, the angle formed between the other rear side surface 3e and the protruding portion 3g is greater than the angle (35°) formed between the pair of side walls 5b of the insert mounting seat 5.

[0102] The supporter 3 also has a through hole 31, a pair of arms 32, a pocket 33, and a slit 34. When the supporter 3 is viewed from above and below as shown in Fig. 6, the through hole 31, the pocket 33, and the slit 34 are located on the insert central axis C2. The pocket 33 is located in front of the through hole 31, and the slit 34 is located behind the through hole 31.

[0103] The through hole 31 penetrates the supporter 3 in the vertical direction. The through hole 31 is a circular hole that extends in the vertical direction and opens to the upper surface 3a and the lower surface 3b. The through hole 31 is located on the central axis C1 of the clamp structure 10. Specifically, the central axis of the through hole 31 is arranged coaxially with the central axis C1 of the clamp structure 10. The through hole 31 has the same inner diameter as a through hole in a rectangular plate-shaped cutting insert (e.g., a V-shaped diamond insert) that conforms to a general ISO standard.

[0104] In this embodiment, the front end of the through hole 31 and the rear end of the pocket 33 are connected to each other. That is, the through hole 31 and the pocket 33 are arranged side by side in the front-rear direction and communicate with each other. Also, the rear end of the through hole 31 and the front end of the slit 34 are connected to each other. That is, the through hole 31 and the slit 34 are arranged side by side in the front-rear direction and communicate with each other.

[0105] An upper end of a clamp lever 61 (described later) of the clamp member 6 is inserted into and locked in the through hole 31 from below the through hole 31 (see FIG. 1, etc.). That is, a part of the clamp member 6 is inserted into and locked in the through hole 31.

[0106] 5 to 8 and 11, the pair of arms 32 includes one arm 32 disposed on the left side (+Y side) of the insert central axis C2, and the other arm 32 disposed on the right side (-Y side) of the insert central axis C2. One arm 32 constitutes the left side portion of the supporter 3, and the other arm 32 constitutes the right side portion of the supporter 3.

[0107] Of each arm 32, a portion that is arranged adjacent to the through hole 31 in the left-right direction extends in a curved manner along the circumferential direction. Of each arm 32, a portion that is arranged adjacent to the pocket 33 in the left-right direction extends in the front-rear direction. Of each arm 32, a portion that is arranged adjacent to the slit 34 in the left-right direction extends in the front-rear direction. As shown in FIG. 6 , when the supporter 3 is viewed from the top-bottom direction, the portions (rear ends) of the pair of arms 32 that are arranged rearward of the slit 34 are connected to each other on the insert center axis C2.

[0108] The pair of arms 32 are movable toward each other so as to narrow the dimension of the pocket 33 in the left-right direction. In this embodiment, each of the pair of arms 32 is elastically deformable so as to narrow the dimension of the pocket 33 in the left-right direction. Specifically, one arm 32 located on the left side of the supporter 3 is capable of displacing (moving) a portion located forward of the rear end toward the right (inward in the left-right direction) due to elastic deformation. Furthermore, the other arm 32 located on the right side of the supporter 3 is capable of displacing (moving) a portion located forward of the rear end toward the left (inward in the left-right direction) due to elastic deformation.

[0109] Each arm 32 has an arm front end surface 32a that contacts the rearward step portion 25 of the insert front portion 21 of the cutting insert 2 from the rear side, and an arm inner surface 32b that contacts the insert outer surface 22c of the insert rear portion 22 from the outside in the left-right direction.

[0110] The arm front end surface 32a is located at the front end of the arm 32 and faces forward. Each arm front end surface 32a of the pair of arms 32 contacts the pair of rearward-facing steps 25 of the insert front portion 21 from the rear side. In this embodiment, each arm front end surface 32a has a flat surface extending in a direction perpendicular to the insert center axis C2 (YZ plane direction). Specifically, each arm front end surface 32a has a rectangular surface extending in the up-down direction. In this embodiment, the vertical dimension of the arm front end surface 32a is greater than the vertical dimension of the rearward-facing steps 25.

[0111] The arm inner surface 32b is located at the front end of the arm 32 and faces inward in the left-right direction (toward the insert central axis C2). In other words, the arm inner surface 32b is located at the front end of the surface of the arm 32 facing inward in the left-right direction. Each arm inner surface 32b of the pair of arms 32 contacts the pair of insert outer surfaces 22c of the insert rear portion 22 from the outside in the left-right direction.

[0112] Each of the pair of arm inner surfaces 32b has a planar shape. As shown in FIG. 11 , in this embodiment, each arm inner surface 32b has a quadrangular surface shape, specifically, a rectangular surface extending in the front-rear direction. As shown in FIG. 6 , each arm inner surface 32b extends outward in the left-right direction as it approaches the rear side (+X side). Specifically, of the pair of arm inner surface 32b, one arm inner surface 32b located to the left (+Y side) of the insert center axis C2 extends leftward as it approaches the rear side. Furthermore, of the pair of arm inner surface 32b, the other arm inner surface 32b located to the right (-Y side) of the insert center axis C2 extends rightward as it approaches the rear side.

[0113] 5 to 8 and 11, the pocket 33 is recessed from the front end of the supporter 3 to the rear. The pocket 33 opens in a wall portion facing the front of the supporter 3 and extends in the front-to-rear direction. The pocket 33 also penetrates the supporter 3 in the vertical direction and opens on the upper surface 3a and the lower surface 3b. The pocket 33 is disposed between a pair of arms 32.

[0114] The pocket 33 holds the cutting insert 2. Specifically, the insert rear portion 22 of the cutting insert 2 is disposed in the pocket 33. With the cutting insert 2 held in the pocket 33, the insert front portion 21 of the cutting insert 2 and its cutting edge 24 are disposed forward of the pocket 33.

[0115] The slits 34 penetrate the supporter 3 in the up-down direction and open to the upper surface 3a and the lower surface 3b. In this embodiment, the slits 34 extend linearly in the front-rear direction. However, this is not limiting, and the slits 34 may extend in a curved shape. The slits 34 are disposed between the pair of arms 32. By providing the slits 34, the amount of elastic deformation (amount of displacement toward the inside in the left-right direction) of each arm 32 is ensured to be greater than or equal to a predetermined amount.

[0116] [Clamping member] As shown in FIGS. 1 to 4, the clamping member 6 clamps and fixes the clamping structure 10 for the cutting insert to the insert mounting seat 5 of the tool body 4. The clamping member 6 of this embodiment has a lever lock mechanism. The clamping member 6 has a clamping lever 61 and a fastening screw (not shown). The clamping lever 61 and the fastening screw are arranged at the first end 4a of the tool body 4.

[0117] The clamp lever 61 is a member that is bent into an L-shape. Although not particularly shown, the clamp lever 61 has two extending portions (a first extending portion and a second extending portion) that extend in different directions.

[0118] The first extension portion is disposed in a lever housing portion disposed inside the first end portion 4a of the tool body 4 and extends radially. The second extension portion extends substantially in the vertical direction along the central axis C1 of the clamp structure 10. The second extension portion is disposed across one end portion of the lever housing portion, the seat hole 52 of the seat member 51, and the through hole 31 of the supporter 3. The second extension portion is inserted into the through hole 31 from below.

[0119] The fastening screw is threaded into a female threaded hole provided in the first end 4a of the tool body 4. A part of the fastening screw comes into contact with a first extension portion of the clamp lever 61. By appropriately adjusting (tightening) the amount of threading of the fastening screw into the female threaded hole, the fastening screw presses the first extension portion, and the clamp lever 61 rotates using the principle of leverage. As a result, the second extension portion of the clamp lever 61 presses the inner circumferential surface of the through hole 31 toward the rear (+X side).

[0120] When the clamp lever 61 presses the through hole 31, the supporter 3 is pulled rearward, and the rear side surfaces 3e and the protruding portions 3g of the supporter 3 are pressed against the side walls 5b of the insert mounting seat 5, causing the arms 32 to elastically deform. As a result, the pair of arms 32 move closer to each other in the left-right direction, and the cutting insert 2 is sandwiched between the pair of arms 32 and fixed in the pocket 33.

[0121] Furthermore, when the fastening screw is loosened from the female screw hole, the clamp lever 61 is released from pressing the through hole 31. When the pressure by the clamp lever 61 is released, the pressing state of the cutting insert 2 by the pair of arms 32 is also released, and the cutting insert 2 can be removed from the pocket 33.

[0122] [Effects of this embodiment] In the clamping structure 10 for a cutting insert according to the present embodiment described above, the supporter 3 holds the cutting insert 2, thereby enabling the outer dimensions of the cutting insert 2 made of an expensive hard material such as cemented carbide to be kept small. This reduces tool costs. Specifically, the clamping structure 10 for a cutting insert can reduce the amount of cemented carbide raw material used by 50% or more compared to a general cutting insert (diamond-shaped insert) conforming to ISO standards and having the same outer shape as the clamping structure 10. More specifically, the clamping structure 10 of the present embodiment can reduce the amount of raw material used for the cutting insert 2 by approximately 80% compared to a general cutting insert conforming to ISO standards.

[0123] In this embodiment, when the cutting insert clamp structure 10, i.e., the cutting insert 2 and the supporter 3, are clamped to the insert mounting seat 5 by the clamp member 6, the pair of arms 32 move toward each other to narrow the left-right dimension of the pocket 33. Specifically, the clamp member 6 is engaged with the supporter 3, and a pulling force toward the rear is applied to the supporter 3 via the clamp member 6, thereby pressing the arms 32 against the side wall 5b of the insert mounting seat 5 and elastically deforming the arms 32, thereby bringing the pair of arms 32 closer to each other. As the pair of arms 32 move toward each other, the left-right dimension (width dimension) of the pocket 33 decreases, and the cutting insert 2 is sandwiched between the pair of arms 32 and fixed in the pocket 33.

[0124] More specifically, in this embodiment, during clamping, the arm inner surfaces 32b of the pair of arms 32 contact the pair of insert outer surfaces 22c of the insert rear portion 22 of the cutting insert 2 from the outside in the left-right direction. Each insert outer surface 22c extends outward in the left-right direction as it moves toward the rear. Therefore, when the pair of arms 32 move toward each other and each arm inner surface 32b presses each insert outer surface 22c inward in the left-right direction, a pulling force that pulls the cutting insert 2 toward the rear side is generated due to the action of the wedge structure (wedge function). This allows the arm inner surfaces 32b to stably press the insert outer surface 22c.

[0125] Furthermore, the arm front end surfaces 32a of the pair of arms 32 contact, from the rear side, the pair of rearward-facing step portions 25 of the insert front portion 21 of the cutting insert 2. The wedge function described above generates a pulling force on the cutting insert 2 toward the rear side, and the contact state (pressing state) between the arm front end surfaces 32a and the rearward-facing step portions 25 is also stabilized. Therefore, according to this embodiment, the cutting insert 2 can be firmly and stably fixed by the supporter 3.

[0126] Specifically, in this embodiment, of the cutting loads (cutting resistance) acting on the cutting insert 2 during cutting, a force directed toward the rear (thrust force) can be stably received by the arm front end surface 32a of the supporter 3. Furthermore, of the cutting loads acting on the cutting insert 2, a force directed toward the left and right (feed force) can be stably received by the arm inner surface 32b utilizing the wedge function. More specifically, even if a force that rotates the cutting insert 2 in the pocket 33 due to the feed force is generated, the force can be stably received by the wedge-shaped insert outer surface 22c and arm inner surface 32b, thereby preventing unintended rotation of the cutting insert 2. Therefore, problems such as a gap occurring at the contact surface between the cutting insert 2 and the supporter 3 and misalignment of the cutting insert 2 are prevented.

[0127] Furthermore, even when a force acts to pull the cutting insert 2 forward from the pocket 33 due to relative movement with the workpiece, such as at the end of cutting, the wedge-shaped insert outer surface 22c and arm inner surface 32b can prevent the cutting insert 2 from coming out of the pocket 33.

[0128] Furthermore, the cutting insert 2 of this embodiment does not have a recess as shown in Fig. 25 of the above-mentioned Patent Document 1 (WO 2009 / 047166). Therefore, unlike conventional techniques, cracks do not occur originating from the recessed corner (neck portion) located at the rear end of the recess. Furthermore, by not providing a recess in this embodiment, the left-right dimension (width dimension) of the cutting insert 2 can be made large. Therefore, the rigidity of the cutting insert 2 is increased.

[0129] As described above, according to this embodiment, the cutting insert 2 can be made compact to reduce costs, while the cutting insert 2 can be firmly and stably held by the supporter 3 and the rigidity of the cutting insert 2 can also be ensured. In particular, in this embodiment, even if the cutting insert 2 has an opening angle (angle θ) of the V-shaped cutting edge 24 when viewed from the top and bottom (viewed from the cutting face side) as shown in Figure 6, which is small, for example, 35°, the cutting insert 2 can be firmly held by the supporter 3.

[0130] In this embodiment, the insert front portion 21 and the insert rear portion 22 have the same shape when the cutting insert 2 is turned 180° in the front-rear direction and rotated 90° around the insert central axis C2.

[0131] In this case, the cutting insert 2 has two cutting edges 24 at the insert front portion 21 and two cutting edges 24 at the insert rear portion 22, which is a so-called four-corner type insert shape. Since one cutting insert 2 is provided with a total of four cutting edges 24, the tool life of the cutting insert 2 can be extended.

[0132] In this embodiment, the rearward facing step 25 of the insert front portion 21 widens in a direction perpendicular to the insert central axis C2.

[0133] For example, unlike the above configuration, if the rearward step portion 25 extends toward the front as it moves outward in the left-right direction, when the cutting insert 2 is subjected to a cutting load (especially a thrust force) during cutting processing, the pair of arms 32 may be more likely to displace away from each other in the left-right direction (the pair of arms 32 may be more likely to open up).

[0134] In contrast, according to the above-described configuration of this embodiment, even if the cutting insert 2 receives a cutting load (especially a thrust force), the pair of arms 32 do not displace in the left-right direction so as to move away from each other (the pair of arms 32 do not become spaced apart) due to the shape of the rearward step portion 25. Therefore, the above-described effect that the cutting insert 2 can be firmly held by the supporter 3 is stably achieved.

[0135] In addition, in this embodiment, the total length dimension M of the cutting insert 2 in the front-to-back direction is 2 / 3 or less of the front-to-back direction dimension L between the front-to-back center (center axis C1) of the clamping structure 10 of the cutting insert and the front end of the cutting edge 24. In this case, the overall length M of the cutting insert 2 in the front-rear direction can be kept small, which further enhances the effect of reducing tool costs.

[0136] In addition, the indexable cutting tool 1 of this embodiment includes the above-mentioned cutting insert clamping structure 10, a tool body 4 having an insert mounting seat 5, and a clamping member 6 that fixes the cutting insert clamping structure 10 to the insert mounting seat 5. According to the indexable cutting tool 1 of this embodiment, the above-mentioned excellent effects can be obtained.

[0137] Furthermore, in the indexable cutting tool 1 of this embodiment, the insert mounting seat 5 of the tool body 4 has a seat member 51 that contacts the clamp structure 10 of the cutting insert from below. This seat member 51 has a supporter support surface 53 that contacts the lower surface 3b of the supporter 3, an insert support surface 54 that contacts the lower surface 21b of the insert front portion 21, and a recessed portion 55 that is recessed downward and disposed between the supporter support surface 53 and the insert support surface 54, into which the forward-facing step portion 26 of the insert rear portion 22 is inserted.

[0138] According to this embodiment, the seat member 51 of the insert mounting seat 5 has a recessed portion 55, and by positioning the forward-facing step portion 26 on the lower side of the insert rear portion 22 within the recessed portion 55, the contact state between the lower surface 3b of the supporter 3 and the supporter support surface 53 can be stabilized, and the contact state between the lower surface 21b of the insert front portion 21 and the insert support surface 54 can be stabilized.

[0139] That is, the clamp structure 10 of the cutting insert can be stably supported from below by the seat member 51. Therefore, the seat member 51 can stably receive the downward force (principal force) of the cutting load (cutting resistance) acting on the cutting insert 2 during cutting.

[0140] Furthermore, according to the cutting insert 2 of this embodiment, the same excellent effects as those of the clamping structure 10 of the cutting insert described above can be obtained.

[0141] [Other configurations included in the present invention] The present invention is not limited to the above-described embodiment, and the configuration may be modified within the scope of the present invention, as described below. In the illustrations of the modified examples, the same components as those in the above-described embodiment are denoted by the same reference numerals, and the following mainly describes the differences.

[0142] FIG. 13 is a top view of a portion (near the cutting insert 2) of the clamp structure 20 for a cutting insert according to a modification of the embodiment described above, viewed from the top-bottom direction. In this modification, a pair of rearward-facing steps 25 provided on the insert front portion 21 of the cutting insert 2 each extend toward the rear (+X side) as they move outward in the left-right direction. Also in this modification, the insert front portion 21 and the insert rear portion 22 have the same shape when the cutting insert 2 is flipped 180° in the front-to-back direction and rotated 90° around the insert center axis C2. Therefore, of the pair of forward-facing steps 26 provided on the insert rear portion 22, the forward-facing step 26 located on the upper side (+Z side) extends toward the front (-X side) as it moves upward. Furthermore, of the pair of forward-facing steps 26, the forward-facing step 26 located on the lower side (-Z side) extends toward the front as it moves downward.

[0143] In this modified example, the arm front end surfaces 32a of the pair of arms 32 extend rearward (toward the +X side) as they move outward in the left-right direction. According to the above modification, even if the cutting insert 2 receives a cutting load (especially a thrust force) during cutting, the pair of arms 32 will not be displaced apart in the left-right direction (the pair of arms 32 will not be spaced apart) due to the shape of the rearward step 25. Therefore, the effect of being able to firmly hold the cutting insert 2 by the supporter 3 is stably achieved.

[0144] In the above-described embodiment, the angle (opening angle) θ formed between the pair of linear cutting portions 24b of the cutting edge 24 of the cutting insert 2, the angle formed between the pair of front side surfaces 3d of the supporter 3, the angle formed between the pair of rear side surfaces 3e of the supporter 3, and the angle formed between the pair of side walls 5b of the insert mounting seat 5 are each 35° when viewed from the top and bottom. However, this is not limited to this. Although not specifically illustrated, each of the above angles may be, for example, 55°, 60°, 80°, 90°, etc. Furthermore, while the example has been described in which the overall shape of the clamping structures 10, 20 for the cutting insert is a rectangular plate shape such as a diamond plate shape, this is not limited to this, and the clamping structures may be, for example, a triangular plate shape. In any of the above cases, as in the above-described embodiment, the product of the present invention can be mounted on existing indexable cutting tools and their tool bodies equipped with various cutting inserts conforming to ISO standards.

[0145] In the above-described embodiment, the clamp member 6 has a lever lock mechanism, but this is not limiting. Although not particularly shown, the clamp member 6 may have a clamp piece and a clamp screw.

[0146] In this case, the clamp piece is disposed on the first end 4a of the top surface 41 of the tool body 4. The front end of the clamp piece is located above the insert mounting seat 5 and contacts the upper surface 3a of the supporter 3. The clamp piece has a screw insertion hole that passes through the clamp piece in the vertical direction, and a protrusion that is disposed at the front end of the clamp piece and protrudes downward from the underside of the clamp piece. The protrusion is inserted into the through hole 31 of the supporter 3 from above.

[0147] The clamp screw is inserted from above into the screw insertion hole of the clamp piece and threaded into a threaded hole opening in the top surface 41 of the tool body 4. As the clamp screw is threaded into the threaded hole, the clamp piece moves downward and is retracted rearward. As a result, the protrusion of the clamp piece engages with the inner peripheral surface of the through hole 31, retracting the supporter 3 rearward, and the pair of arms 32 clamp the cutting insert 2 from the left and right. Additionally, the portion of the underside of the front end of the clamp piece that is located around the protrusion comes into contact with the upper surface 3a of the supporter 3 from above, pressing the supporter 3 downward. In this way, the clamp structure 10, 20 for the cutting insert is fixed to the insert mounting seat 5. As described above, even when the clamp member 6 is configured to include a clamp piece and a clamp screw, the same excellent effects as those of the above-described embodiment can be obtained.

[0148] 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]

[0149] The clamping structure for a cutting insert, the indexable cutting tool, and the cutting insert of the present invention enable the cutting insert to be compact and reduce costs, while the supporter can firmly and stably hold the cutting insert and ensure the rigidity of the cutting insert, and therefore have industrial applicability. [Explanation of symbols]

[0150] 1...Indexable cutting tools 2...Cutting insert 3...Supporters 4...Tool body 5...Insert mounting seat 6...Clamping member 10, 20...Cutting insert clamping structure 21...Front of insert 21a…Top surface 21b…Bottom surface 21e…Rear end surface 22...Rear part of insert 22c...Outer surface of insert 22e...front end surface 24...Cutting edge 25...Backward facing step 26...Forward stepped section 32...Arm 32a...Front end face of arm 32b...Inner surface of arm 33...Pocket 51...Sheet member 53...Supporter support surface 54...Insert support surface 55...Theft Department C1…Central axis C2: Insert center axis L: The distance between the center of the clamping structure of the cutting insert and the front end of the cutting edge in the front-to-back direction M... Overall length of cutting insert in the front-to-rear direction

Claims

1. A clamping structure for a cutting insert that is detachably attached to an insert mounting seat of a tool body by a clamping member, a cutting insert extending in the front-rear direction along a central axis of the insert; a supporter for holding the cutting insert; The cutting insert comprises: a front portion of the insert whose left-right dimension increases from the front end toward the rear; an insert rear portion connected to a rear end surface of the insert front portion, the dimension of which in the left-right direction increases from the connection portion with the insert front portion toward the rear side, The insert front portion is a V-shaped cutting edge disposed on a ridge line connecting at least the upper surface of the upper and lower surfaces of the insert front portion to the outer circumferential surface; a pair of rearward-facing step portions disposed on a rear end surface of the insert front portion, facing rearward, and protruding in the left-right direction from a connection portion between the insert front portion and the insert rear portion; the insert rear portion has a pair of insert outer surfaces facing in the left-right direction, Each insert outer surface extends outward in the left-right direction toward the rear, The supporter is a pocket having a recessed shape recessed from a front end portion of the supporter to a rear side, in which the cutting insert is disposed; a pair of arms that can move toward each other so as to narrow the left-right dimension of the pocket; The cutting edge of the cutting insert is disposed forward of the pocket, Each of the arms is a front end surface of the arm that contacts the rearward facing step portion from the rear side; and an arm inner surface that contacts the insert outer surface from the outside in the left-right direction. Cutting insert clamping structure.

2. Two cutting edges are provided at the front portion of the insert, one of the two cutting edges is disposed on a ridge portion where the upper surface and the outer peripheral surface of the insert front portion are connected, and the other is disposed on a ridge portion where the lower surface and the outer peripheral surface of the insert front portion are connected, the insert front portion and the insert rear portion have shapes that match each other when the cutting insert is turned over 180° in the front-rear direction and rotated 90° around the insert central axis; The clamping structure of the cutting insert according to claim 1 .

3. The rearward step portion extends in a direction perpendicular to the insert central axis or extends rearward as it extends outward in the left-right direction. The clamping structure of the cutting insert according to claim 1 .

4. The total length of the cutting insert in the front-to-rear direction is 2 / 3 or less of the dimension in the front-to-rear direction between the center of the clamp structure of the cutting insert in the front-to-rear direction and the front end of the cutting edge. The clamping structure of the cutting insert according to claim 1 .

5. The clamping structure for a cutting insert according to any one of claims 1 to 4; the tool body having the insert mounting seat; the clamping member that fixes the clamping structure of the cutting insert to the insert mounting seat, Indexable cutting tool.

6. The clamping structure for a cutting insert according to claim 2; the tool body having the insert mounting seat; the clamping member that fixes the clamping structure of the cutting insert to the insert mounting seat, the rear insert portion has a pair of forward-facing step portions that are disposed on a front end surface of the rear insert portion, face forward, and protrude in the up-down direction from a connection portion between the rear insert portion and the front insert portion; the insert mounting seat has a seat member that contacts the clamp structure of the cutting insert from below, The sheet member is a supporter support surface that contacts the lower surface of the supporter; an insert support surface contacting the underside of the insert front portion; a recessed portion disposed between the supporter support surface and the insert support surface, recessed downward, into which the forward step portion is inserted; Indexable cutting tool.

7. A cutting insert extending in the front-rear direction along the insert central axis, a front portion of the insert whose left-right dimension increases from the front end toward the rear; an insert rear portion connected to a rear end surface of the insert front portion, the dimension of which in the left-right direction increases from the connection portion with the insert front portion toward the rear side, The insert front portion is a V-shaped cutting edge disposed on a ridge line connecting at least the upper surface of the upper and lower surfaces of the insert front portion to the outer circumferential surface; a pair of rearward-facing step portions disposed on a rear end surface of the insert front portion, facing rearward, and protruding in the left-right direction from a connection portion between the insert front portion and the insert rear portion; the insert rear portion has a pair of insert outer surfaces facing in the left-right direction, Each insert outer surface extends outward in the left-right direction as it moves toward the rear side. Cutting insert.

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