Cutting insert clamping structure and indexable cutting tool

Abstract

To provide a clamp structure of a cutting insert and a cutting edge replaceable cutting tool, capable of firmly and stably holding the cutting insert by a supporter, and capable of restraining positional dislocation of the cutting insert in cutting work, while reducing cost by compacting the cutting insert.SOLUTION: The supporter (3) includes a pair of arms (32) movable toward each other so as to narrow a size of the pocket (33) in a left-right direction, and a pair of convex portions (35) protruding downward from the pair of arms (32) and insertable from a front side into a concave portion (53) opened in a bottom wall 5a of the insert mounting seat. A distance in the left-right direction between a pair of outer side surfaces 35a of each projection 35 facing outward in the left-right direction is larger than a distance in the left-right direction between a pair of inner side surfaces of each recess 53 facing inward in the left-right direction.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a clamping structure for a cutting insert and an indexable cutting tool. [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 to stably hold the miniaturized cutting insert with the supporter. If the cutting insert cannot be firmly and stably held by the supporter, the cutting insert may become misaligned when subjected to cutting load during cutting, which may affect machining accuracy.

[0005] The present invention aims to provide a cutting insert clamping structure and an indexable cutting tool that can make the cutting insert compact and reduce costs, while firmly and stably holding the cutting insert with a supporter and preventing the cutting insert from shifting position during cutting processing. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides the following means.

[0007] [Aspect 1 of the present invention] A clamping structure for a cutting insert that is removably attached to an insert mounting seat arranged on a tool body by a clamping member, comprising: a cutting insert having a cutting edge arranged at at least a front end; and a supporter that holds the cutting insert, wherein the supporter is concave and recessed rearward from the front end of the supporter, and has a pocket in which the cutting insert is arranged, a pair of arms that can move toward each other so as to narrow the left-right dimension of the pocket, and a pair of protrusions that protrude downward from the pair of arms and can be inserted from the front into a recess that opens into a bottom wall of the insert mounting seat, wherein the left-right dimension between a pair of outer surfaces facing outward in the left-right direction of each of the protrusions is greater than the left-right dimension between a pair of inner surfaces facing inward in the left-right direction of the recess.

[0008] 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, for example, about 80% compared to a general cutting insert that conforms to ISO standards and has the same outer shape as this clamping structure.

[0009] In the present invention, when the cutting insert is clamped, that is, when the cutting insert and the supporter are attached to the insert mounting seat by the clamp member, the pair of arms move toward each other so as to narrow the left-right dimension of the pocket.

[0010] Specifically, the clamping member is engaged with the supporter, and a pulling force toward the rear is applied to the supporter via the clamping member, causing the pair of protrusions to move rearward together with the supporter. At this time, the pair of protrusions are inserted from the front into recesses that open in the bottom wall of the insert mounting seat. In this invention, the left-right dimension between the pair of outer surfaces facing outward in the left-right direction of each protrusion is larger than the left-right dimension between the pair of inner surfaces facing inward in the left-right direction of the recess. Therefore, the pair of protrusions are guided by the recesses while moving rearward, and move closer to each other in the left-right direction.

[0011] When the pair of protrusions are moved closer to each other in the left-right direction so as to reduce the distance between them, the pair of arms connected to the pair of protrusions also move closer to each other in the left-right direction, causing the cutting insert to be sandwiched and clamped between the pair of arms (i.e., in the pocket). The present invention has a special configuration in which a pair of arms are moved closer together via a pair of protrusions guided by a recess in the insert mounting seat, thereby generating a strong clamping force at a position close to the cutting insert.

[0012] More specifically, if the rear ends of the pair of arms are considered as fulcrums, the front ends of the pair of arms (the portions that clamp the cutting insert) are considered as points of application, and the pair of protrusions that move the pair of arms toward each other in the left-right direction are considered as points of application of force, it is possible to set the distance from the fulcrum to the point of application and the distance from the fulcrum to the point of application to be approximately the same. In other words, compared to conventional cutting insert clamping structures, the product of the present invention allows the point of application of force to be sufficiently close to the point of application. This significantly increases the insert fastening force, and reduces problems such as the cutting insert becoming misaligned even when subjected to cutting loads during cutting.

[0013] As described above, according to the present invention, the cutting insert can be made compact to reduce costs, and the supporter can firmly and stably hold the cutting insert, preventing the cutting insert from shifting position during cutting, thereby stably improving the accuracy of cutting.

[0014] [Aspect 2 of the present invention] The clamping structure for a cutting insert according to aspect 1, further comprising a seat member constituting a bottom wall of the insert mounting seat, wherein the recess opens at least to a front-facing surface and an upper surface of the seat member.

[0015] In this case, by using the seat member of the present invention instead of the seat member provided in the insert mounting seat of a conventional cutting tool, the excellent effects of the present invention described above can be obtained. That is, the clamping structure of the cutting insert of this embodiment can be applied to the tool body of an existing indexable cutting tool in which a cutting insert conforming to a general ISO standard is mounted in the insert mounting seat, thereby increasing versatility.

[0016] [Embodiment 3 of the present invention] A clamping structure for a cutting insert according to aspect 2, wherein the hardness of the seat member is higher than the hardness of the supporter.

[0017] In this case, the seat member is made of, for example, cemented carbide, and the supporter is made of, for example, steel. Because the hardness of the seat member is greater than that of the supporter, when the pair of protrusions of the supporter are guided by the recesses of the seat member, the pair of arms are stably displaced in the left-right direction together with the pair of protrusions. In other words, the left-right dimension between the pair of inner surfaces facing inward in the left-right direction of the recess is maintained constant without expanding during clamping, so the above-mentioned effects of the present invention are stably achieved.

[0018] [Aspect 4 of the present invention] A clamping structure of a cutting insert described in any one of aspects 1 to 3, wherein the outer surface of the convex portion has an outer inclined surface located at at least the rear end of the outer surface, and the outer inclined surface extends inward in the left-right direction as it moves toward the rear side.

[0019] In this case, since the outer inclined surface is provided on the outer surface of the convex portion, the outer inclined surface makes it easier for the convex portion to enter the concave portion from the front-rear direction.

[0020] [Embodiment 5 of the present invention] A clamping structure of a cutting insert described in any one of aspects 1 to 4, wherein the inner surface of the recess has an inner inclined surface located at at least the front end of the inner surface, and the inner inclined surface extends outward in the left-right direction as it moves toward the front side.

[0021] In this case, since the inner inclined surface is provided on the inner surface of the recess, the inner inclined surface makes it easier for the protrusion to enter the recess from the front-rear direction.

[0022] [Aspect 6 of the present invention] A clamping structure for a cutting insert described in any one of aspects 1 to 5, wherein the cutting edge has a V-shape that is convex toward the front when viewed from above, and the opening angle of the cutting edge when viewed from above is 55° or less.

[0023] When the opening angle of the V-shaped cutting edge of the cutting insert is 55° or less, it is also difficult to ensure the thickness of the pair of arms of the supporter. Therefore, with the above opening angle, it is more difficult for the conventional clamping structure of the cutting insert to firmly hold the cutting insert with the pair of arms.

[0024] In contrast, according to the present invention, even when the opening angle of the cutting blades is small, at 55° or less, and it is difficult to ensure the thickness of the arms, the clamping force of the pair of arms can be stably increased by the action of the pair of protrusions. Therefore, when the opening angle of the cutting blades is 55° or less, the effects of the present invention are particularly remarkable.

[0025] [Embodiment 7 of the present invention] 7. The clamping structure for a cutting insert according to any one of aspects 1 to 6, wherein the supporter has a vertically inverted symmetrical shape.

[0026] In this case, the supporter has a pair of protrusions protruding downward from the pair of arms, as well as another pair of protrusions protruding upward from the pair of arms. Therefore, when the pair of protruding downwards wears out due to repeated friction with the recesses of the sheet member made of a hard material, the supporter can be turned upside down and reattached to the insert mounting seat, allowing the other pair of unused protrusions to be inserted into the recesses to clamp the cutting insert. This extends the component life of the supporter.

[0027] [Embodiment 8 of the present invention] Aspect 8. The clamping structure for a cutting insert according to any one of aspects 1 to 7, wherein the recess has a pair of grooves into which the pair of protrusions are inserted, and the grooves are bottomed grooves.

[0028] In this case, the rigidity of the sheet member in the vicinity of the recessed portion is increased, so that the above-described effects of the present invention are more stably achieved.

[0029] [Embodiment 9 of the present invention] An indexable cutting tool comprising: the clamping structure for a cutting insert according to any one of aspects 1 to 8; the tool body; and the clamping member that fixes the clamping structure for the cutting insert to the insert mounting seat. [Effects of the Invention]

[0030] According to the above-described aspects of the cutting insert clamping structure and indexable cutting tool 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, thereby preventing the cutting insert from shifting position during cutting processing. [Brief explanation of the drawings]

[0031] [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 the cutting insert and a part of the indexable cutting tool according to the present embodiment. [Figure 3] FIG. 3 is a side view showing a clamping structure of the cutting insert and a part of the indexable cutting tool according to the present embodiment. [Figure 4] FIG. 4 is a front view showing the clamping structure of the cutting insert and the indexable cutting tool of the present embodiment. [Figure 5] FIG. 5 is a perspective view showing the clamping structure of the cutting insert of the present embodiment. [Figure 6] FIG. 6 is a top view showing the clamping structure of the cutting insert of this embodiment. [Figure 7] FIG. 7 is a side view showing the clamping structure of the cutting insert of this embodiment. [Figure 8] FIG. 8 is a front view showing the clamping structure of the cutting insert of this embodiment. [Figure 9] FIG. 9 is a perspective view showing a cutting insert. [Figure 10] FIG. 10 is a top view showing the cutting insert. [Figure 11] FIG. 11 is a perspective view showing a supporter. [Figure 12] FIG. 12 is a side view showing the supporter. [Figure 13] FIG. 13 is a front view showing the supporter. [Figure 14] FIG. 14 is a bottom view showing the supporter. [Figure 15] FIG. 15 is a perspective view showing a sheet member. [Figure 16] FIG. 16 is a top view showing the sheet member. [Figure 17] FIG. 17 is a side view showing the sheet member. [Figure 18] FIG. 18 is a bottom view showing a part of the supporter of the first modified example of this embodiment. [Figure 19] FIG. 19 is a top view showing a part of a sheet member according to a second modified example of the present embodiment. [Figure 20] FIG. 20 is a perspective view showing a supporter according to a third modified example of the present embodiment. [Figure 21] FIG. 21 is a perspective view showing a sheet member according to a fourth modified example of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0032] A clamping structure 10 for a cutting insert and an indexable cutting tool 1 according to one embodiment of the present invention will be described with reference to FIGS. 1 to 17. 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.

[0033] 1 to 4, indexable cutting tool 1 includes a clamping structure 10 for a cutting insert, a tool body 4, and a clamping member 6 that fixes clamping structure 10 for a cutting insert to an insert mounting seat 5 arranged on tool body 4. Clamping structure 10 for a cutting insert is detachably mounted to insert mounting seat 5 by clamping member 6.

[0034] 5 to 8, the clamp structure 10 for a cutting insert includes a cutting insert 2, a supporter 3 that holds the cutting insert 2, and a seat member 51 that forms part of the insert mounting seat 5. FIGS. 5 to 8 show the cutting insert 2, the supporter 3, and the seat member 51 combined together.

[0035] The supporter 3 is plate-shaped and has a pair of plate surfaces 3a, 3b facing in the direction in which the central axis C1 of the clamp structure 10 extends. More specifically, the supporter 3 is a quadrangular plate centered on the central axis C1, and in this embodiment, is a diamond-shaped plate. The 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 concave pocket 33 arranged in one of its multiple (four in this embodiment) corners. The cutting insert 2 is arranged in the pocket 33.

[0036] 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) and a seat member that conform 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 that has an insert mounting seat on which a cutting insert conforming to the ISO standard is mounted.

[0037] [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. Specifically, the central axis C1 corresponds to the central axis of the supporter 3. In each drawing, 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 thickness direction, since it corresponds to the thickness direction of the plate-shaped supporter 3.

[0038] 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.

[0039] 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 of the left-right direction (+Y side) is called the left side, and the other side (-Y side) is called the right side. The +Y side corresponds to the left side when the clamp structure 10 of the cutting insert is viewed from the front (-X side) as shown in FIG. 8, and the -Y side corresponds to the right side when the clamp structure 10 of the cutting insert is viewed from the front.

[0040] 6, in a top view of the clamp structure 10 seen from above (+Z side) along the up-down direction, the direction approaching the central axis C1 in the left-right direction is called the inner side in the left-right direction, and the direction away from the central axis C1 is called the outer side in the left-right direction. More specifically, in the top view shown in FIG. 6, when an imaginary line passing through the central axis C1 and extending in the front-to-rear direction is defined as a reference line R, the inner side in the left-right direction is a direction approaching the reference line R in the left-right direction, and the outer side in the left-right direction is a direction away from the reference line R in the left-to-right direction. Specifically, the outer side in the left-to-right direction is a direction from the reference line R to the left (+Y side) or right (-Y side).

[0041] 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.

[0042] The direction perpendicular to the central axis C1 is called the radial direction. Of the radial directions, 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.

[0043] 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 vertical direction (axial direction, plate thickness direction) may also be referred to as the supporter axial 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.

[0044] The direction in which the insert central axis C2 of the cutting insert 2 extends is referred to as the insert axial direction. The insert central axis C2 of the cutting insert 2 is located forward of the central axis C1 of the supporter 3 and extends parallel to the central axis C1. In other words, the insert axial direction corresponds to the up-and-down direction, the axial direction, the plate thickness direction, and the supporter axial direction.

[0045] The insert central axis C2 and the central axis C1 of the supporter 3 are located at the same position in the left-right direction. Therefore, in the top view shown in Fig. 6, a reference line R that passes through the central axis C1 and extends in the front-rear direction passes through 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] 15 to 17, the direction in which the seat central axis C3, which is the central axis of the seat member 51, extends is referred to as the seat axial direction. As shown in Fig. 6, the seat central axis C3 of the seat member 51 is located slightly rearward of the central axis C1 of the supporter 3 and extends parallel to the central axis C1. In other words, the seat axial direction corresponds to the up-and-down direction, the axial direction, the plate thickness direction, the insert axial direction, and the supporter axial direction. 6. Similarly to the center axis C1 and the insert center axis C2, the seat center axis C3 is also located on the reference line R in the top view shown in FIG.

[0048] The direction perpendicular to the seat central axis C3 is called the seat radial direction. Within the seat radial direction, the direction approaching the seat central axis C3 is called the inner seat radial direction, and the direction away from the seat central axis C3 is called the outer seat radial direction. The direction going around the seat central axis C3 is called the seat circumferential direction.

[0049] [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 of the tool body 4 is fixed to a tool post of a machine tool or the like.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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). In this embodiment, a part of the insert mounting seat 5 (a bottom wall 5a described later) is configured by a seat member 51 of the clamp structure 10. The seat member 51 will be described separately later.

[0055] 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. In this embodiment, the insert mounting seat 5 is a substantially quadrangular concave shape, and more specifically, a substantially diamond concave shape.

[0056] The insert mounting seat 5 has a bottom wall 5a in contact with the lower surface 22 of the cutting insert 2 and the other plate surface (lower surface) 3b of the supporter 3, and a side wall 5b in contact with the outer peripheral surface 3c of the supporter 3.

[0057] In this embodiment, the bottom wall 5a is formed of a sheet member 51. Specifically, the bottom wall 5a is formed of one of a pair of plate surfaces of the plate-shaped sheet member 51, the plate surface facing upward (upper surface). The side wall 5b is formed of the tool body 4.

[0058] 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°.

[0059] 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.

[0060] One end of the lever accommodating portion overlaps with a seat hole 52 (described later) of the seat member 51 and a through hole 31 (described later) of the supporter 3 when viewed from the top-bottom direction. 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.

[0061] [Cutting insert] The cutting insert 2 is made of, for example, cemented carbide, PCD (polycrystalline diamond), cBN (cubic boron nitride), cermet, ceramic, etc. The cutting insert 2 is a hard sintered body having a higher hardness than the tool body 4.

[0062] 5 to 8, the cutting insert 2 is detachably attached to the pocket 33 of the supporter 3. The cutting insert 2 is fixed to the pocket 33 by being clamped to the supporter 3.

[0063] 9 and 10, the cutting insert 2 of this embodiment has a columnar shape centered on the insert central axis C2, specifically, a substantially polygonal columnar shape. The dimension of the cutting insert 2 in the front-rear direction is larger than the dimension of the cutting insert 2 in the left-right direction. That is, the cutting insert 2 extends in the front-rear direction. In this embodiment, the dimension of the cutting insert 2 in the up-down direction (height dimension) is larger than the dimension of the cutting insert 2 in the left-right direction (width dimension) and is smaller than the dimension of the cutting insert 2 in the front-rear direction (total length dimension).

[0064] The cutting insert 2 has an upper surface 21 and a lower surface 22 facing in the vertical direction, an outer peripheral surface 23 connected to the upper surface 21 and the lower surface 22, and a cutting edge 24 arranged on the ridge portion where at least the upper surface 21 and the outer peripheral surface 23 are connected.

[0065] The upper surface 21 has a generally polygonal shape that is long in the front-to-rear direction. The upper surface 21 faces upward. The upper surface 21 has a rake face 26. The rake face 26 is located at the end of the upper surface 21 in the front-to-rear direction. The rake face 26 is located at a portion of the upper surface 21 that is adjacent to the cutting edge 24. The rake face 26 is connected to the cutting edge 24.

[0066] The lower surface 22 has a generally polygonal shape that is long in the front-to-rear direction. The lower surface 22 faces downward. The lower surface 22 has a seating surface 27. The seating surface 27 is flat and extends in a direction perpendicular to the insert central axis C2. The seating surface 27 comes into contact with the bottom wall 5a of the insert mounting seat 5, i.e., the upper surface of the seat member 51.

[0067] The outer peripheral surface 23 faces outward in the insert radial direction and extends in the insert circumferential direction. The outer peripheral surface 23 has a flank 28. The flank 28 is located at an end of the outer peripheral surface 23 in the insert axial direction. The flank 28 is located at a portion of the outer peripheral surface 23 adjacent to the cutting edge 24. The flank 28 is connected to the cutting edge 24.

[0068] The outer peripheral surface 23 has a front wall 23a that is located at the front end of the outer peripheral surface 23 and faces forward, a rear wall 23b that is located at the rear end of the outer peripheral surface 23 and faces rearward, a lateral wall 23c that is located between the front wall 23a and the rear wall 23b in the front-to-rear direction and faces left-to-right, a rearward-facing step 23d that is located between the front wall 23a and the lateral wall 23c and faces rearward, and a forward-facing step 23e that is located between the rear wall 23b and the lateral wall 23c and faces forward.

[0069] The front wall 23a is a wall surface located inward in the left-right direction as it extends toward the front (-X side). The front wall 23a has a flat surface facing forward and outward in the left-right direction. A pair of front walls 23a are provided on the outer circumferential surface 23.

[0070] As shown in Figure 10, when viewed from above (+Z side) of the cutting insert 2, if a virtual straight line passing through the insert center axis C2 and extending in the front-to-back direction is defined as a reference line R, one of the pair of front walls 23a is located on the left side (+Y side) of the reference line R and faces forward and left, and the other front wall 23a is located on the right side (-Y side) of the reference line R and faces forward and right.

[0071] The dimension (distance) in the left-right direction between the pair of front walls 23a becomes smaller toward the front. In this embodiment, a convex curved surface portion that is convex toward the front is disposed between the front ends of the pair of front walls 23a.

[0072] The rear wall 23b is a wall surface that is positioned inward in the left-right direction as it extends toward the rear (+X side). The rear wall 23b has a flat surface that faces rearward and outward in the left-right direction. A pair of rear walls 23b are provided on the outer peripheral surface 23.

[0073] In the top view of the cutting insert 2 shown in Figure 10, one of the pair of rear side walls 23b is located on the left side (+Y side) of the reference line R and faces rearward and leftward, and the other rear side wall 23b is located on the right side (-Y side) of the reference line R and faces rearward and rightward.

[0074] The dimension (distance) in the left-right direction between the pair of rear side walls 23b becomes smaller toward the rear. In this embodiment, a convex curved surface portion that is convex toward the rear is disposed between the rear end portions of the pair of rear side walls 23b.

[0075] The lateral side wall 23c is a wall surface located in an intermediate portion of the outer peripheral surface 23 between the front end and the rear end. The lateral side wall 23c has a planar shape that extends in a direction perpendicular to the left-right direction. In this embodiment, the lateral side wall 23c extends in the front-rear direction. The front-rear dimension of the lateral side wall 23c is larger than the front-rear dimension of the front wall 23a and larger than the front-rear dimension of the rear wall 23b.

[0076] A pair of lateral side walls 23c are provided on the outer peripheral surface 23. The pair of lateral side walls 23c face opposite each other in the left-right direction. One of the pair of lateral side walls 23c is located on the left side (+Y side) of the reference line R and faces left, and the other lateral side wall 23c is located on the right side (-Y side) of the reference line R and faces right.

[0077] The rearward step 23d is connected to the rear end of the front wall 23a and the front end of the lateral wall 23c. The rearward step 23d is a wall surface that is positioned inward in the left-right direction as it extends toward the rear (+X side). The rearward step 23d is flat and faces rearward and outward in the left-right direction. A pair of rearward step portions 23d are provided on the outer circumferential surface 23.

[0078] 10, one of the pair of rearward step portions 23d is disposed on the left side (+Y side) of the reference line R and faces rearward and leftward, and the other rearward step portion 23d is disposed on the right side (-Y side) of the reference line R and faces rearward and rightward. The dimension (distance) in the left-right direction between the pair of rearward step portions 23d becomes smaller toward the rear side.

[0079] The forward step 23e is connected to the front end of the rear side wall 23b and the rear end of the lateral side wall 23c. The forward step 23e is a wall surface that is positioned inward in the left-right direction as it extends toward the front (-X side). The forward step 23e is flat and faces forward and outward in the left-right direction. A pair of forward step portions 23e are provided on the outer circumferential surface 23.

[0080] 10, one of the pair of forward-facing step portions 23e is disposed on the left side (+Y side) of the reference line R and faces forward and left, and the other forward-facing step portion 23e is disposed on the right side (-Y side) of the reference line R and faces forward and right. The dimension (distance) in the left-right direction between the pair of forward-facing step portions 23e decreases toward the front.

[0081] The cutting edge 24 is disposed at least at the front end of the cutting insert 2. As shown in Fig. 9, the cutting edge 24 is disposed on a ridge portion where the rake face 26 and the flank 28 are connected. The cutting edge 24 has a V-shape that is convex toward the front side (-X side) in a top view of the cutting insert 2 shown in Fig. 10. The cutting edge 24 has a corner cutting portion 24a and a straight cutting portion 24b.

[0082] The corner cutting edge 24a has a convex curved shape that bulges forward. The straight cutting edge 24b is connected to an end of the corner cutting edge 24a and extends linearly. The cutting edge length of the straight cutting edge 24b is longer than the cutting edge length of the corner cutting edge 24a. In this embodiment, a pair of straight cutting edges 24b is connected to both ends of the corner cutting edge 24a in the cutting edge length direction. That is, a pair of straight cutting edges 24b is provided on the cutting edge 24. In this embodiment, the angle θ formed between the pair of straight cutting edges 24b in the top view shown in FIG. 10, i.e., the opening angle θ in the top view of the cutting edge 24, is, for example, 35°.

[0083] In this embodiment, the cutting insert 2 has a shape that is inverted and symmetrical in the insert axial direction, i.e., the up-down direction. That is, the cutting insert 2 has a shape that is inverted and symmetrical in the up-down direction. The cutting insert 2 also has a shape that is inverted and symmetrical in the front-to-back direction. That is, the cutting insert 2 has a shape that is 180° rotationally symmetrical about the insert central axis C2.

[0084] Moreover, when viewed from the top-bottom direction, the cutting insert 2 has a left-right symmetrical (line symmetrical) shape with the reference line R as the axis of symmetry. Moreover, when viewed from the top-bottom direction, the cutting insert 2 has a front-back symmetrical (line symmetrical) shape with the imaginary line V as the axis of symmetry that passes through the insert center axis C2 and is perpendicular to the reference line R.

[0085] For this reason, a plurality of cutting edges 24 are provided on the cutting insert 2. Specifically, a total of four cutting edges 24 are provided: two at both ends of the upper surface 21 in the front-rear direction and two at both ends of the lower surface 22 in the front-rear direction.

[0086] 5 to 8, when the cutting insert 2 is held by the supporter 3, the cutting edge 24 located at the front end of the cutting insert 2 is disposed to protrude forward from the supporter 3. In addition, the rear end of the cutting insert 2 is disposed forward from the central axis C1 of the supporter 3.

[0087] [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. As shown in FIGS. 1 to 4, the supporter 3 is detachably attached to the insert mounting seat 5 by a clamp member 6. The supporter 3 holds the outer peripheral surface 23 of the cutting insert 2 from at least the outer side in the left-right direction and the rear side. In this embodiment, the supporter 3 also holds a portion of the outer peripheral surface 23 of the cutting insert 2 (the forward-facing step portion 23e) from the front side.

[0088] As shown in Figures 5 to 8 and 11 to 14, 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 up and down. 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. 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.

[0089] 7, in this embodiment, the upper surface 21 of the cutting insert 2 is disposed at the same position as one plate surface 3a in the vertical direction, i.e., flush with the upper surface 3a of the supporter 3. The lower surface 22 of the cutting insert 2 is disposed at the same position as the other plate surface 3b in the vertical direction, i.e., flush with the lower surface 3b of the supporter 3. Specifically, the seating surface 27 of the cutting insert 2 and the lower surface 3b of the supporter 3 are disposed flush with each other. The seating surface 27 and the lower surface 3 b come into contact with the bottom wall 5 a of the insert mounting seat 5 , that is, the upper surface of the seat member 51 .

[0090] As shown in Figures 5 to 8 and 11 to 14, both ends of the outer peripheral surface 3c in the vertical direction are connected to the pair of plate surfaces 3a, 3b. The outer peripheral surface 3c has four side surfaces 3d, 3e aligned in the circumferential direction (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 (-X side) and a pair of rear side surfaces 3e facing the rear side (+X side).

[0091] The front side surface 3d is located at the front portion of the outer peripheral surface 3c. The front side surface 3d extends inward in the left-right direction as it approaches the front. The front side surface 3d is flat and faces forward and outward in the left-right direction.

[0092] As shown in Figure 6, when the supporter 3 is viewed from above (+Z side), if a virtual straight line passing through the central axis C1 and extending in the front-to-back direction is defined as a reference line R, one of the pair of front side surfaces 3d is located on the left side (+Y side) of the reference line R and faces forward and left, and the other front side surface 3d is located on the right side (-Y side) of the reference line R and faces forward and right.

[0093] The dimension (distance) in the left-right direction between the pair of front side surfaces 3d decreases toward the front. A pocket 33 opens between the front end portions of the pair of front side surfaces 3d. In this embodiment, the angle formed between the pair of front side surfaces 3d in the top view shown in FIG. 6 is, for example, 35°. Note that this angle is the same as the opening angle θ of the cutting edge 24 in the top view.

[0094] The rear side surface 3e is located on the rear portion of the outer peripheral surface 3c. The rear side surface 3e extends inward in the left-right direction as it approaches the rear. The rear side surface 3e is flat and faces rearward and outward in the left-right direction.

[0095] As shown in Figure 6, when viewed from above (+Z side) the supporter 3, one of the pair of rear side surfaces 3e is located on the left side (+Y side) of the reference line R and faces rearward and leftward, and the other rear side surface 3e is located on the right side (-Y side) of the reference line R and faces rearward and rightward.

[0096] The dimension (distance) in the left-right direction between the pair of rear side surfaces 3e decreases toward the rear. A convex curved surface portion that is convex toward the rear is disposed between the rear end portions of the pair of rear side surfaces 3e. 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°. Note that this angle is the same as the angle formed between the pair of side walls 5b of the insert mounting seat 5 in the top view of the tool body 4 (see FIG. 2).

[0097] The outer peripheral surface 3c of the supporter 3 (the front side surface 3d and the rear side surface 3e except for the protrusions 37 described later) has the same outer shape as a rectangular plate-shaped cutting insert (diamond-shaped insert) conforming to a general ISO standard. In Fig. 6, the outer shape of the diamond-shaped insert conforming to the ISO standard is indicated by the symbol I (two-dot chain line).

[0098] 5 to 8 and 11 to 14, the supporter 3 has a through hole 31, a pair of arms 32, a pocket 33, a slit 34, a pair of protrusions 35, and a plurality of protrusions 37. 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 a reference line R. The pocket 33 is located in front of the through hole 31, and the slit 34 is located behind the through hole 31.

[0099] The through hole 31 penetrates the supporter 3 in the vertical direction. The through hole 31 is a substantially circular hole that extends in the vertical direction and opens to the pair of plate surfaces 3a, 3b. The through hole 31 is located on the central axis C1 of the supporter 3. Specifically, the central axis of the through hole 31 is arranged coaxially with the central axis C1 of the supporter 3. The through hole 31 of the supporter 3 has the same inner diameter as the through hole of a rectangular plate-shaped cutting insert (diamond insert) that conforms to a general ISO standard.

[0100] 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.

[0101] 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.

[0102] 6, the pair of arms 32 includes one arm 32 disposed on the left side (+Y side) of the reference line R, and the other arm 32 disposed on the right side (-Y side) of the reference line R. One arm 32 constitutes at least the front portion of the left side of the supporter 3, and the other arm 32 constitutes at least the front portion of the right side of the supporter 3. In this embodiment, one arm 32 constitutes substantially the entire left side of the supporter 3, and the other arm 32 constitutes substantially the entire right side of the supporter 3.

[0103] The portion of each arm 32 that is disposed adjacent to the through hole 31 in the left-right direction extends in a curved manner along the circumferential direction. The portion of each arm 32 that is positioned adjacent to the pocket 33 in the left-right direction extends in the front-rear direction. Specifically, the portion of each arm 32 that is positioned outside the pocket 33 in the left-right direction extends inward in the left-right direction as it moves forward.

[0104] The portion of each arm 32 that is positioned adjacent to the slit 34 in the left-right direction extends in the front-rear direction. Specifically, the portion of each arm 32 that is positioned outside the slit 34 in the left-right direction extends inward in the left-right direction as it extends toward the rear. 6, when the supporter 3 is viewed from above and below, the portions (rear ends) of the pair of arms 32 that are located rearward of the slits 34 are connected to each other on the reference line R.

[0105] 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 its 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 its rear end toward the left (inward in the left-right direction) due to elastic deformation.

[0106] As shown in Figures 6, 11 and 14, each arm 32 has a first locking surface 32a that contacts the rearward step portion 23d of the cutting insert 2, a second locking surface 32b that contacts the lateral side wall 23c of the cutting insert 2, a third locking surface 32c that contacts the rearward side wall 23b of the cutting insert 2, and a fourth locking surface 32d that contacts the forward step portion 23e of the cutting insert 2.

[0107] The first locking surface 32a, the second locking surface 32b, the third locking surface 32c, and the fourth locking surface 32d are arranged in the pocket 33. The first locking surface 32a, the second locking surface 32b, the third locking surface 32c, and the fourth locking surface 32d are locked to parts of the outer peripheral surface 23 of the cutting insert 2, respectively.

[0108] The first locking surface 32a is disposed on the front end surface of the arm 32 and faces the front side (-X side). In the top view shown in FIG. 6, the first locking surface 32a extends toward the front side as it moves outward in the left-right direction. The first locking surface 32a has a flat shape that faces the front side and inward in the left-right direction. The first locking surface 32a comes into contact with the rearward-facing step portion 23d of the cutting insert 2 from the rear side (+X side).

[0109] The second locking surface 32b is located at the front end of the arm 32 and faces inward in the left-right direction. The second locking surface 32b is located rearward of the first locking surface 32a and adjacent to the first locking surface 32a. The second locking surface 32b extends in the front-rear direction. The second locking surface 32b is flat and extends in a plane direction perpendicular to the left-right direction (XZ plane direction). The second locking surface 32b contacts the lateral side wall 23c of the cutting insert 2 from the outside in the left-right direction.

[0110] The third locking surface 32c is located rearward of the second locking surface 32b. In the top view shown in FIG. 6, the third locking surface 32c extends inward in the left-right direction toward the rear. The third locking surface 32c has a flat shape facing inward in the left-right direction and toward the front. The third locking surface 32c contacts the rear wall 23b of the cutting insert 2 from the outer side in the left-right direction and from the rear side.

[0111] The fourth locking surface 32d is disposed between the second locking surface 32b and the third locking surface 32c. The fourth locking surface 32d is connected to the rear end of the second locking surface 32b and the front end of the third locking surface 32c. In the top view shown in FIG. 6, the fourth locking surface 32d extends rearward as it moves outward in the left-right direction. The fourth locking surface 32d has a flat shape facing rearward and inward in the left-right direction. The fourth locking surface 32d contacts the forward-facing step portion 23e of the cutting insert 2 from the front side.

[0112] 5, 6, 11, and 14, 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 of the supporter 3. The pocket 33 is disposed between a pair of arms 32.

[0113] The pocket 33 holds the cutting insert 2. Specifically, a portion of the cutting insert 2 other than the front end portion is disposed in the pocket 33. With the cutting insert 2 held in the pocket 33, the front end portion of the cutting insert 2 and its cutting edge 24 are disposed to protrude forward from the pocket 33.

[0114] The pocket 33 restrains the outer peripheral surface 23 of the cutting insert 2 from both outer sides in the left-right direction and from the front and rear sides. The restraining surfaces of the pocket 33 that restrain the cutting insert 2 are composed of the first locking surfaces 32a, the second locking surfaces 32b, the third locking surfaces 32c, and the fourth locking surfaces 32d of the pair of arms 32.

[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 of the supporter 3. In this embodiment, the slits 34 extend linearly in the front-rear direction in the top view shown in FIG. 6. However, this is not limiting, and the slits 34 may extend in a curved shape in this top view. The slits 34 are disposed between the pair of arms 32. By providing the slits 34, the amount of elastic deformation of each arm 32 (the amount of displacement toward the inside in the left-right direction) is ensured to be equal to or greater than a predetermined dimension.

[0116] As shown in Figures 5, 7, 8 and 11 to 14, the pair of protrusions 35 protrude downward from the pair of arms 32. Specifically, each protrusion 35 protrudes downward from the front end of each arm 32. That is, each protrusion 35 protrudes downward from the lower surface 3b of the supporter 3. Each protrusion 35 also extends in the front-rear direction. In this embodiment, each protrusion 35 is rib-shaped. Each protrusion 35 has a larger dimension in the front-rear direction (total length) than its dimension in the left-right direction (width).

[0117] As shown in Fig. 14, in a bottom view of the supporter 3 seen from the bottom (-Z side), the front end surface of the protrusion 35 is located at the same position as the front end surface of the arm 32. More specifically, as shown in Figs. 11 and 13, the front end surface of the protrusion 35 is located below the first locking surface 32a of the arm 32 and is continuous with the first locking surface 32a. The front end surface of the protrusion 35 and the first locking surface 32a each form a part of a single continuous plane.

[0118] In a bottom view of the supporter 3 shown in Fig. 14, the end face of the protrusion 35 facing inward in the left-right direction is located at the same position as the end face of the front end of the arm 32 facing inward in the left-right direction. More specifically, as shown in Figs. 11 and 13, the end face of the protrusion 35 facing inward in the left-right direction is located below the second locking surface 32b of the arm 32 and is continuous with the second locking surface 32b. The end face of the protrusion 35 facing inward in the left-right direction and the second locking surface 32b each form part of a single, continuous plane.

[0119] 14, the rear end surface of the protrusion 35 is disposed forward of the third locking surface 32c of the arm 32. In this embodiment, the rear end surface of the protrusion 35 is disposed forward of the fourth locking surface 32d of the arm 32. In the illustrated example, the rear end surface of the protrusion 35 has a flat shape that extends in a plane direction (YZ plane direction) perpendicular to the front-rear direction.

[0120] In the bottom view of the supporter 3 shown in Fig. 14, the front end of the end face of the protrusion 35 facing outward in the left-right direction is located at the same position as the front side surface 3d of the arm 32. More specifically, as shown in Figs. 11 and 13, the front end of the end face of the protrusion 35 facing outward in the left-right direction is located below the front side surface 3d and is continuous with the front side surface 3d. The front end of the end face of the protrusion 35 facing outward in the left-right direction and the front side surface 3d each form part of a single continuous plane.

[0121] 14, each protrusion 35 has an outer surface 35a facing outward in the left-right direction. That is, a pair of protrusions 35 has a pair of outer surfaces 35a facing opposite each other in the left-right direction (both outer surfaces in the left-right direction). One of the pair of outer surfaces 35a faces left (+Y side), and the other outer surface 35a faces right (-Y side).

[0122] The outer side surface 35a is disposed on the end surface of the protrusion 35 facing outward in the left-right direction, other than the front end portion. The outer side surface 35a is located more inward in the left-right direction than the front side surface 3d. In the bottom view shown in FIG. 14, each outer side surface 35a has a linear shape extending in the front-to-rear direction. Each outer side surface 35a has a planar shape extending in a plane direction (XZ plane direction) perpendicular to the left-to-right direction.

[0123] 6, 11, and 14, the multiple protrusions 37 are arranged on the outer peripheral surface 3c of the supporter 3. Specifically, each protrusion 37 is arranged on the rear side surface 3e of the supporter 3. Each protrusion 37 comes into contact with the side wall 5b when the clamp structure 10 is attached to the insert mounting seat 5 (see FIG. 2). The multiple protrusions 37 include a first protrusion 37A and a second protrusion 37B that is arranged rearward of the first protrusion 37A.

[0124] The first protrusion 37A is disposed at the front end of the rear side surface 3e of the supporter 3. The first protrusion 37A protrudes radially outward from the rear side surface 3e other than the protrusion 37. That is, the first protrusion 37A protrudes from the outer peripheral surface 3c of the supporter 3. More specifically, the first protrusion 37A protrudes radially outward from the outer shape I of the diamond-shaped insert conforming to the ISO standard shown in FIG. 6. The first protrusion 37A forms a convex curve when viewed from the top-bottom direction.

[0125] A pair of first protrusions 37A are provided on the supporter 3. The pair of first protrusions 37A are arranged on each side surface (rear side surface 3e) facing radially outward of the pair of arms 32. In this embodiment, the four corners of the supporter 3 include a pair of acute-angled corners and a pair of obtuse-angled corners, and the pair of first protrusions 37A are arranged at the pair of obtuse-angled corners.

[0126] The second protrusion 37B is disposed rearward of the first protrusion 37A with a gap therebetween. The second protrusion 37B is disposed in a middle portion between the front end and the rear end of the rear side surface 3e of the supporter 3. The second protrusion 37B protrudes radially outward from the rear side surface 3e other than the protrusion 37. That is, the second protrusion 37B protrudes from the outer peripheral surface 3c of the supporter 3. More specifically, the second protrusion 37B protrudes radially outward from the outer shape I of the diamond-shaped insert conforming to the ISO standard shown in FIG. 6. The second protrusion 37B forms a convex curve when viewed from the top-bottom direction.

[0127] A pair of second protrusions 37B are provided on the supporter 3. The pair of second protrusions 37B are arranged on each side surface (rear side surface 3e) facing radially outward of the pair of arms 32. The pair of second protrusions 37B are arranged between a pair of obtuse-angled corners of the supporter 3 and one acute-angled corner located at the rear end of the supporter 3.

[0128] The amount by which the first protrusions 37A protrude from the outer peripheral surface 3c (rear side surface 3e) of the supporter 3 is greater than the amount by which the second protrusions 37B protrude from the outer peripheral surface 3c (rear side surface 3e). As shown in Fig. 6, when viewed from the top-bottom direction, the radius of curvature of the first protrusions 37A is greater than the radius of curvature of the second protrusions 37B. The circumferential dimension of the first protrusions 37A is greater than the circumferential dimension of the second protrusions 37B.

[0129] [Sheet member] As shown in FIGS. 15 to 17, the sheet member 51 has a plate shape. In this embodiment, the sheet member 51 has a rectangular plate shape, and more specifically, a substantially diamond-shaped plate shape. A pair of plate surfaces of the sheet member 51 face in the vertical direction. Of the pair of plate surfaces of the sheet member 51, one plate surface (upper surface) facing upward is flat and extends in a plane direction (XY plane direction) perpendicular to the vertical direction. Furthermore, the other plate surface (lower surface) facing downward of the sheet member 51 is flat and extends in a plane direction perpendicular to the vertical direction. As shown in FIGS. 1, 3, and 4, one plate surface (upper surface) of the sheet member 51 forms the bottom wall 5a of the insert mounting seat 5. In this embodiment, the upper surface of the sheet member 51 may be referred to as the bottom wall 5a.

[0130] 5, 7, and 8, the sheet member 51 contacts the cutting insert 2 and the supporter 3 from below. Specifically, the upper surface of the sheet member 51, i.e., the bottom wall 5a, contacts the lower surface 22 of the cutting insert 2 and the lower surface 3b of the supporter. The sheet member 51 supports the cutting insert 2 and the supporter 3 from below. The vertical dimension of the sheet member 51 (i.e., the plate thickness dimension) is greater than the vertical dimension of each of the pair of protrusions 35 of the supporter 3 (i.e., the amount of protrusion that each protrusion 35 protrudes downward from the lower surface 3b of the supporter 3).

[0131] The seat member 51 is made of a hard material that is harder than the tool body 4, and specifically, is made of, for example, cemented carbide. By making the seat member 51 of a high-hardness material, wear of the bottom wall 5a (insert seating surface) of the insert mounting seat 5 is prevented. Also, if the cutting insert 2 is broken, damage to the insert seating surface is prevented. The hardness of the seat member 51 is also higher than that of the supporter 3.

[0132] As shown in FIGS. 15 to 17, the sheet member 51 has a sheet hole 52, a recess 53, and a protrusion support portion .

[0133] The seat hole 52 penetrates the seat member 51 in the vertical direction. The seat hole 52 opens on the upper and lower surfaces of the seat member 51. The seat hole 52 has a multi-stage circular hole shape centered on the seat central axis C3. In this embodiment, the inner diameter of an upper hole portion of the seat hole 52 that opens on the upper surface of the seat member 51 is larger than the inner diameter of a lower hole portion of the seat hole 52 that opens on the lower surface of the seat member 51.

[0134] The recess 53 opens to the bottom wall 5a of the insert mounting seat 5. Specifically, the recess 53 opens to at least the surface facing the front and the upper surface (bottom wall 5a) of the seat member 51. In this embodiment, the recess 53 opens to the upper surface, lower surface, and the front end portion (the surface facing the front) of the outer peripheral surface of the seat member 51.

[0135] The recess 53 has a pair of grooves 55. The pair of grooves 55 are arranged in the recess 53 at a distance from each other in the left-right direction. Each groove 55 extends in the front-rear direction. Each groove 55 opens at the upper surface (bottom wall 5a), the lower surface, and the front end portion (the surface facing the front) of the outer peripheral surface of the sheet member 51. That is, the groove 55 in this embodiment is a slit-shaped groove that penetrates the sheet member 51 in the up-down direction.

[0136] As shown in Figure 16, when the seat member 51 is viewed from above (+Z side), if a virtual straight line passing through the seat center axis C3 and extending in the fore-and-aft direction is defined as a reference line R, one of the pair of grooves 55 is located on the left side (+Y side) of the reference line R, and the other groove 55 is located on the right side (-Y side) of the reference line R.

[0137] Each groove 55 has a first groove wall 55a disposed at an inner end of the groove 55 in the left-right direction and facing outward in the left-right direction, a second groove wall 55b disposed at a rear end of the groove 55 and facing forward, and an inner side surface 53a disposed at an outer end of the groove 55 in the left-right direction and facing inward in the left-right direction. That is, the recess 53 has a pair of inner side surfaces 53a facing inward in the left-right direction.

[0138] The first groove wall 55a is a plane extending in a plane direction perpendicular to the left-right direction (XZ plane direction). The second groove wall 55b is a plane extending in a plane direction perpendicular to the front-rear direction (YZ plane direction). The inner surface 53a is a plane extending in a plane direction perpendicular to the left-right direction.

[0139] When the clamp structure 10 is attached to the insert mounting seat 5, the pair of protrusions 35 of the supporter 3 are inserted from the front into the pair of grooves 55 of the seat member 51. That is, the pair of protrusions 35 can be inserted from the front into the recess 53 that opens into the bottom wall 5a of the insert mounting seat 5. For this reason, the left-right dimension of each groove 55 (groove width dimension) is larger than the left-right dimension of each protrusion 35 (rib width dimension). Also, in FIG. 5 and other figures, when the supporter 3 is attached to the seat member 51, the second groove wall 55b of each groove 55 is located rearward of the rear end surface of each protrusion 35.

[0140] 14 and 16, the left-right dimension L1 between a pair of outer surfaces 35a facing outward in the left-right direction of each protrusion 35 is larger than the left-right dimension L2 between a pair of inner surfaces 53a facing inward in the left-right direction of the recess 53. Therefore, when the clamp structure 10 is attached to the insert mounting seat 5, when each protrusion 35 is inserted into each groove 55, each protrusion 35 is displaced (moved) inward in the left-right direction while being guided by each groove 55. As a result, the pair of arms 32 are displaced inward in the left-right direction together with the pair of protrusions 35, and the left-right dimension of the pocket 33 is narrowed (reduced).

[0141] The protruding support portion 54 is disposed between the pair of grooves 55 and protrudes forward from each groove 55. The protruding support portion 54 has a columnar shape extending in the front-rear direction. At least a portion of the lower surface 22 of the cutting insert 2 contacts the upper surface of the protruding support portion 54. That is, the protruding support portion 54 supports the cutting insert 2 from below.

[0142] 7, the front end of the protruding support portion 54 is located rearward of the cutting edge 24 located at the front end of the cutting insert 2. In addition, as shown in FIG. 8, the left-right dimension (width dimension) of the protruding support portion 54 is smaller than the left-right dimension of the cutting insert 2.

[0143] [Clamping member] As shown in Figures 1 and 2, 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.

[0144] The clamp lever 61 is a member that is bent into an L shape. Although not specifically shown, the clamp lever 61 has two extensions (a first extension and a second extension) that extend in different directions. The first extension and the second extension are connected to each other, so that the clamp lever 61 has an L shape as a whole.

[0145] 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.

[0146] 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).

[0147] When the clamp lever 61 presses the through hole 31, the supporter 3 is pulled rearward relative to the insert mounting seat 5 (the pair of side walls 5b and the seat member 51 (bottom wall 5a)). As a result, the rear side surfaces 3e of the supporter 3 are pressed against the side walls 5b, causing the arm 32 to elastically deform. In this embodiment, the pair of protrusions 35 of the supporter 3 are inserted into the pair of grooves 55 (recesses 53), causing the arm 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.

[0148] In this embodiment, when the supporter 3 is pulled rearward by the clamp member 6, the pair of first protrusions 37A are pressed against the pair of side walls 5b of the insert mounting seat 5, causing elastic deformation of the arms 32. In addition, in the process of elastic deformation of the pair of arms 32, the pair of second protrusions 37B are also pressed against the pair of side walls 5b.

[0149] Furthermore, when the fastening screw is loosened from the female screw hole, the clamp lever 61 is released from pressing the through hole 31. By releasing the pressure from the clamp lever 61, the pair of arms 32 can also release the pressure from the cutting insert 2, and the cutting insert 2 can be removed from the pocket 33.

[0150] [Effects of this embodiment] In the clamping structure 10 for a cutting insert of this embodiment described above, the supporter 3 holds the cutting insert 2, which allows 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, in the clamping structure 10 for a cutting insert of this embodiment, the amount of cemented carbide raw material used can be reduced by, for example, about 80% compared to a general cutting insert (diamond-shaped insert) conforming to ISO standards and having the same outer shape as this clamping structure 10.

[0151] In this embodiment, when clamping the cutting insert clamping structure 10, i.e., when the cutting insert 2 and the supporter 3 are attached to the insert mounting seat 5 by the clamping member 6, the pair of arms 32 move toward each other so as to narrow the left-right dimension of the pocket 33.

[0152] 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, causing the pair of protrusions 35 to move rearward together with the supporter 3. At this time, the pair of protrusions 35 are inserted from the front into the recess 53 that opens in the bottom wall 5a of the insert mounting seat 5. In this embodiment, the left-right dimension L1 between the pair of outer side surfaces 35a facing outward in the left-right direction of each protrusion 35 is larger than the left-right dimension L2 between the pair of inner side surfaces 53a facing inward in the left-right direction of the recess 53. Therefore, the pair of protrusions 35 are guided by the recess 53 while moving rearward, and move closer to each other in the left-right direction.

[0153] When the pair of protrusions 35 are moved closer to each other in the left-right direction so as to reduce the distance between them, the pair of arms 32 connected to the pair of protrusions 35 also move closer to each other in the left-right direction. As a result, the cutting insert 2 is sandwiched and clamped between the pair of arms 32 (i.e., in the pocket 33). In this embodiment, a special configuration is provided in which a pair of arms 32 are moved closer to each other via a pair of protrusions 35 guided by the recesses 53 of the insert mounting seat 5, thereby generating a strong clamping force at a position close to the cutting insert 2.

[0154] More specifically, for example, if the rear ends of the pair of arms 32 are considered as fulcrums, the front ends of the pair of arms 32 (portions that clamp the cutting insert 2) are considered as points of application, and the pair of protrusions 35 that move the pair of arms 32 toward each other in the left-right direction are considered as points of application of force, it is possible to set the distance from the fulcrum to the point of application and the distance from the fulcrum to the point of application to be approximately the same. In other words, compared to the clamping structure of conventional cutting inserts, the product of the present invention allows the point of application of force to be sufficiently close to the point of application. This significantly increases the insert fastening force, and prevents problems such as the cutting insert 2 shifting position even when subjected to cutting loads during cutting.

[0155] As described above, according to this embodiment, the cutting insert 2 can be made compact to reduce costs, and the cutting insert 2 can be firmly and stably held by the supporter 3, which can prevent the cutting insert 2 from shifting position during cutting. Therefore, the accuracy of cutting can be stably improved.

[0156] In this embodiment, the clamping structure 10 for the cutting insert further includes a seat member 51 that forms the bottom wall 5a of the insert mounting seat 5, and the recess 53 opens at least on the front-facing surface and the top surface of the seat member 51.

[0157] In this case, by using the seat member 51 of the present invention instead of the seat member provided in the insert mounting seat of a conventional cutting tool, the excellent effects of the present embodiment described above can be obtained. That is, the cutting insert clamp structure 10 of the present embodiment can be applied to the tool body of an existing indexable cutting tool in which a cutting insert conforming to a general ISO standard is mounted in an insert mounting seat, thereby increasing versatility.

[0158] In this embodiment, the hardness of the sheet member 51 is higher than the hardness of the supporter 3. Specifically, in this embodiment, the sheet member 51 is made of, for example, cemented carbide, and the supporter 3 is made of, for example, steel. Because the hardness of the sheet member 51 is set higher than the hardness of the supporter 3, when the pair of protrusions 35 of the supporter 3 are guided by the recesses 53 of the sheet member 51, the pair of arms 32 are stably displaced in the left-right direction together with the pair of protrusions 35. In other words, the dimension L2 in the left-right direction between the pair of inner surfaces 53a facing inward in the left-right direction of the recesses 53 is maintained constant without widening during clamping, and the effects of this embodiment described above are stably achieved.

[0159] [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.

[0160] FIG. 18 is a bottom view showing a part of the supporter 3 of the first modified example of the clamp structure 10 for the cutting insert of the embodiment described above. 18, in the supporter 3 of the first modified example, the outer side surface 35a of the protrusion 35 facing outward in the left-right direction has an outer inclined surface 35b arranged at least at the rear end of the outer side surface 35a. In the bottom view shown in FIG. 18, the outer inclined surface 35b extends inward in the left-right direction as it approaches the rear side (+X side).

[0161] In this case, since the outer inclined surface 35b is provided on the outer side surface 35a of the protrusion 35, the outer inclined surface 35b makes it easier for the protrusion 35 to enter the recess 53 (groove 55) from the front-rear direction.

[0162] FIG. 19 is a top view showing a part of a seat member 51 of a second modified example of the clamp structure 10 for a cutting insert of the embodiment described above. 19, in the sheet member 51 of the second modification, the inner side surface 53a facing inward in the left-right direction of the recess 53 has an inner inclined surface 53b disposed at least at the front end of the inner side surface 53a. In the top view shown in FIG. 19, the inner inclined surface 53b extends outward in the left-right direction as it approaches the front side (-X side).

[0163] In this case, since the inner inclined surface 53b is provided on the inner side surface 53a of the recess 53, the inner inclined surface 53b makes it easier for the protrusion 35 to enter the recess 53 (groove 55) from the front-rear direction.

[0164] FIG. 20 is a perspective view showing a supporter 3 of a third modified example of the clamp structure 10 for a cutting insert of the above-described embodiment. As shown in FIG. 20, the supporter 3 of the third modified example has a shape that is symmetrical when viewed from the top and bottom (a shape that is symmetrical when viewed from the front and back).

[0165] In this case, the supporter 3 has a pair of protrusions 35 protruding downward (-Z side) from the pair of arms 32, as well as another pair of protrusions 35 protruding upward (+Z side) from the pair of arms 32. Therefore, when the pair of protrusions 35 protruding downward are worn due to repeated friction with the recessed portions 53 of the sheet member 51 made of a hard material, the supporter 3 can be turned upside down and reattached to the insert mounting seat 5, so that the other pair of unused protrusions 35 can be inserted into the recessed portions 53 to clamp the cutting insert 2. This extends the component life of the supporter 3.

[0166] FIG. 21 is a perspective view showing a seat member 51 of a fourth modified example of the clamp structure 10 for a cutting insert of the embodiment described above. 21, in the sheet member 51 of the fourth modification, each of the pair of grooves 55 in the recess 53 is a bottomed groove. That is, the grooves 55 are open to the surface facing the front of the sheet member 51 (the front end portion of the outer circumferential surface) and the upper surface (bottom wall 5a), but are not open to the lower surface.

[0167] In this case, the rigidity of the sheet member 51 in the vicinity of the recess 53 is increased, so that the above-described effects of this embodiment are more stably achieved.

[0168] In the above-described embodiment, the angle θ formed between the pair of linear cutting portions 24b of the cutting edge 24 of the cutting insert 2 (opening angle of the cutting edge 24), 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 all 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 structure 10 for the cutting insert is a rectangular plate shape such as a diamond plate shape, this is not limited to this, and the clamping structure 10 may also 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.

[0169] It is more preferable that the opening angle θ of the cutting edge 24 in a top view is 55° or less. When the opening angle θ of the V-shaped cutting edge 24 of the cutting insert 2 is 55° or less, it is also likely to be difficult to ensure the thickness of the pair of arms 32 of the supporter 3. For this reason, when the opening angle θ is as described above, it is more difficult for the conventional clamping structure of the cutting insert to firmly hold the cutting insert with the pair of arms.

[0170] In contrast, according to the present invention, even when the opening angle θ of the cutting blade 24 is small, at 55° or less, and it is difficult to ensure the thickness of the arms 32, the clamping force of the pair of arms 32 can be stably increased by the action of the pair of protrusions 35. Therefore, when the opening angle θ of the cutting blade 24 is 55° or less, the operational effect of the present invention becomes particularly remarkable.

[0171] In the above embodiment, the supporter 3 has a plurality of protrusions 37 (37A, 37B), but the present invention is not limited to this. Furthermore, although an example has been given in which the supporter 3 has the slits 34, the present invention is not limited to this, and the slits 34 may not be provided.

[0172] In the above-described embodiment, an example was given in which the clamping structure 10 for the cutting insert includes the seat member 51, but this is not limited thereto. For example, the seat member 51 may not be provided on the insert mounting seat 5, and a recess 53 recessed downward from the bottom wall (insert seating surface) of the insert mounting seat 5 formed on the tool body 4 may be directly provided on this bottom wall. However, as explained in the above-described embodiment, it is more preferable to provide the seat member 51 separately from the tool body 4, as this reduces wear and damage to the tool body 4.

[0173] 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.

[0174] 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.

[0175] 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 circumferential 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. Furthermore, the portion of the underside of the front end of the clamp piece that is located around the protrusion contacts the upper surface 3a of the supporter 3 from above, pressing the supporter 3 downward. In this way, the clamp structure 10 for the cutting insert is fixed to the insert mounting seat 5. In this case, the seat member 51 is fixed to the tool body 4 by screws or the like. 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.

[0176] 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]

[0177] The clamping structure for a cutting insert and the indexable cutting tool of the present invention can reduce the cost by making the cutting insert compact, while the supporter can firmly and stably hold the cutting insert, preventing the cutting insert from shifting during cutting. This allows for stable improvement in cutting accuracy. Therefore, the present invention has industrial applicability. [Explanation of symbols]

[0178] 1...Indexable cutting tools 2...Cutting insert 3...Supporters 4...Tool body 5...Insert mounting seat 5a…Bottom wall 6...Clamping member 10...Cutting insert clamping structure 24...Cutting edge 32...Arm 33...Pocket 35...Convex part 35a…Outer surface 35b…Outside slope 51...Sheet member 53...recess 53a...Inner surface 53b…Inner slope 55...Groove L1, L2...Dimensions θ: Opening angle of the cutting edge as viewed from above

Claims

1. A clamping structure for a cutting insert that is detachably attached to an insert mounting seat disposed on a tool body by a clamping member, a cutting insert having a cutting edge disposed at least at a front end thereof; a supporter for holding the cutting insert; 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 movable toward each other so as to narrow the left-right dimension of the pocket; a pair of protrusions that protrude downward from the pair of arms and that can be inserted from the front into a recess that opens into a bottom wall of the insert mounting seat, a left-right dimension between a pair of outer surfaces of each of the protrusions facing outward in the left-right direction is larger than a left-right dimension between a pair of inner surfaces of each of the recesses facing inward in the left-right direction; Cutting insert clamping structure.

2. The insert mounting seat further includes a sheet member that forms a bottom wall of the insert mounting seat. The recessed portion is open at least on a surface facing the front side and an upper surface of the sheet member. The clamping structure of the cutting insert according to claim 1 .

3. The hardness of the sheet member is higher than the hardness of the supporter. The clamping structure for a cutting insert according to claim 2 .

4. the outer surface of the protrusion has an outer inclined surface disposed at least at a rear end portion of the outer surface, The outer inclined surface extends inward in the left-right direction as it moves toward the rear side. The clamping structure for a cutting insert according to any one of claims 1 to 3.

5. The inner surface of the recess has an inner inclined surface disposed at least at a front end portion of the inner surface, The inner inclined surface extends outward in the left-right direction as it moves forward. The clamping structure for a cutting insert according to any one of claims 1 to 3.

6. The cutting edge has a V-shape that is convex toward the front side when viewed from above, The opening angle of the cutting edge when viewed from above is 55° or less. The clamping structure for a cutting insert according to any one of claims 1 to 3.

7. The supporter has a vertically inverted symmetrical shape. The clamping structure for a cutting insert according to any one of claims 1 to 3.

8. the recess has a pair of grooves into which the pair of protrusions are inserted, The groove is a bottomed groove. The clamping structure for a cutting insert according to any one of claims 1 to 3.

9. The clamping structure for a cutting insert according to any one of claims 1 to 3; The tool body; the clamping member that fixes the clamping structure of the cutting insert to the insert mounting seat, Indexable cutting tool.

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