Interchangeable tip milling tool and holder

Abstract

To provide an interchangeable-tip milling tool and holder that can increase the rigidity and strength of the tool while maintaining good chip evacuation performance. [Solution] The tool comprises a holder 2 and a plurality of cutting inserts 1. The holder 2 has a plurality of insert mounting seats 22 arranged circumferentially at intervals from each other on the outer circumference of the tip of the holder 2, to which each cutting insert 1 is detachably attached, and a plurality of chip pockets 23 that are recessed from the tip surface and outer circumference of the holder 2 and are formed extending in the tool rotation direction and to the axial rear end of each insert mounting seat 22. Each chip pocket 23 has a rear end protrusion 25 located on the axial rear end side of the wall portion of the chip pocket 23 that faces away from the tool rotation direction. The rear end protrusion 25 has a convex shape that protrudes toward at least one of the axial tip side and the opposite side of the tool rotation direction when viewed from the radially outside of the tool in a side view of the tool.

Description

Technical Field

[0001] The present invention relates to an insert-exchangeable turning tool and a holder.

Background Art

[0002] Conventionally, an insert-exchangeable turning tool (insert-exchangeable milling tool) including a holder that is rotated in a tool rotation direction around a central axis, and a plurality of cutting inserts arranged at intervals in the circumferential direction on the outer peripheral portion of the tip of the holder is known (for example, Patent Document 1). Further, the holder has a plurality of insert mounting seats arranged at intervals in the circumferential direction on the outer peripheral portion of the tip of the holder, to which each cutting insert is detachably attached, and a plurality of chip pockets formed in a concave shape recessed from the tip surface and the outer peripheral surface of the holder, extending in the tool rotation direction and the axially rear end side of each insert mounting seat.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, in machine tools such as machining centers, with the improvement of output and torque, cutting at higher feed rates and rotational speeds has become possible. Accordingly, there is a demand for improving the rigidity and strength of insert-exchangeable turning tools mounted on machine tools so as to be adaptable to high-load cutting.

[0005] To increase the rigidity and strength of the tool, for example, the following methods can be considered. The circumferential dimensions of the part of the holder located between the insert mounting seat where the cutting insert is placed and the chip pocket adjacent to the insert mounting seat in the direction opposite to the tool's rotation—that is, the part that supports the cutting insert from the direction opposite to the tool's rotation (hereinafter sometimes referred to as the back metal)—are made larger. This increases the rigidity of the back metal, so that even during cutting operations at high feed rates and high rotation speeds, deformation of the holder and displacement of the cutting edge position of the cutting insert are suppressed, and machining accuracy can be ensured.

[0006] However, there is a trade-off between the circumferential dimensions of the back metal and the circumferential dimensions of the chip pocket. In other words, simply increasing the circumferential dimensions of the back metal will decrease the circumferential dimensions of the chip pocket, making it difficult to maintain good chip evacuation. This problem of chip evacuation is particularly likely to occur in cutting operations where the area around the tool tip is covered by the machined surface (wall) of the workpiece (for example, groove machining or pocket machining).

[0007] The present invention aims to provide an interchangeable cutting edge milling tool and holder that can increase the rigidity and strength of the tool and maintain good chip evacuation performance. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides the following means.

[0009] [Aspect 1 of the present invention] An interchangeable-tip milling tool comprising a holder that can be rotated in the direction of tool rotation about a central axis, and a plurality of cutting inserts arranged circumferentially at intervals from each other on the outer circumference of the tip of the holder, wherein the holder has a plurality of insert mounting seats arranged circumferentially at intervals from each other on the outer circumference of the tip of the holder, to which each cutting insert is detachably attached, and a plurality of chip pockets that are recessed from the tip surface and outer surface of the holder, and are formed extending from the tool rotation direction and the axial rear end side of each insert mounting seat, wherein each chip pocket has a rear end protrusion located on the axial rear end side of the wall portion of the chip pocket facing the opposite direction of tool rotation, and the rear end protrusion has a convex shape that protrudes toward at least one of the axial tip side and the opposite direction of tool rotation when viewed radially from the outside of the tool.

[0010] In the indexable milling tool of the present invention, the chip pocket has a rear-end protrusion, and the rear-end protrusion is located on the axial rear end side of the cutting insert among the wall portion of the chip pocket that faces the opposite direction to the tool rotation direction (anti-tool rotation direction). The rear-end protrusion has a shape that is convex toward at least one of the axial front end side and the anti-tool rotation direction when viewed from the side of the tool.

[0011] This ensures that the circumferential dimensions of the back metal, which supports the cutting insert from the opposite direction of tool rotation, are large in the holder, specifically in the portion located between the insert mounting seat where the cutting insert is positioned and the chip pocket adjacent to the insert mounting seat in the opposite direction of tool rotation. In particular, sufficient circumferential dimensions (i.e., wall thickness) are ensured in the portion of the back metal located axially towards the rear end of the cutting insert (near the rear end, which forms the root of the back metal). This increases the rigidity of the back metal, suppressing deflection deformation of the back metal even during cutting operations at high feed rates and high rotation speeds. As a result, deformation of the holder and displacement of the cutting edge position of the cutting insert are suppressed, ensuring machining accuracy.

[0012] Furthermore, the portion of the chip pocket located axially towards the front end rather than the rear end protrusion ensures that the circumferential dimensions of the chip pocket are maintained. This ensures good chip evacuation of chips generated by the cutting edge of the cutting insert and directed toward the tool rotation direction. In addition, this chip pocket is formed extending axially towards the rear end of the insert mounting seat. Therefore, chips generated by the cutting edge of the cutting insert and directed toward the axial rear end pass through the region of the chip pocket that extends axially from the insert mounting seat toward the rear end and are discharged to the outside of the chip pocket.

[0013] According to the present invention, chip clogging in the chip pocket is suppressed, and good chip evacuation performance can be maintained. In particular, good chip evacuation performance is maintained even in cutting operations where the area around the tool tip is covered by the machined surface (wall) of the workpiece (for example, groove machining or pocket machining).

[0014] Based on the above, the present invention makes it possible to increase the rigidity and strength of the tool while maintaining good chip evacuation performance.

[0015] [Aspect 2 of the present invention] The rear end protrusion has a curved convex portion that extends in a curved shape when viewed from the side of the tool, as described in Embodiment 1 of the replaceable cutting edge milling tool.

[0016] In this case, the curved convex section prevents problems such as chips getting caught on the convex section at the rear end. This allows for more stable and improved chip evacuation.

[0017] [Aspect 3 of the present invention] Each chip pocket has a tip-side protrusion located at least at the tip of the wall portion of the chip pocket facing the opposite direction of the tool rotation, and the tip-side protrusion has a convex shape that protrudes toward the opposite direction of the tool rotation when viewed from the axial tip side of the replaceable tip milling tool. This is the replaceable tip milling tool according to embodiment 1 or 2.

[0018] In the above configuration, the chip pocket further has a tip-side convex portion, and the tip-side convex portion is disposed at least at the tip of the wall portion facing the counter-tool rotation direction of the chip pocket. The tip-side convex portion has a shape that protrudes in the counter-tool rotation direction when viewed from the tool tip side.

[0019] Thereby, a large circumferential dimension of the back metal is ensured. In particular, at the tip of the back metal that supports the cutting edge of the cutting insert used for cutting, a sufficient circumferential dimension (i.e., wall thickness) is ensured. As a result of enhancing the rigidity of the back metal in this way, even during cutting with high feed or high-speed rotation, deformation of the holder and displacement of the cutting edge position of the cutting insert are suppressed, and machining accuracy can be ensured.

[0020] Also, in the view from the tool tip, for the portion located radially outside the top of the tip-side convex portion (hereinafter sometimes referred to as the outer portion of the tip-side convex portion), it will extend in the tool rotation direction as it goes radially outward. Thereby, a sufficient circumferential dimension between the outer portion of the tip-side convex portion and the cutting edge of the cutting insert is ensured. That is, since a large space (the space adjacent to the cutting edge in the tool rotation direction) for discharging the chips generated by the cutting edge to the outside of the chip pocket is ensured, chip clogging in the chip pocket is suppressed, and chip evacuation performance can be maintained well. In particular, even in cutting such as groove cutting or pocket cutting where the periphery of the tool tip is covered by the machined surface (wall surface) of the workpiece, chip evacuation performance is maintained well.

[0021] 〔Aspect 4 of the present invention〕 The edge-exchangeable turning tool according to Aspect 3, wherein the tip-side convex portion has a convex curve portion that extends in a curved shape in the view from the tool tip.

[0022] In this case, the problem that chips get caught on the tip-side convex portion is suppressed by the curved convex curve portion. Chip evacuation performance is more stably enhanced.

[0023] 〔Aspect 5 of the present invention〕 The cutting-edge replaceable turning tool according to aspect 3 or 4, wherein the top of the tip-side convex portion is located radially inward of the midpoint of the entire length of the tip-side convex portion in a view from the tool tip.

[0024] In this case, a length of a portion of the tip-side convex portion located radially outside the top (outer portion of the tip-side convex portion) is ensured to be large. Thereby, a circumferential dimension between the outer portion of the tip-side convex portion and the cutting edge of the cutting insert is further increased. That is, since a space adjacent to the cutting edge in the tool rotation direction in the chip pocket is ensured to be wider, chip evacuation performance is improved.

[0025] 〔Aspect 6 of the present invention〕 The cutting-edge replaceable turning tool according to any one of aspects 3 to 5, wherein the insert mounting seat has a mounting surface facing the tool rotation direction and contacting the seating surface of the cutting insert, and an angle formed between the mounting surface and the radially outer end portion of the tip-side convex portion in a view from the tool tip is larger than 81°.

[0026] Since the angle is larger than 81°, a circumferential dimension between the radially outer end portion of the tip-side convex portion and the cutting edge of the cutting insert mounted on this insert mounting seat is ensured to be sufficiently large. Thereby, chip evacuation performance is more stably enhanced.

[0027] 〔Aspect 7 of the present invention〕 The cutting-edge replaceable turning tool according to any one of aspects 1 to 6, further comprising a plurality of fixing screws for fixing each of the cutting inserts to the holder, wherein each of the chip pockets has a stealing portion disposed axially at a tip side of the rear-end side convex portion on a wall portion facing a side opposite to the tool rotation direction of the chip pocket, the stealing portion has a concave shape recessed in the tool rotation direction, and at least a part of a screw head of the fixing screw and the stealing portion do not overlap when a rake face of the cutting insert is viewed from the tool rotation direction.

[0028] In this case, a recessed recess is provided in the wall of the chip pocket facing the opposite direction of tool rotation. When attaching or detaching the cutting insert to the insert mounting seat of the holder using a fixing screw, the space adjacent to the recessed recess in the opposite direction of tool rotation (the recessed space formed by the recess) can be used to prevent problems such as work tools such as wrenches interfering with the wall. This makes it easier to engage the work tool with the screw head of the fixing screw and to operate it, thus improving the ease of attaching and detaching the cutting insert.

[0029] [Aspect 8 of the present invention] A holder that can be rotated in the direction of tool rotation around a central axis, comprising: a plurality of insert mounting seats arranged circumferentially at intervals from each other on the outer circumference of the tip of the holder; and a plurality of tip pockets that are recessed from the tip surface and the outer circumference of the holder, and are formed extending in the direction of tool rotation and to the axial rear end of each insert mounting seat, wherein each tip pocket has a rear end protrusion located on the axial rear end side of the wall portion of the tip pocket facing the opposite direction of tool rotation, and the rear end protrusion has a convex shape that protrudes toward at least one of the axial tip side and the opposite direction of tool rotation when the holder is viewed radially from the outside of the tool.

[0030] The holder of the present invention provides the same excellent performance and effects as the replaceable-tip milling tool of the present invention described above. Therefore, it is possible to increase the rigidity and strength of the tool and maintain good chip evacuation performance. [Effects of the Invention]

[0031] According to the above-described aspect of the present invention, an interchangeable cutting edge milling tool and holder are provided that can increase the rigidity and strength of the tool and maintain good chip evacuation performance. [Brief explanation of the drawing]

[0032] [Figure 1] Figure 1 is a perspective view showing the replaceable-tip milling tool of this embodiment. [Figure 2] Figure 2 is a front view of the replaceable-tip milling tool of this embodiment, as seen from the tool tip side. [Figure 3] Figure 3 is a side view of the replaceable-tip milling tool shown in Figure 2, viewed from the direction of arrow III. [Figure 4] Figure 4 is a perspective view showing the holder of this embodiment. [Figure 5] Figure 5 is a front view of a part of the replaceable-tip milling tool of this embodiment, as seen from the tool tip side. [Figure 6] Figure 6 is a side view of the replaceable-tip milling tool shown in Figure 2, viewed from the direction of arrow VI. [Figure 7] Figure 7 is a front view of a part of a first modified example of this embodiment, an interchangeable-tip milling tool, as seen from the tool tip side. [Figure 8] Figure 8 is a front view of a part of a second modified example of this embodiment, a replaceable-tip milling tool, as seen from the tool tip side. [Figure 9] Figure 9 is a side view showing a third modified example of this embodiment of an interchangeable-tip milling tool. [Figure 10] Figure 10 is a perspective view showing a conventional replaceable-tip milling tool. [Figure 11] Figure 11 is a front view of a conventional replaceable-tip milling tool, seen from the tool tip side. [Figure 12] Figure 12 is a side view of the replaceable-tip milling tool shown in Figure 11, viewed from the direction of arrow XII. [Modes for carrying out the invention]

[0033] An example of an interchangeable-tip milling tool (exchangeable-tip milling tool) 10 and holder 2 will be described with reference to Figures 1 to 6. The interchangeable-tip milling tool 10 of this embodiment is, for example, an interchangeable-tip end mill, interchangeable-tip cutter, interchangeable-tip milling cutter, etc., used to perform milling on a workpiece such as metal. In this embodiment, the interchangeable-tip milling tool 10 and holder 2 may be simply referred to as a tool, etc.

[0034] As shown in Figures 1 to 4, the replaceable-tip milling tool 10 comprises a holder 2, a plurality of cutting inserts 1 that are detachably attached to the holder 2, and a plurality of fixing screws 3 that secure each cutting insert 1 to the holder 2. The holder 2 is substantially cylindrical or cylindrical in shape with a central axis (tool central axis) O. The cutting inserts 1 are plate-shaped with an insert central axis C. In this embodiment, the cutting inserts 1 are polygonal plates, specifically rectangular plates.

[0035] [Definition of direction] In this embodiment, the direction in which the central axis O of the holder 2 extends, that is, the direction along the central axis O, is called the axial direction. Of the two ends of the holder 2 in the axial direction, a cutting insert 1 is placed at the first end 2a, and a spindle of a machine tool (not shown) is attached to the second end 2b. Of the axial directions, the direction from the second end 2b of the holder 2 toward the first end 2a is called the axial front end side or simply the front end side, and the direction from the first end 2a toward the second end 2b is called the axial rear end side or simply the rear end side.

[0036] The direction perpendicular to the central axis O is called the radial direction. Within the radial direction, the direction approaching the central axis O is called the radially inward direction, and the direction moving away from the central axis O is called the radially outward direction.

[0037] The direction of rotation around the central axis O is called the circumferential direction. Of the circumferential directions, the direction in which the holder 2 is rotated during cutting is called the tool rotation direction T, and the rotation direction opposite to this is called the opposite side of the tool rotation direction T or the anti-tool rotation direction. In this embodiment, as shown in Figure 2, when viewing the tool from the axial tip side (i.e., a view of the tool tip from the axial tip side), the counterclockwise rotation direction around the central axis O corresponds to the tool rotation direction T, and the clockwise rotation direction corresponds to the opposite tool rotation direction.

[0038] The axial direction mentioned above may be referred to as the tool axis direction, to distinguish it from the insert axis direction described later. Similarly, the radial direction mentioned above may be referred to as the tool radial direction, to distinguish it from the insert radial direction described later. Furthermore, the circumferential direction mentioned above may be referred to as the tool circumferential direction, to distinguish it from the insert circumferential direction described later.

[0039] In Figure 1, the direction in which the insert central axis C of each cutting insert 1 extends is called the insert axis direction. The cutting insert 1 has a pair of plate surfaces 11 and 12 facing the insert axis direction. Of the pair of plate surfaces 11 and 12, one plate surface 11 faces one side of the insert axis direction, and the other plate surface 12 faces the other side of the insert axis direction.

[0040] One plate surface 11 may be referred to as the front surface 11 or the rake face 11. The other plate surface 12 may be referred to as the back surface 12 or the seating surface 12. One side in the insert axis direction may be referred to as the front surface 11 side in the insert axis direction or the rake face 11 side in the insert axis direction. The other side in the insert axis direction may be referred to as the back surface 12 side in the insert axis direction or the seating surface 12 side in the insert axis direction. The insert axis direction may also be referred to as the thickness direction (plate thickness direction) of the cutting insert 1.

[0041] Furthermore, the direction perpendicular to the insert's central axis C is called the insert's radial direction. Within the insert's radial direction, the direction approaching the insert's central axis C is called the inside of the insert's radial direction, and the direction moving away from the insert's central axis C is called the outside of the insert's radial direction. Furthermore, the direction in which the movement revolves around the central axis C of the insert is called the circumferential direction of the insert.

[0042] [Cutting inserts] The cutting insert 1 is made of a hard sintered body, such as cemented carbide. As shown in Figures 1 to 3, multiple cutting inserts 1 are arranged around the outer circumference of the tip of the holder 2, spaced apart from each other in the circumferential direction. In this embodiment, three cutting inserts 1 are provided around the outer circumference of the tip of the holder 2 at equal pitches in the circumferential direction. Note that the number of cutting inserts 1 is not limited to three; there may be two, four or more. Furthermore, multiple cutting inserts 1 may be arranged at unequal pitches in the circumferential direction.

[0043] The cutting insert 1 in this embodiment is rectangular or parallelogram-shaped. When the cutting insert 1 is attached to the holder 2, the longitudinal direction (surface direction) perpendicular to the insert's central axis C of the cutting insert 1 generally corresponds to the axial direction of the tool, and the short direction generally corresponds to the radial direction of the tool.

[0044] Furthermore, the cutting insert 1 has a shape that is 180° rotationally symmetrical with respect to the insert's central axis C. Also, the cutting insert 1 does not have a front-to-back inverted symmetrical shape. The cutting insert 1 in this embodiment is a so-called single-sided type positive insert.

[0045] The cutting insert 1 has a pair of plate surfaces 11 and 12 facing in the direction of the insert axis, an outer peripheral surface 13 facing outward in the radial direction of the insert and extending in the circumferential direction of the insert, a cutting edge 14, and a through hole 15.

[0046] One of the board surfaces 11 (surface 11, scooping surface 11) is rectangular in shape, and in this embodiment, it is rectangular or parallelogram-shaped. The four sides arranged around the outer periphery of one of the board surfaces 11 include a pair of long sides and a pair of short sides extending in a direction intersecting the long sides.

[0047] One of the plate surfaces 11 extends inward from the cutting edge 14 in the radial direction of the insert, and then extends toward the other side in the axial direction of the insert (the back surface 12 side, the seating surface 12 side). That is, when a virtual plane perpendicular to the insert's central axis C is used as the reference plane, the rake angle of one of the plate surfaces (rake face) 11 is a positive angle (conformal angle).

[0048] Although detailed illustrations are omitted, the other plate surface 12 (back surface 12, seating surface 12) is rectangular in shape, and in this embodiment, it is rectangular or parallelogram-shaped. The surface area of ​​the other plate surface 12 is smaller than the surface area of ​​the one plate surface 11. The other plate surface 12 is planar in shape, extending in a direction perpendicular to the insert's central axis C.

[0049] The outer circumferential surface 13 is annular in shape, extending around the central axis C of the insert. When the cutting insert 1 is attached to the holder 2, the outer circumferential surface 13 has a pair of sides facing the axial direction of the tool (a front side facing the axial tip and a rear side facing the axial rear end) and a pair of sides facing the radial direction of the tool (a left side facing radially inward and a right side facing radially outward).

[0050] One end of the outer peripheral surface 13 in the insert axial direction is connected to the outer periphery of one of the plate surfaces 11 via the cutting edge 14. The outer peripheral surface 13 is positioned along the long and short sides of one of the plate surfaces 11 and extends along the cutting edge 14. The outer peripheral surface 13 may also be referred to as the relief surface 13. The other end of the outer peripheral surface 13 in the insert axial direction is connected to the outer periphery of the other plate surface 12.

[0051] The outer peripheral surface 13 extends inward in the radial direction of the insert as it moves from the cutting edge 14 toward the other side in the insert axial direction. This makes it easy to create a relief angle between the machined surface of the workpiece and the relief surface 13 during cutting, and increases the degree of freedom in the mounting position of the cutting insert 1 to the holder 2.

[0052] The cutting edge 14 is positioned on the ridge where the rake face 11 and the relief face 13 are connected. The cutting edge 14 is positioned along both the long and short sides of one of the plate surfaces 11, and in this embodiment, it has a roughly L-shape.

[0053] Multiple cutting edges 14 are provided on the cutting insert 1. In this embodiment, the cutting insert 1 is a single-sided positive insert having a shape that is 180° rotationally symmetric with respect to the insert's central axis C, and two cutting edges 14 are provided at positions that are 180° rotationally symmetric to each other with respect to the insert's central axis C. The two cutting edges 14 have a common configuration. Below, one of the two cutting edges 14 (the cutting edge 14 used for cutting when the cutting insert 1 is mounted on the holder 2) will be described.

[0054] The cutting edge 14 has a main cutting edge 17, a secondary cutting edge 18, a corner edge 19, and an inner edge 20. The main cutting edge 17 is positioned on the longer side of one of the four sides of the plate surface 11. As shown in Figure 3, when the cutting insert 1 is viewed from one side in the direction of the insert axis, the main cutting edge 17 is in the shape of a straight line extending in the direction of the tool axis. Alternatively, the main cutting edge 17 may be in the shape of a convex curve with a large radius of curvature (large R) that bulges slightly outward in the radial direction of the tool. During cutting, the main cutting edge 17 functions as the outer cutting edge of the replaceable tip milling tool 10.

[0055] The secondary cutting edge 18 is positioned on the shorter side of one of the four sides of the plate surface 11. When the cutting insert 1 is viewed from one side in the direction of the insert axis, the secondary cutting edge 18 is in the shape of a straight line extending in the radial direction of the tool. Alternatively, the secondary cutting edge 18 may be in the shape of a convex curve with a large radius of curvature (large R) that bulges slightly toward the axial tip side of the tool. During cutting, the secondary cutting edge 18 functions as the bottom cutting edge of the replaceable tip milling tool 10.

[0056] The corner blade 19 is positioned at the corner where the long and short sides of one of the plate surfaces 11 meet. The corner blade 19 is connected to the main cutting blade 17 and the secondary cutting blade 18. In this embodiment, the corner blade 19 has a curved shape that is convex toward the outer circumference of the tip of the tool.

[0057] One end of the corner blade 19 is connected to the tip of the main cutting edge 17. The other end of the corner blade 19 is connected to the radially outer end of the secondary cutting edge 18. The corner blade 19 extends radially inward from the end connected to the main cutting edge 17 toward the axial tip.

[0058] The inner blade 20 is positioned on the shorter side of one of the four sides of the plate surface 11. On the shorter side, the inner blade 20 is positioned radially inward of the secondary cutting edge 18. The inner blade 20 extends towards the axial rear end as it moves radially inward towards the tool. The inner blade 20 may function as a cutting edge, for example, during ramping. However, the inner blade 20 does not have to function as a cutting edge (it may be a dummy cutting edge).

[0059] As shown in Figures 1 and 3, the through-hole 15 penetrates the cutting insert 1 in the direction of the insert axis. The through-hole 15 extends within the cutting insert 1 in the direction of the insert axis and opens into a pair of plate surfaces 11 and 12. The through-hole 15 has a circular cross-section perpendicular to the insert's central axis C. In this embodiment, one through-hole 15 is provided in the cutting insert 1. The central axis of the through-hole 15 is coaxial with the insert's central axis C.

[0060] [Holder] The holder 2 is made of metal, such as steel. As shown in Figure 4, in this embodiment, the holder 2 is substantially cylindrical in shape and extends axially along the central axis O. The holder 2 is detachably mounted on the spindle of a machine tool (not shown). The holder 2 is rotated by the spindle of the machine tool in the tool rotation direction T around the central axis O. During cutting, the holder 2 is also fed radially by the spindle of the machine tool. In this way, by rotating the holder 2 and providing feed, the cutting edges 14 of the multiple cutting inserts 1 attached to the holder 2 cut into the workpiece, and various milling operations are performed.

[0061] The holder 2 has a plurality of insert mounting seats 22 arranged circumferentially at intervals from each other on the outer circumference of the tip of the holder 2, to which each cutting insert 1 is detachably attached, and a plurality of chip pockets 23 that are recessed from the tip surface and outer circumference of the holder 2 and are formed extending across the tool rotation direction T and the axial rear end of each insert mounting seat 22.

[0062] The insert mounting seat 22 is positioned at the first end 2a (i.e., the tip) of the holder 2 and opens to the tip surface and outer circumferential surface of the holder 2. The insert mounting seat 22 is concave, recessed from the tip surface and outer circumferential surface of the holder 2. The insert mounting seat 22 is formed to cut out the tip outer circumferential portion of the wall portion of the tip pocket 23 that faces the tool rotation direction T.

[0063] As shown in Figures 1 to 3, a portion of the cutting insert 1 (such as the portion other than the cutting edge 14) is placed inside the insert mounting seat 22. The shape of the insert mounting seat 22 corresponds to the shape of the cutting insert 1, and in this embodiment, it is a rectangular hole. Specifically, the shape of the insert mounting seat 22 is a rectangular hole or a parallelogram hole.

[0064] In this embodiment, three insert mounting seats 22 are provided on the outer circumference of the tip of the holder 2 at equal pitches in the circumferential direction. The number of insert mounting seats 22 is the same as the number of cutting inserts 1. Multiple cutting inserts 1 of the same shape are mounted on the multiple insert mounting seats 22. Each cutting insert 1 is detachably attached to each insert mounting seat 22. Note that the number of insert mounting seats 22 is not limited to three; it may be two, four or more. Also, the multiple insert mounting seats 22 may be provided at unequal pitches in the circumferential direction.

[0065] As shown in Figure 4, the insert mounting seat 22 has a mounting surface 22a located at the end of the insert mounting seat 22 opposite to the tool rotation direction and facing the tool rotation direction T, an inner wall surface 22b located at the radially inner end of the insert mounting seat 22 and facing radially outward, a rear end side wall surface 22c located at the axial rear end of the insert mounting seat 22 and facing the axial front side, and a female screw hole 22d.

[0066] As shown in Figure 5, the mounting surface 22a contacts the seating surface 12 of the cutting insert 1. As shown in Figure 4, the mounting surface 22a is planar. The mounting surface 22a supports the cutting insert 1 from the direction opposite to the tool rotation.

[0067] As shown in Figure 2, the inner wall surface 22b contacts the outer circumferential surface 13 of the cutting insert 1. Specifically, the inner wall surface 22b contacts the left side of the outer circumferential surface 13 of the cutting insert 1, which faces radially inward. As shown in Figure 4, the inner wall surface 22b is planar. The inner wall surface 22b supports the cutting insert 1 from the radially inward side.

[0068] As shown in Figure 3, the rear end side wall surface 22c contacts the outer circumferential surface 13 of the cutting insert 1. Specifically, the rear end side wall surface 22c contacts the rear side surface of the outer circumferential surface 13 of the cutting insert 1 that faces the axial rear end. As shown in Figure 4, the rear end side wall surface 22c is planar. The rear end side wall surface 22c supports the cutting insert 1 from the axial rear end side.

[0069] The female screw hole 22d opens into the mounting surface 22a and extends in a direction substantially perpendicular to the direction in which the mounting surface 22a expands. More specifically, of the two ends of the female screw hole 22d, the end in the tool rotation direction T opens into the mounting surface 22a, and the end in the opposite direction of tool rotation opens into the outer circumferential surface of the holder 2. In this embodiment, the female screw hole 22d is a through hole. However, it is not limited to this, and the female screw hole 22d may be a bottomed hole that opens only into the mounting surface 22a and not into the outer circumferential surface of the holder 2. The female screw hole 22d has a female screw portion on its inner circumferential surface.

[0070] The chip pocket 23 opens to the front and outer surfaces of the holder 2. As shown in Figure 6, the chip pocket 23 is groove-shaped and extends from the front surface of the holder 2 toward the axial rear end. Specifically, the chip pocket 23 extends in the direction opposite to the tool rotation as it is toward the axial rear end. The chip pocket 23 is positioned adjacent to the insert mounting seat 22 on the tool rotation direction T and axial rear end side of the insert mounting seat 22.

[0071] The circumferential dimension (maximum value) of the chip pocket 23 is greater than the circumferential dimension of the insert mounting seat 22. Also, the axial dimension of the chip pocket 23 is greater than the axial dimension of the insert mounting seat 22. In Figure 6, the dimension L that the chip pocket 23 extends axially toward the rear end of the insert mounting seat 22 is, for example, 1 / 2 or more of the axial dimension (total axial length) of the cutting insert 1. In other words, the axial dimension (total axial length) of the chip pocket 23 is 1.5 times or more of the axial dimension of the cutting insert 1.

[0072] As shown in Figure 4, in this embodiment, three chip pockets 23 are provided at equal pitches in the circumferential direction on the outer circumference of the holder 2, excluding the rear end. The number of chip pockets 23 is the same as the number of insert mounting seats 22. Note that the number of chip pockets 23 is not limited to three; it may be two, four or more. Furthermore, multiple chip pockets 23 may be provided at unequal pitches in the circumferential direction.

[0073] As shown in Figures 1 to 6, each chip pocket 23 has a tip-side protrusion 24 located at least at the tip of the wall portion of the chip pocket 23 facing the opposite direction of tool rotation T, a rear-end side protrusion 25 located on the rear axial end side of the cutting insert 1 and insert mounting seat 22 of the wall portion of the chip pocket 23 facing the opposite direction of tool rotation T, and a recessed portion 26 located on the wall portion of the chip pocket 23 facing the opposite direction of tool rotation T.

[0074] As shown in Figure 5, in a view of the tool tip of the replaceable-tip milling tool 10 and holder 2 from the axial tip side, the tip-side protrusion 24 has a convex shape that protrudes in the opposite direction to the tool rotation direction T. Also, in this view of the tool tip, the angle θ formed between the mounting surface 22a of the insert mounting seat 22 and the radially outer end of the tip-side protrusion 24 is greater than 81°. In this embodiment, the angle θ is 90° or greater, specifically, for example, about 95°.

[0075] The tip-side protrusion 24 has a apex 24a that is located furthest in the direction opposite to the tool rotation. The apex 24a is the portion of the tip-side protrusion 24 that protrudes furthest in the direction opposite to the tool rotation. In this embodiment, as shown in the tool tip view in Figure 5, the apex 24a of the tip-side protrusion 24 is located radially inward from the midpoint of the entire length of the tip-side protrusion 24.

[0076] Furthermore, the tip-side protrusion 24 has a curved convex portion (tip-side convex curve portion) 24b that extends in a curved shape when viewed from the tool tip. The convex curve portion 24b has a curved shape that is convex in the direction opposite to the tool rotation direction T when viewed from the tool tip. The convex curve portion 24b is located in the intermediate portion of the tip-side protrusion 24, at least between the radially outer end and the radially inner end.

[0077] In this embodiment, the top portion 24a described above is positioned on the convex curve portion 24b and constitutes a part of the convex curve portion 24b. Therefore, the top portion 24a has a curved shape that is convex in the direction opposite to the tool rotation when viewed from the tool tip.

[0078] As shown in Figure 6, in a side view of the replaceable-tip milling tool 10 and holder 2 viewed from the radially outside, the rear end projection 25 has a convex shape that protrudes toward at least one of the axial tip side and the opposite direction to the tool rotation direction T. In this embodiment, in this side view of the tool, the rear end projection 25 has a convex shape that protrudes toward the axial tip side and the opposite direction to the tool rotation. Furthermore, the rear end projection 25 protrudes toward the insert mounting seat 22 and the cutting insert 1 which are located adjacent to the chip pocket 23 in the opposite direction to the tool rotation.

[0079] The rear end convex portion 25 has a curved convex portion (rear end convex curved portion) 25a that extends in a curved shape in the tool side view shown in Figure 6. The convex curved portion 25a has a curved shape that is convex toward at least one of the axial tip side and the anti-tool rotation direction in this tool side view. In this embodiment, the convex curved portion 25a has a curved shape that is convex toward the axial tip side and the anti-tool rotation direction in the tool side view.

[0080] As shown in Figures 1 and 3, the recessed portion 26 is located on the axial rear end side of the tip-side protrusion 24 on the wall portion of the tip pocket 23 facing the opposite direction of the tool rotation T. The recessed portion 26 is also located on the axial front end side of the rear-end side protrusion 25 on the wall portion. The recessed portion 26 has a concave shape that is recessed in the direction of the tool rotation T.

[0081] More specifically, the recessed portion 26 has a concave shape that is recessed in the direction of tool rotation T when viewed from the side of the tool or in a longitudinal section parallel to the central axis O. Although not shown in the figures, in a cross-sectional view perpendicular to the central axis O, the recessed portion 26 has a convex shape that protrudes in the direction opposite to the tool rotation.

[0082] As shown in Figure 3, when viewing the rake face 11 of the cutting insert 1 from the direction of tool rotation T, at least a portion of the screw head 3a of the fixing screw 3 and the recessed portion 26 do not overlap. More specifically, when viewing the rake face 11 from the direction of tool rotation T, the locking portion 3b, which is located on the screw head 3a and into which a working tool such as a wrench is secured, and the recessed portion 26 are positioned without overlapping.

[0083] [Fixing screws] As shown in Figures 1 and 3, the fixing screw 3 is, for example, a clamp screw. The fixing screw 3 has a screw head 3a and a screw shaft (not shown) with a smaller outer diameter than the screw head 3a. The screw head 3a has the aforementioned locking portion 3b recessed from the top surface of the screw head 3a. The screw shaft has a male threaded portion on its outer circumference. The male threaded portion of the fixing screw 3 is designed to be screwed into the female threaded portion of the female screw hole 22d.

[0084] Multiple fixing screws 3 detachably secure each cutting insert 1 to each insert mounting seat 22 of the holder 2. Specifically, the fixing screws 3 are inserted through the through holes 15 of the cutting insert 1 and screwed into the female threaded holes 22d of the insert mounting seat 22. This secures the cutting insert 1 to the insert mounting seat 22.

[0085] [Regarding the mounting position of the cutting insert in the holder, etc.] When the cutting insert 1 is attached to the holder 2, the pair of plate surfaces 11 and 12 (front surface 11 and back surface 12) of the cutting insert 1 face in the circumferential direction. Specifically, one plate surface 11 faces the tool rotation direction T, and the other plate surface 12 faces the opposite direction of tool rotation. In other words, the cutting insert 1 of this embodiment is a so-called horizontal-blade type insert. When the cutting insert 1 is mounted on the insert mounting seat 22, as shown in Figure 6, the insert central axis C of the cutting insert 1 extends toward the axial rear end as it faces the tool rotation direction T.

[0086] As shown in Figure 3, with the cutting insert 1 attached to the insert mounting seat 22, the cutting edge 14 is positioned to protrude radially outward from the outer circumferential surface of the holder 2, and also to protrude axially towards the tip of the holder 2.

[0087] As shown in Figure 6, with the cutting insert 1 mounted on the insert mounting seat 22, the main cutting edge 17 of the cutting edge 14 extends toward the tool rotation direction T as it approaches the axial tip. That is, the helix angle of the main cutting edge 17 is a positive angle (conformal angle).

[0088] Furthermore, as shown in Figure 2, with the cutting insert 1 mounted on the insert mounting seat 22, the secondary cutting edge 18 of the cutting edge 14 extends radially outward in the direction of tool rotation T. That is, the radial rake angle (radial rake) of the secondary cutting edge 18 is a positive angle (contrary angle).

[0089] [Effects of this embodiment] In the replaceable tip milling tool 10 of this embodiment, the chip pocket 23 has a rear end protrusion 25, and the rear end protrusion 25 is located on the axial rear end side of the cutting insert 1 among the wall portion of the chip pocket 23 that faces the opposite side (anti-tool rotation direction) from the tool rotation direction T. In a side view of the tool, the rear end protrusion 25 has a shape that is convex toward at least one of the axial tip side and the anti-tool rotation direction.

[0090] As a result, the circumferential dimensions of the back metal 27, which supports the cutting insert 1 from the opposite direction of tool rotation, are increased in the portion of the holder 2 located between the insert mounting seat 22 on which the cutting insert 1 is positioned and the chip pocket 23 adjacent to the insert mounting seat 22 in the opposite direction of tool rotation. In particular, sufficient circumferential dimensions (i.e., wall thickness) are ensured in the portion of the back metal 27 located axially towards the rear end of the cutting insert 1 (near the rear end which forms the root of the back metal 27). This increases the rigidity of the back metal 27, suppressing deflection deformation of the back metal 27 even during cutting operations at high feed rates and high rotation speeds. As a result, deformation of the holder 2 and displacement of the cutting edge 14 position of the cutting insert 1 are suppressed, and machining accuracy can be ensured.

[0091] Furthermore, the portion of the chip pocket 23 located axially towards the front end than the rear end protrusion 25 ensures that the circumferential dimensions of the chip pocket 23 are maintained. As a result, good chip evacuation of chips generated by the cutting edge 14 of the cutting insert 1 and directed toward the tool rotation direction T is maintained. Moreover, this chip pocket 23 is formed extending from the axial rear end of the insert mounting seat 22. Therefore, chips generated by the cutting edge 14 of the cutting insert 1 and directed toward the axial rear end pass through the region of the chip pocket 23 that extends axially from the insert mounting seat 22 toward the axial rear end (the region with dimension L in Figure 6) and are discharged to the outside of the chip pocket 23.

[0092] According to this embodiment, chip clogging in the chip pocket 23 is suppressed, and good chip evacuation performance can be maintained. In particular, good chip evacuation performance is maintained even in cutting operations where the area around the tool tip is covered by the machined surface (wall) of the workpiece (for example, groove machining or pocket machining).

[0093] Based on the above, this embodiment makes it possible to increase the rigidity and strength of the tool while maintaining good chip evacuation performance.

[0094] In this embodiment, the rear end convex portion 25 has a curved convex portion (rear end convex curved portion) 25a that extends in a curved shape when viewed from the side of the tool. In this case, the curved convex portion 25a prevents problems such as chips getting caught on the rear end convex portion 25. Chip evacuation performance is improved more stably.

[0095] In this embodiment, the tip pocket 23 further has a tip-side protrusion 24, the tip-side protrusion 24 is located at least at the tip of the wall portion of the tip pocket 23 that faces the direction opposite to the tool rotation. As shown in Figure 5, the tip-side protrusion 24 has a shape that is convex in the direction opposite to the tool rotation when viewed from the tool tip side.

[0096] This ensures a large circumferential dimension of the back metal 27. In particular, sufficient circumferential dimension (i.e., wall thickness) is ensured at the tip of the back metal 27 that supports the cutting edge 14 of the cutting insert 1 used for cutting from the opposite direction of tool rotation. As a result of this increased rigidity of the back metal 27, deformation of the holder 2 and displacement of the cutting edge 14 position of the cutting insert 1 are suppressed even during cutting operations at high feed rates and high rotational speeds, thereby ensuring machining accuracy.

[0097] Furthermore, in a view of the tool tip, the portion located radially outward from the top 24a of the tip-side protrusion 24 (hereinafter sometimes referred to as the outer portion of the tip-side protrusion 24) extends radially outward in the direction of tool rotation T. This ensures sufficient circumferential space between the outer portion of the tip-side protrusion 24 and the cutting edge 14 of the cutting insert 1. In other words, a large space is secured for discharging the chips generated by the cutting edge 14 to the outside of the chip pocket 23 (the space adjacent to the tool rotation direction T of the cutting edge 14), thus suppressing chip clogging in the chip pocket 23 and maintaining good chip evacuation performance. In particular, good chip evacuation performance is maintained even in cutting operations where the area around the tool tip is covered by the machined surface (wall) of the workpiece (for example, groove machining or pocket machining).

[0098] In this embodiment, the tip-side protrusion 24 has a curved convex portion (tip-side convex curved portion) 24b that extends in a curved shape when viewed from the tool tip. In this case, the curved convex portion 24b prevents problems such as chips getting caught on the tip-side convex portion 24. Chip evacuation performance is improved more stably.

[0099] In this embodiment, the top 24a of the tip-side protrusion 24 is located radially inward from the midpoint of the entire length of the tip-side protrusion 24 when viewed from the tool tip. In this case, the length of the portion of the tip-side protrusion 24 that is located radially outward from the top portion 24a (the outer portion of the tip-side protrusion 24) is increased. As a result, the circumferential dimension between the outer portion of the tip-side protrusion 24 and the cutting edge 14 of the cutting insert 1 is increased. In other words, a wider space is secured in the chip pocket 23 adjacent to the cutting edge 14 in the tool rotation direction T, thus improving chip evacuation.

[0100] Furthermore, in this embodiment, when viewed from the tool tip, the angle θ formed between the mounting surface 22a of the insert mounting seat 22 and the radially outer end of the tip-side protrusion 24 is greater than 81°.

[0101] By making the angle θ greater than 81°, a sufficiently large circumferential dimension is ensured between the radially outer end of the tip-side protrusion 24 and the cutting edge 14 of the cutting insert 1 mounted on the insert mounting seat 22. This allows for more stable and improved chip evacuation.

[0102] Furthermore, in this embodiment, as shown in Figure 3, a recessed recess 26 is provided on the wall of the chip pocket 23 facing the direction of rotation opposite to the tool. When attaching or detaching the cutting insert 1 to the insert mounting seat 22 of the holder 2 using the fixing screw 3, the space adjacent to the recess 26 in the direction of rotation opposite to the tool (the recessed space formed by the recess 26) can be used to suppress problems such as work tools such as wrenches interfering with the wall. This makes it easier to lock the work tool onto the screw head 3a (locking portion 3b) of the fixing screw 3 and to operate, thus improving the ease of attaching and detaching the cutting insert 1.

[0103] Furthermore, the holder 2 of this embodiment provides the same excellent performance and effects as the replaceable-tip milling tool 10 of this embodiment described above. Therefore, it is possible to increase the rigidity and strength of the tool and maintain good chip evacuation performance.

[0104] Here, Figures 10 to 12 show a conventional indexable tip milling tool 100 and holder 102. As shown in Figures 10 to 12, in the conventional indexable tip milling tool 100 and holder 102, the chip pocket 123 does not have a tip-side protrusion 24 and a rear-end-side protrusion 25. For this reason, in the conventional product, the circumferential dimension of the back metal 127 that supports the cutting insert 1 from the opposite direction of tool rotation is smaller than the circumferential dimension of the back metal 27 in this embodiment (the present invention).

[0105] Strength analysis and evaluation were performed on the conventional tools shown in Figures 10 to 12 and the tools of this embodiment described above, under the following cutting conditions, load, loading method, and evaluation method, assuming high feed and high rotation.

[0106] [Assumed cutting conditions] • Blade diameter: φ25mm • Number of teeth: 3 • Feed rate per tooth: fz = 0.08 mm / t • Axial depth of cut ap = 10 mm [Load Capacity] 1800N [Loading Method] The load is set so that the maximum load occurs near the corner cutting edge 19 of the insert mounting seat 22. [Evaluation Method] - Comparative evaluation of the stress (phon mises) in the mounting seat recess 22e (see Figure 4) located between the mounting surface 22a and the inner wall surface 22b of the insert mounting seat 22. - Comparative evaluation of the seat displacement (magnitude) near the outer edge of the tip of the mounting surface 22a of the insert mounting seat 22.

[0107] As a result, it was confirmed that the stress in the recessed portion 22e of the insert mounting seat 22 was improved (reduced) by about 20% in this embodiment (the present invention) compared to the conventional product. Furthermore, it was confirmed that the sheet displacement (deflection) near the outer edge of the mounting surface 22a of the insert mounting seat 22 was improved by about 22% in this embodiment (the present invention) compared to the conventional product (less prone to displacement and less prone to deflection).

[0108] [Other components included in the present invention] The present invention is not limited to the embodiments described above, and modifications to the configuration, etc., are possible without departing from the spirit of the invention, as will be explained below. In the illustration of modified examples, the same reference numerals are used for components that are the same as those in the embodiments described above, and the main differences will be explained below.

[0109] Figure 7 is a front view of a part of the replaceable tip milling tool 10A of the first modified embodiment described above, viewed from the tool tip side. In this first modified embodiment, as shown in Figure 7, when the replaceable tip milling tool 10A and holder 2 are viewed from the axial tip side, the tip-side convex portion 24 has a curved convex curve portion (tip-side convex curve portion) 24b and a straight portion (tip-side straight portion) 24c that extends in a straight line.

[0110] The convex curved portion 24b is positioned across the tip-side convex portion 24a and the portion located radially inward of the tip 24a. The straight portion 24c is positioned on the tip-side convex portion 24, on the portion located radially outward from the tip 24a. As shown in Figure 7, the convex curved portion 24b and the straight portion 24c are connected so as to be in smooth contact with each other without any steps at their connection point. In this view of the tool tip, the straight portion 24c extends linearly toward the tool rotation direction T as it extends radially outward.

[0111] Furthermore, in the view of the tool tip shown in Figure 7, the angle θ formed between the mounting surface 22a of the insert mounting seat 22 and the radially outer end (straight portion 24c) of the tip-side protrusion 24 is greater than 81°. In this first modified example, the angle θ is 85° or greater, specifically, for example, about 87°. In this first modified example, the same excellent effects and advantages as those of the previously described embodiment can be obtained.

[0112] Figure 8 is a front view of a part of the replaceable tip milling tool 10B of the second modified embodiment described above, viewed from the tool tip side. In this second modified embodiment, as shown in Figure 8, the replaceable tip milling tool 10B and holder 2 are viewed from the axial tip side, and the tip-side protrusion 24 has a pair of straight sections (tip-side straight sections) 24c, 24d.

[0113] The pair of straight sections 24c and 24d include one straight section 24c positioned radially outward from the top 24a and the other straight section 24d positioned radially inward from the top 24a. In the tool tip view shown in Figure 8, one straight section 24c extends linearly in the tool rotation direction T as it extends radially outward. In the same tool tip view, the other straight section 24d extends linearly in the opposite direction of tool rotation as it extends radially outward.

[0114] The top portion 24a is positioned at the connection point between one straight portion 24c and the other straight portion 24d. The top portion 24a has a curved shape that is convex in the direction opposite to the tool rotation when viewed from the tool tip. In the tool tip view shown in Figure 8, the opening angle of the top portion 24a (the angle formed between the pair of straight portions 24c and 24d) is obtuse.

[0115] Furthermore, the angle θ is the same as the angle θ in the first modified example described above. In this second modified example, the same excellent effects and advantages as those of the previously described embodiment and modified example can be obtained.

[0116] Figure 9 is a side view showing a third modified example of this embodiment, an interchangeable-tip milling tool 10C. In this third modified example, as shown in Figure 9, in a side view of the tool, the rear end convex portion 25 has a pair of straight portions (rear end straight portions) 25c and 25d, when the interchangeable-tip milling tool 10C and holder 2 are viewed from the radially outward direction.

[0117] The pair of straight sections 25c and 25d include one straight section 25c positioned on the axial rear end side of the most protruding tip 25b of the rear end convex section 25, and the other straight section 25d positioned on the axial front end side of the tip 25b. In the tool side view shown in Figure 9, one straight section 25c extends linearly in the direction opposite to the tool rotation as it approaches the axial rear end. Similarly, in the tool tip view, the other straight section 25d extends linearly in the direction opposite to the tool rotation as it approaches the axial rear end.

[0118] The amount of axial displacement (i.e., inclination) per unit length along the circumferential direction of one straight section 25c is greater than the amount of axial displacement per unit length along the circumferential direction of the other straight section 25d.

[0119] The tip 25b is positioned at the connection point between one straight section 25c and the other straight section 25d. In a side view of the tool, the tip 25b is bent in a convex shape towards the axial tip and in the direction opposite to the tool rotation. In the side view of the tool shown in Figure 9, the opening angle of the tip 25b (the angle formed between the pair of straight sections 25c and 25d) is obtuse. In this third modified example, the same excellent effects and advantages as those of the previously described embodiment and modified example can be obtained.

[0120] Furthermore, while the embodiments and modifications described above show the cutting insert 1 as being rectangular or parallelogram-shaped, it is not limited to these. The cutting insert may be, for example, square or rhombic. In addition, the cutting insert may be polygonal or circular, in addition to being rectangular.

[0121] Furthermore, when viewing the cutting insert 1 from one side in the insert axis direction, the corner cutting edge 19 may be a straight line that intersects the main cutting edge 17 and the secondary cutting edge 18 at obtuse angles. In other words, the corner cutting edge 19 is not limited to the rounded corner shape described in the above embodiment, but may also be a chamfered corner shape.

[0122] Furthermore, the number of through holes 15 provided in the cutting insert 1 is not limited to one. Although not specifically shown, there may be two or more through holes 15 arranged in the cutting insert 1 in the direction of the tool axis. In this case, when viewing the rake face 11 of the cutting insert 1 from the tool rotation direction T, the recessed portion 26 is formed so as not to overlap with at least a part (each locking portion 3b) of each screw head 3a of the multiple fixing screws 3 that are inserted through the multiple through holes 15.

[0123] Furthermore, in the embodiments and modifications described above, a so-called horizontal-blade type insert was given as an example for the cutting insert 1, but it is not limited to this. Although not specifically shown, the cutting insert may also be a so-called vertical-blade type. Specifically, the horizontal-blade type cutting insert 1 is detachably fixed to the insert mounting seat 22 by a fixing screw 3 from the tool rotation direction T, whereas the vertical-blade type cutting insert is detachably fixed to the insert mounting seat by a fixing screw from the radially outer side.

[0124] Furthermore, when using a vertical-blade type cutting insert, a recessed portion is not required on the wall portion of the chip pocket facing the opposite direction of tool rotation. If a recessed portion is not provided, the tip-side protrusion of the chip pocket may be positioned across the tip portion and the intermediate portion located between the tip and the rear end of the wall portion of the chip pocket facing the opposite direction of tool rotation.

[0125] Although not specifically shown in the figures, the holder 2 may also have coolant holes extending inside the holder 2. The coolant holes open into each chip pocket 23, etc., toward the vicinity of each cutting edge 14 of the multiple cutting inserts 1.

[0126] Furthermore, in the embodiments and modifications described above, the tool rotation direction T, in which the tool is rotated, is set to a counterclockwise direction when viewed from the axial tip side, as shown in Figure 2, but this is not limited to this. The tool rotation direction T may also be clockwise when viewed from the axial tip side of the tool. In other words, the present invention is also applicable to replaceable-tip milling tools and holders that differ in operation from the embodiments and modifications described above.

[0127] The present invention may be combined in any way that does not depart from the spirit of the invention, as described in the above embodiments and modifications, and the configurations may be added, omitted, substituted, or otherwise modified. Furthermore, the present invention is not limited by the above embodiments, but is limited only by the claims. [Industrial applicability]

[0128] The interchangeable-tip milling tool and holder of the present invention can increase the rigidity and strength of the tool while maintaining good chip evacuation. Therefore, it has industrial applicability. [Explanation of Symbols]

[0129] 1…Cutting insert 2… Holder 3… Fixing screws 3a... Screw head 10, 10A, 10B, 10C… Interchangeable tip milling tools 11... One side of the board (scooping surface) 12... The other board surface (seat surface) 22…Insert mounting seat 22a…Mounting surface 23…Chip pocket 24…Tip side convex part 24a...Top 24b…Convex curved part (convex curved part on the tip side) 25...Rear end side convex part 25a...Convex curved part (rear end side convex curved part) 26... The Thief Club O…Central axis T…Tool rotation direction θ…Angle

Claims

1. A holder that can be rotated in the direction of tool rotation around a central axis, A replaceable cutting edge milling tool comprising a plurality of cutting inserts arranged circumferentially at intervals from each other on the outer circumference of the tip of the holder, The aforementioned holder is, The holder has a plurality of insert mounting seats arranged circumferentially at intervals from each other on the outer circumference of its tip, to which each cutting insert is detachably attached, The holder has a concave shape extending from the tip surface and outer peripheral surface, and has a plurality of chip pockets formed across the tool rotation direction and the axial rear end side of each insert mounting seat, Each of the chip pockets has a rear end protrusion located on the rear end side of the cutting insert in the axial direction of the wall portion of the chip pocket that faces the opposite direction of the tool rotation, The aforementioned rear end protrusion has a convex shape that protrudes toward at least one of the axial tip side and the opposite direction to the tool rotation direction when viewed from the radially outer side of the replaceable cutting edge milling tool. Interchangeable tip milling tool.

2. The rear end protrusion has a curved convex portion that extends in a curved shape when viewed from the side of the tool. The replaceable tip milling tool according to claim 1.

3. Each of the tip pockets has a tip-side protrusion located at least at the tip of the wall portion of the tip pocket that faces the opposite direction to the tool rotation direction, The aforementioned tip-side protrusion has a convex shape that protrudes in the opposite direction to the tool rotation direction when viewed from the axial tip side of the replaceable-tip milling tool. The replaceable tip milling tool according to claim 1 or 2.

4. The aforementioned tip-side protrusion has a curved convex portion that extends in a curved shape when viewed from the tip of the tool. The replaceable tip milling tool according to claim 3.

5. The top of the tip-side protrusion is located radially inward from the midpoint of the entire length of the tip-side protrusion when viewed from the tool tip. The replaceable tip milling tool according to claim 3.

6. The insert mounting seat has a mounting surface that faces the direction of tool rotation and contacts the seating surface of the cutting insert. In the view of the tool tip, the angle formed between the mounting surface and the radially outer end of the tip-side protrusion is greater than 81°. The replaceable tip milling tool according to claim 3.

7. Each cutting insert is further provided with a plurality of fixing screws for securing it to the holder. Each of the tip pockets has a recessed portion located on the axial tip side of the rear end protrusion in the wall portion of the tip pocket facing the opposite direction of tool rotation, The aforementioned recessed portion has a concave shape that is recessed in the direction of the tool's rotation. When the rake face of the cutting insert is viewed from the direction of tool rotation, at least a portion of the screw head of the fixing screw does not overlap with the recessed portion. The replaceable tip milling tool according to claim 1 or 2.

8. A holder that can be rotated in the direction of tool rotation around a central axis, Multiple insert mounting seats are arranged circumferentially at intervals from each other on the outer circumference of the tip of the holder, The holder has a concave shape extending from the tip surface and outer peripheral surface, and has a plurality of chip pockets formed across the tool rotation direction and the axial rear end side of each insert mounting seat, Each of the chip pockets has a rear end protrusion located on the rear end side of the insert mounting seat, which is part of the wall of the chip pocket facing away from the direction of tool rotation. The aforementioned rear end projection has a convex shape that protrudes toward at least one of the axial tip side and the opposite side to the direction of tool rotation when the holder is viewed from the radially outer side of the tool. Holder.

Images