JP7010051B2 - Cutting inserts and screwed structures for cutting inserts - Google Patents

Description

Patent Law Article 30 Paragraph 2 Applicable Website http: // carbide. mmc. co. jp / newproduct, http: // carbide. mmc. co. jp / newproduct / 201711_vpx, November 10, 2017 Website http: // carbide. mmc. co. jp / products / rotating_tools / face_mills, http: // carbide. mmc. co. jp / products / rotating_tools / face_mills / vpx, November 10, 2017 Website http: // www. mitsubishikarbide. com / application / files / 7315/1185/6217 / vpx_b250j. pdf, November 10, 2017 Website https: // www. youtube. com / user / mmtcjp, October 05, 2017 Website https: // youtu. be / WW910g4CP0w, https: // youtu. be / UCJ6UzdU_Io, October 06, 2017 Website https: // youtu. be / HmWV3LZwz5Y, October 05, 2017 Website https: // youtu. be / NZgT6tNSuvA, October 30, 2017 Website https: // youtu. be / 60GajJyFdHQ, November 21, 2017 Website https: // youtu. be / Go-VofIqduc, October 10, 2017 Website https: // www. youtube. com / watch? v = tvPU5k-bkvo, November 06, 2017 Website http: // www. mitsubishikarbide. com / en / newproduct, November 22, 2017 Website http: // www. mitsubishikarbide. com / en / products / rotating_tools / face_mills, November 22, 2017 Website http: // www. mitsubishikarbide. com / en / newproduct / 201711_vpx, November 22, 2017

Patent Law Article 30, Paragraph 2 Applicable Website http: // www. mitsubishikarbide. com / en / products / rotating_tools / face_mills / vpx, November 22, 2017 Website http: // www. mitsubishikarbide. com / application / files / 2515/1185/6178 / vpx_b250g. pdf, November 22, 2017 Mitsubishi Materials Corporation's TOOLS NEWS, B250J, Multi-functional cutter VPX series for high-efficiency machining (new release), November 10, 2017 MECT official guidebook, October 2017 18th Kaiho, No. 146, January 01, 2018 Manufacturing Review, January issue, January 12, 2018 User Communication, February issue, February 05, 2018 Mechanical Technology, February issue, February 01, 2018 Mold Newspaper, No. 0210, February 10, 2018 Mold Newspaper, No. 0110, January 10, 2018 Mold Newspaper, No. 1016, October 16, 2017 Fri Type Newspaper No. 1110, November 10, 2017 Mold Newspaper, No. 1210, December 10, 2017 Ironworks Association News, New Year Issue, January 01, 2018 Production Goods Marketing, December Issue, December 01, 2017 Equipment Materials, December issue, December 25, 2017 Chubu Kiko Shimbun, 0105, January 05, 2018 Chubu Kiko Shimbun, No. 1010, October 10, 2017 Chubu Keizai Shimbun, No. 1130, November 30, 2017 Nikkan Kogyo Shimbun, No. 1226, December 26, 2017 Nikkan Kogyo Shimbun, No. 0122, January 22, 2018 Nikkan Kogyo Shimbun, No. 1017, 2017 October 17, 2017 Nikkei Sangyo Shimbun, No. 1018, October 18, 2017 Nihon Kikai Shimbun, No. 0205, February 05, 2018 Nihon Sanki Shimbun, No. 1015, October 15, 2017 Japan Sanki Shimbun, No. 1105, November 05, 2017 Nihon Sanki Shimbun, No. 0105, January 05, 2018, Nihon Logistics Shimbun, No. 1010, October 10, 2017, Nagoya Kiko Shimbun, No. 0121, January 21, 2018 Nagoya Kiko Shimbun, No. 1008, October 08, 2017 ORDER BOOK of Tezuka Co., Ltd., January 05, 2018

Application of Article 30, Paragraph 2 of the Patent Act Information on the 2017 DIAEDGE WINTER Campaign of Mitsubishi Materials Co., Ltd., November 08, 2017 DIAEDGE of Mitsubishi Materials Co., Ltd., September 22, 2017 TOOLS NEWS of Mitsubishi Materials Co., Ltd. , B250J, Distribution of PDF data of multifunctional cutter VPX series (new release) for high-efficiency machining, November 10, 2017 Distribution of PDF data of DIAEDGE 2018 calendar of Mitsubishi Materials Corporation, November 14, 2017 Mechatrotech Japan 2017, October 18, 2017 Mitsubishi Materials Toyoki Festival 2017, November 08, 2017 Inventions sold to Shimizu Sangyo Co., Ltd., November 01, 2017 Inventions to Umemura Main Store Co., Ltd. , November 01, 2017, sold inventions to Zeno Shoji Co., Ltd., November 22, 2017, sold inventions to Sugimoto Shoji Co., Ltd., December 14, 2017, invented to Yamashita Machinery Co., Ltd. Sold products, sold inventions to Yuasa Shoji Co., Ltd. on January 09, 2018, sold inventions to Tosa Kiko Co., Ltd. on November 08, 2017, and invented to Tezuka Co., Ltd. on November 07, 2017. Sold products, sold inventions to Horiya Co., Ltd. on November 09, 2017, sold inventions to Izawa Metals Co., Ltd. on November 15, 2017, and sold inventions to Yamazen Tokyo Headquarters on November 13, 2017. Invented product sold, November 07, 2017 Invented product sold to MMC HARTM ETALL GmbH, January 15, 2018

The present invention relates to a cutting insert and a threaded structure of the cutting insert.

Conventionally, the cutting tool of Patent Document 1 below is known. The cutting tool comprises a cutting insert with a clamping hole and a clamping countersunk screw threaded through the clamping hole. The holes for the clamp are the tapered seat that receives the blunt portion of the head of the bleaching screw for clamping, the hole portion through which the shaft portion of the countersunk screw for clamping is passed, and the convex radius formed at the angle between the tapered seat and the hole portion. , Have. The flat head screw for clamping is formed at the corner between the freezing portion of the head and the shaft portion, and has a concave radius having a radius larger than a convex radius. Then, by screwing in the clamp countersunk screw, the surface of the concave radius in the clamp countersunk screw is pressed against the surface of the convex radius in the clamp hole, and the side surface of the cutting insert is pressed against the restraint wall of the holder to fix it.

Japanese Unexamined Patent Publication No. 2005-205527

However, in Patent Document 1, a special structure must be used for the clamp screw. Further, in this type of cutting insert, there is room for improvement in that the wear of the screw member is suppressed so that the fixed state of the cutting insert can be maintained in a good state.

In view of the above circumstances, the present invention provides a cutting insert that can fix a cutting insert without using a special structure for the screw member, suppresses wear of the screw member, and can maintain a good fixed state of the cutting insert, and a screw of the cutting insert. One of the purposes is to provide a stop structure.

One aspect of the cutting insert of the present invention comprises an insert body and a through hole penetrating the insert body, wherein the through hole is located at the end of the through hole in the central axial direction and is the through hole. The taper has a large diameter portion having the largest inner diameter, and a tapered portion connected to the large diameter portion from the inside of the insert in the central axial direction and the inner diameter decreases toward the inside of the insert in the central axial direction. The portion is connected to the large diameter portion, and is connected to the first curved surface portion having a convex curved shape in the cross section including the central axis and the first curved surface portion from the inside of the insert in the central axis direction to connect the central axis. The shape of the including cross section is a convex curve shape, and the cross section includes the second curved surface portion having a radius of curvature larger than the radius of curvature of the first curved surface portion, and the cross section including the central axis has the said first. The one curved surface portion and the second curved surface portion have a common tangent line at a connection point with each other .
Further, one aspect of the cutting insert of the present invention includes an insert main body and a through hole penetrating the insert main body, and the through hole is located at an end portion of the through hole in the central axial direction. It has a large-diameter portion having the largest inner diameter in the through hole, and a tapered portion that is connected to the large-diameter portion from the inside of the insert in the central axial direction and whose inner diameter decreases toward the inside of the insert in the central axial direction. The tapered portion is connected to the large diameter portion, and is connected to the first curved surface portion having a convex curved shape in the cross section including the central axis and the first curved surface portion from the inside of the insert in the central axis direction, and the center thereof. The shape of the cross section including the shaft is a convex curve shape, and the cross section has a second curved surface portion having a radius of curvature larger than the radius of curvature of the first curved surface portion, and the large diameter portion is the insert. It has an outer large diameter portion connected to the outer surface of the main body and an inner large diameter portion connecting the outer large diameter portion and the first curved surface portion, and the inner large diameter portion has a cross-sectional shape including the central axis. Has a third curved surface portion having a concave curved shape.
Further, one aspect of the present invention is a cutting insert provided with an insert body, a through hole penetrating the insert body, an insert mounting seat to which the cutting insert is detachably attached, and an insert inserted into the through hole. , A threaded structure of a cutting insert comprising a screw member screwed into the insert mounting seat, wherein the through hole is located at an end portion of the through hole in the central axial direction and has the largest inner diameter of the through hole. It has a large diameter portion and a tapered portion that is connected to the large diameter portion from the inside of the insert in the central axis direction and whose inner diameter becomes smaller toward the inside of the insert in the central axis direction. A first curved surface portion connected to a large diameter portion and having a convex curved cross section including the central axis, and a cross section shape including the central axis connected to the first curved surface portion from the inside of the insert in the central axis direction. Has a convex curved shape, and has a second curved surface portion having a radius of curvature larger than the radius of curvature of the first curved surface portion in this cross section, and the screw member extends in the central axis direction and is a male screw. It has a screw shaft portion having a portion and a screw head portion having a diameter larger than that of the screw shaft portion and connected to the screw shaft portion from the outside of the insert in the central axis direction, and the screw head portion is the screw. The large diameter portion of the head having the largest outer diameter in the head is connected to the large diameter portion of the head from the inside of the insert in the central axial direction, and the large diameter portion of the head is connected to the inside of the insert in the central axial direction. It has a head tapered portion having a smaller outer diameter and a head ridge line portion located at an intersection ridge line portion between the head large diameter portion and the head tapered portion, and the head tapered portion has at least the head taper portion. The head ridge line portion is arranged with a gap between the first curved surface portion and the first curved surface portion in contact with the connection point between the first curved surface portion and the second curved surface portion.

According to the present invention, the tapered portion of the through hole has a convex curved first curved surface portion and a convex curved first curved surface portion in the cross-sectional view (longitudinal cross section) including the central axis of the through hole. It has a second curved surface portion having a radius of curvature larger than that of the second curved surface portion. That is, in this cross-sectional view, the connection point between the first curved surface portion and the second curved surface portion is an inflection point at which the radius of curvature of the tapered portion changes.

For example, the screw member inserted into the through hole has a screw shaft portion and a screw head having a diameter larger than that of the screw shaft portion. The screw shaft portion is screwed into the insert mounting seat where the cutting insert is arranged. The screw head has a large diameter portion of the head having the largest outer diameter in the screw head, a tapered head portion whose diameter is reduced from the large diameter portion of the head toward the screw shaft portion in the direction of the central axis, and a head. It has a head ridge line portion located at an intersection ridge line portion between the large diameter portion and the head taper portion. In a cross-sectional view including the central axis of the screw member, the tapered portion of the head is a linear shape extending at an angle with respect to the central axis. That is, this screw member has a general shape such as a commercially available product and does not have a special structure.

According to the present invention, the following effects can be obtained by contacting the tapered portion of the head of the screw member with the tapered portion of the through hole.
In the vertical cross-sectional view of the through hole, the tapered portion has a convex curve as a whole. That is, the tapered portion has a convex curved shape as a whole while including two convex curved first curved surface portions and second curved surface portions having different radii of curvature. Therefore, it is possible to prevent the tapered portion and the tapered portion of the head from being in surface contact (so-called solid contact) as a whole. Therefore, the contact position between the tapered portion and the tapered portion of the head in the central axis direction is stable, and the cutting insert is stably fixed to the insert mounting seat by the screw member.

Then, if the head tapered portion is brought into contact with at least the connection point between the first curved surface portion and the second curved surface portion of the tapered portion, in the region located outside the insert in the central axis direction from this connection point, The contact between the ridgeline portion of the head and the first curved surface portion can be suppressed.
Specifically, since the radius of curvature of the first curved surface portion is smaller than the radius of curvature of the second curved surface portion, the first curved surface portion is easily separated from the screw head on the outside of the insert in the central axis direction from the connection point. There is. Since the ridgeline of the head of the screw head is convex and angular, when it comes into contact with the inner peripheral surface of the through hole, chamfer-like wear progresses at an early stage and the fixed state of the cutting insert becomes unstable. Become. On the other hand, according to the present invention, since the ridgeline portion of the head can be easily separated from the inner peripheral surface of the through hole, the progress of wear of the screw head is suppressed, and the fixed state of the cutting insert is maintained satisfactorily.

Further, in the region located inside the insert in the central axis direction from the connection point, a large contact area between the head taper portion and the second curved surface portion can be secured.
Specifically, since the radius of curvature of the second curved surface portion is larger than the radius of curvature of the first curved surface portion, the second curved surface portion tends to come into contact with the screw head inside the insert in the central axis direction from the connection point. As a result, a large contact area between the inner peripheral surface of the through hole and the screw head can be secured, and the fixed state of the cutting insert by the screw member is stabilized. In addition, the progress of wear of the screw head is suppressed, and the fixed state of the cutting insert is maintained well.

From the above, according to the present invention, the cutting insert can be fixed without using a special structure for the screw member, wear of the screw member can be suppressed, and the fixed state of the cutting insert can be maintained satisfactorily.

The cutting insert has a common tangent line at a connection point between the first curved surface portion and the second curved surface portion in a cross section including the central axis .

In this case, in the vertical cross-sectional view of the through hole, the first curved surface portion and the second curved surface portion have a common tangent line at the connection point of each other (that is, they are in contact with each other), so that the connection point is formed in a convex shape, for example. Compared with the above, the progress of partial wear of the screw member is suppressed.
In the cutting insert, the large-diameter portion has an outer large-diameter portion connected to the outer surface of the insert body and an inner large-diameter portion connecting the outer large-diameter portion and the first curved surface portion, and the inner diameter portion. The large diameter portion has a third curved surface portion having a concave curved cross section including the central axis.
In this case, the large-diameter portion and the tapered portion of the through hole are smoothly connected by the third curved surface portion of the large-diameter portion. Therefore, it is possible to secure the strength near the corner angle (recess) of the connection portion between the large diameter portion and the tapered portion, which tends to be low inside the through hole, and the rigidity of the cutting insert is increased. Further, according to the above configuration, it is easy to form the shape of the through hole at the time of manufacturing.

In the cutting insert, in the cross section including the central axis, the connection point between the first curved surface portion and the second curved surface portion is outside the insert in the central axial direction from the central position in the tapered portion in the central axial direction. It is preferable to be arranged in.

In this case, the connection point can be arranged at a position close to the large diameter portion of the tapered portion. Therefore, the portion of the head taper portion that comes into contact with the connection point also has a large outer diameter at the head taper portion, so that the fixed state of the cutting insert by the screw member is more stable. That is, a large contact area (contact circumference) between the inner peripheral surface of the through hole and the screw member around the central axis of the through hole is secured, and the diameter of the contact position is also large to suppress wobbling of the cutting insert. It's easy to do.

In the cutting insert, the insert body may be plate-shaped, and the through hole may be opened to a pair of plate surfaces among the outer surfaces of the insert body.

When the cutting insert is plate-shaped, the cutting insert may easily wobble during cutting, but according to the present invention, the cutting insert is stably fixed by the screw member, and the fixed state of the cutting insert is good. Be maintained.

In the cutting insert, a cutting edge having a peripheral surface connecting a pair of the plate surfaces of the outer surface of the insert body and a portion located at an intersection ridge between the plate surfaces and the cutting edge adjacent to the cutting edge. , A rake surface arranged on the peripheral surface may be provided.

In this case, the cutting insert is a so-called vertical blade type. Generally, in a vertical blade type cutting insert, the threaded member receives a cutting load from the direction perpendicular to the central axis of the threaded member (in the radial direction of the screw) during cutting, so that the fixed state of the cutting insert becomes unstable. However, according to the present invention, the cutting insert is stably fixed by the screw member, and the fixed state of the cutting insert is maintained well.

In the cutting insert, it is preferable that the insert body has a front-back inverted symmetrical shape.

In this case, since the cutting insert has an inverted symmetrical shape, the same effect as described above can be obtained even if the cutting insert is turned upside down and used. The number of cutting edges of the cutting insert is doubled, extending the tool life.

According to one aspect of the present invention, a cutting insert and a cutting insert that can fix a cutting insert without using a special structure for the screw member, suppress wear of the screw member, and can maintain a good fixed state of the cutting insert. A screwed structure is provided.

It is a perspective view of the cutting edge exchange type cutting tool which concerns on one Embodiment of this invention. It is a side view of the cutting tool of a cutting edge exchange type. It is a front view of the cutting tool of a cutting edge exchange type. It is a perspective view of a tool body. It is a side view of a tool body. It is a front view of a tool body. It is a perspective view of the cutting insert which concerns on one Embodiment of this invention. It is the figure which looked at the cutting insert from the 2nd axis direction (the figure which looked at the 2nd surface from the front). It is the figure which looked at the cutting insert from the 1st axis direction (the figure which looked at the 1st surface from the front). It is the figure which looked at the cutting insert from the 3rd axis direction (the figure which looked at the 3rd surface from the front). FIG. 8 is a cross-sectional view taken along the line XI-XI of FIG. It is sectional drawing of XII-XII of FIG. It is sectional drawing which shows the screwing structure of a cutting insert. It is a figure which shows the main part of FIG. 13 in an enlarged manner.

Hereinafter, the screw-fastening structure 8 of the cutting tool 1, the cutting insert 3, and the cutting insert 3 according to the embodiment of the present invention will be described with reference to the drawings.

[Cutting tool with replaceable cutting edge]
The cutting tool 1 with a replaceable cutting edge of the present embodiment is a milling cutter with a replaceable cutting edge having a so-called vertical blade type cutting insert 3. The cutting tool 1 with a replaceable cutting edge performs cutting work such as front cutting and shoulder cutting on a work material such as metal.

As shown in FIGS. 1 to 3, the cutting tool 1 having a replaceable cutting edge includes a tool body 2, a cutting insert 3, and a screw member 20. The tool body 2 is rotated around the tool axis O. The tool axis O is the central axis of the tool body 2. The cutting insert 3 is attached to the tool body 2. The screw member 20 fixes the cutting insert 3 to the tool body 2.

The tool body 2 is detachably attached to a spindle or the like of a machine tool (not shown). Of both ends of the tool body 2 in the tool axis O direction, the first end (one end) is held by the spindle of the machine tool or the like. The cutting insert 3 is arranged at the second end (the other end) different from the first end of both ends of the tool body 2 in the tool axis O direction.

[Definition of direction (orientation) used in this embodiment (Explanation 1)]
In the present embodiment, the direction parallel to the tool axis O of the tool body 2 (direction along the tool axis O) is referred to as the tool axis O direction. Of the tool axis O directions, the direction from the first end of the tool body 2 toward the second end (lower side in FIG. 2) is called the tool tip side, and the second end to the second end. The direction toward the end of 1 (upper side in FIG. 2) is called the tool rear end side.
The direction orthogonal to the tool axis O is called the tool radial direction. Of the tool radial directions, the direction closer to the tool axis O is called the inner side in the tool radial direction, and the direction away from the tool axis O is called the outer side in the tool radial direction.
The direction that orbits around the tool axis O is called the tool circumferential direction. Of the tool circumferential directions, the direction in which the tool body 2 is rotated during cutting is called the tool rotation direction T, and the rotation direction opposite to this is called the direction opposite to the tool rotation direction T (anti-tool rotation direction). ..
The definition of the direction related to the cutting insert 3 and the screwing structure 8 of the cutting insert 3 will be described later separately.

[Tool body]
The tool body 2 is made of a metal such as a steel material. The tool body 2 is columnar or cylindrical. As shown in FIGS. 1 to 6, in the example of the present embodiment, the tool body 2 is cylindrical or cylindrical. The tool body 2 may have a disk shape. The tool body 2 has an insert mounting seat 4, a tip pocket 6, and a coolant hole 7.

[Insert mounting seat (Explanation 1)]
The insert mounting seat 4 is arranged on the outer peripheral portion of the tip of the tool body 2. The insert mounting seat 4 is recessed from the outer peripheral surface of the tool body 2 toward the inside in the tool radial direction. The insert mounting seat 4 is recessed from the front end surface of the tool body 2 toward the rear end side of the tool. The insert mounting seat 4 has a polygonal hole shape. In the example of this embodiment, the insert mounting seat 4 has a quadrangular hole shape. A plurality of insert mounting seats 4 are provided on the tool body 2. The plurality of insert mounting seats 4 are arranged so as to be spaced apart from each other in the tool circumferential direction.

The cutting insert 3 is detachably attached to the insert mounting seat 4. The cutting insert 3 mounted on the insert mounting seat 4 projects at least a portion of the cutting edge 5 (main cutting edge portion 14 described later) outward in the tool radial direction from the outer peripheral surface of the tool body 2. The cutting insert 3 mounted on the insert mounting seat 4 projects at least a portion of the cutting edge 5 (secondary cutting edge portion 15 described later) from the tip surface of the tool body 2 toward the tip of the tool.
The configuration of the insert mounting seat 4 other than the above will be described separately later.

[Chip pocket]
The tip pocket 6 is arranged on the outer peripheral portion of the tip of the tool body 2. The tip pocket 6 is recessed from the outer peripheral surface of the tool body 2 toward the inside in the tool radial direction. The depth at which the tip pocket 6 is recessed from the outer peripheral surface of the tool body 2 toward the inside in the tool radial direction is larger than the depth at which the insert mounting seat 4 is recessed from the outer peripheral surface of the tool body 2 toward the inside in the tool radial direction. big. The tip pocket 6 is recessed from the tip surface of the tool body 2 toward the rear end side of the tool. The depth at which the tip pocket 6 is recessed from the front end surface of the tool body 2 toward the tool rear end side is larger than the depth at which the insert mounting seat 4 is recessed from the tip surface of the tool body 2 toward the tool rear end side.

A plurality of tip pockets 6 are provided in the tool body 2. The plurality of tip pockets 6 are arranged so as to be spaced apart from each other in the tool circumferential direction. The tip pocket 6 is arranged adjacent to the insert mounting seat 4 in the tool rotation direction T. The end of the insert mounting seat 4 in the tool rotation direction T is connected to the end of the tip pocket 6 on the tool tip side. The inside of the insert mounting seat 4 and the inside of the tip pocket 6 communicate with each other.

[Coolant hole]
The coolant hole 7 extends inside the tool body 2. In the example of this embodiment, the coolant hole 7 extends in the tool body 2 in the tool axis O direction. The coolant hole 7 penetrates the tool body 2. The end of the coolant hole 7 on the rear end side of the tool is connected to the spindle of the machine tool or the like. The end of the coolant hole 7 on the tool tip side opens into the tip pocket 6. The coolant hole 7 opens toward the cutting edge 5 of the cutting insert 3 mounted on the insert mounting seat 4. Coolant (cutting fluid, air, etc.) is supplied to the coolant hole 7 through the spindle of the machine tool or the like.

[Cutting insert]
The cutting insert 3 is made of a cemented carbide containing, for example, tungsten carbide and cobalt as components. As shown in FIGS. 7 to 10, the cutting insert 3 includes a plate-shaped insert main body 10, a pair of first surfaces 11 of the outer surfaces of the insert main body 10 facing in the plate thickness direction, a through hole 16, and a second. A surface 12, a third surface 13, and a cutting edge 5 are provided. The through hole 16 penetrates the insert body 10 and opens to the pair of first surfaces 11. The pair of first surfaces 11 is a pair of plate surfaces facing the thickness direction of the insert body 10.

[Insert body (Explanation 1)]
The insert body 10 has a pair of first surfaces 11 and peripheral surfaces on the outer surface of the insert body 10. The peripheral surfaces of the insert body 10 connect the pair of first surfaces 11 to each other. The peripheral surfaces connect the outer peripheral edges of the pair of first surfaces 11 to each other. The second surface 12 and the third surface 13 are arranged on the peripheral surface. The second surface 12 and the third surface 13 are aligned in the circumferential direction on the peripheral surface of the insert main body 10.

The insert body 10 has a polygonal plate shape. In the example of this embodiment, the insert main body 10 has a quadrangular plate shape, and the pair of first surfaces 11 has a quadrangular surface shape. Specifically, the insert body 10 has a rectangular plate shape. Further, the insert body 10 has a front-back inverted symmetrical shape. That is, the cutting insert 3 is a so-called vertical blade double-sided type cutting insert. A pair of a first surface 11, a second surface 12, and a third surface 13 are provided on the outer surface of the insert body 10. The peripheral surface of the insert body 10 has four surfaces arranged in the circumferential direction (the direction around the central axis of the through hole 16). The four faces are a pair of second faces 12 and a pair of third faces 13. The second surface 12 and the third surface 13 are arranged alternately in the circumferential direction.
The configuration of the insert body 10 other than the above will be described later separately.

[Definition of direction (orientation) used in this embodiment (Explanation 2)]
In the present embodiment, the central axis of the through hole 16 is referred to as the first axis C1. The first axis C1 extends in the thickness direction of the insert body 10. The direction parallel to the first axis C1 (direction along the first axis C1) is the direction of the first axis C1 (direction of the central axis of the through hole 16). The direction of the first axis C1 corresponds to the thickness direction of the insert body 10. The first axis C1 passes through each center of the pair of first surfaces 11.

The second axis C2 passes through the peripheral surface of the insert body 10 and is orthogonal to the first axis C1. The second axis C2 passes through each center of the pair of second surfaces 12. The direction parallel to the second axis C2 (the direction along the second axis C2) is the second axis C2 direction. The second axis C2 direction is a direction orthogonal to the first axis C1 direction.

The third axis C3 passes through the peripheral surface of the insert body 10 and is orthogonal to the first axis C1. The third axis C3 passes through each center of the pair of third surfaces 13. The direction parallel to the third axis C3 (the direction along the third axis C3) is the third axis C3 direction. The third axis C3 direction is orthogonal to the first axis C1 direction and is different from the second axis C2 direction. In the example of this embodiment, the insert main body 10 has a rectangular plate shape, and the third axis C3 and the second axis C2 are orthogonal to each other. Therefore, the third axis C3 direction is also a direction orthogonal to the second axis C2 direction.

The first axis C1 and the second axis C2 intersect at a predetermined point inside the insert body 10. The first axis C1 and the third axis C3 intersect at a predetermined point inside the insert body 10. The second axis C2 and the third axis C3 intersect at a predetermined point inside the insert body 10. The predetermined point is the center (center point) of the insert body 10. The three axes C1, the second axis C2, and the third axis C3 intersect (orthogonally) with each other at the center of the insert body 10.

Of the first axis C1 directions, the direction from the first surface 11 toward the center of the insert body 10 is called the inside of the insert in the first axis C1 direction, and the direction from the center of the insert body 10 toward the first surface 11 is the first. It is called the outside of the insert in the uniaxial C1 direction.
Of the second axis C2 directions, the direction from the second surface 12 toward the center of the insert body 10 is called the inside of the insert in the second axis C2 direction, and the direction from the center of the insert body 10 toward the second surface 12 is the second. It is called the outside of the insert in the 2-axis C2 direction.
Of the third axis C3 directions, the direction from the third surface 13 toward the center of the insert body 10 is called the inside of the insert in the third axis C3 direction, and the direction from the center of the insert body 10 toward the third surface 13 is the third. It is called the outside of the insert in the 3-axis C3 direction.

[Insert body (Explanation 2)]
The insert body 10 has a 180 ° rotationally symmetric shape centered on the first axis C1. The insert body 10 has a 180 ° rotationally symmetric shape centered on the second axis C2. The insert body 10 has a 180 ° rotationally symmetric shape centered on the third axis C3.

The first surface 11 is a polygonal surface. The first surface 11 faces the direction of the first axis C1, and the pair of first surfaces 11 are arranged back to back with each other. Each first surface 11 faces the outside of the insert in the direction of the first axis C1. The second surface 12 faces the second axis C2 direction, and the pair of second surfaces 12 are arranged back to back with each other. Each second surface 12 faces the outside of the insert in the second axis C2 direction. The third surface 13 faces the third axis C3 direction, and the pair of third surfaces 13 are arranged back to back with each other. Each third surface 13 faces the outside of the insert in the third axis C3 direction.

The first surface 11 connects a pair of second surfaces 12 to each other, and connects a pair of third surfaces 13 to each other. The second surface 12 connects a pair of first surfaces 11 to each other, and connects a pair of third surfaces 13 to each other. The third surface 13 connects a pair of first surfaces 11 to each other and a pair of second surfaces 12 to each other.

The distance between the pair of first surfaces 11 in the first axis C1 direction is smaller than the distance between the pair of second surfaces 12 in the second axis C2 direction. The distance between the pair of first surfaces 11 in the first axis C1 direction is smaller than the distance between the pair of third surfaces 13 in the third axis C3 direction. Therefore, the insert main body 10 has a plate shape in which the direction of the first axis C1 is the thickness direction (plate thickness direction). Further, the distance between the pair of second surfaces 12 in the second axis C2 direction is smaller than the distance between the pair of third surfaces 13 in the third axis C3 direction. That is, the distance between the pair of first surfaces 11 in the first axis C1 direction, the distance between the pair of second surfaces 12 in the second axis C2 direction, and the distance between the pair of third surfaces 13 in the third axis C3 direction are , It is increased in this order.

[Blade]
The cutting edge 5 is arranged on the outer peripheral edge of the second surface 12. The cutting edge 5 is formed at the intersecting ridge line portion of the second surface 12, the first surface 11 and the third surface 13. The cutting edge 5 is located at a portion located at the intersecting ridge line between the first surface 11 and the second surface 12 (main cutting edge portion 14 described later) and at the intersecting ridge line between the second surface 12 and the third surface 13. It has a portion (secondary cutting edge portion 15 described later). That is, the cutting edge 5 has a portion located at the intersecting ridge line portion of the peripheral surface of the insert main body 10 and the first surface 11.

The cutting edge 5 is substantially L-shaped when viewed from the direction of the second axis C2. Two sets of L-shaped cutting edges 5 are provided on the outer peripheral edge of one second surface 12. On the outer peripheral edge of one second surface 12, the two sets of cutting edges 5 are arranged at 180 ° rotationally symmetric positions with respect to the second axis C2. In the example of this embodiment, a total of four sets of cutting edges 5 are provided on the cutting insert 3.

The cutting edge 5 has a main cutting edge portion 14, a sub cutting edge portion 15, a corner cutting edge portion 21, and a connecting blade portion 22. The blade length of the main cutting edge portion 14 is longer than the blade length of the sub cutting edge portion 15, the blade length of the corner blade portion 21, and the blade length of the connecting blade portion 22. The blade length of the sub-cutting blade portion 15 is longer than the blade length of the corner blade portion 21 and the blade length of the connecting blade portion 22. The blade length of the corner blade portion 21 is longer than the blade length of the connecting blade portion 22. For example, when the radius of curvature of the corner blade portion 21 is large, the blade length of the corner blade portion 21 may be longer than the blade length of the sub-cutting blade portion 15.

The main cutting edge portion 14 is formed at the intersecting ridge line portion between the first surface 11 and the second surface 12. The main cutting edge portion 14 extends linearly. The main cutting edge portion 14 is located on the long side of the four sides (a pair of long sides and a pair of short sides) forming the outer peripheral edge of the second surface 12.

As shown in FIG. 9, in the main cutting edge portion 14, the end portions of both ends of the main cutting edge portion 14 connected to the corner blade portion 21 are arranged on the outermost side of the insert in the second axis C2 direction. The main cutting edge portion 14 is an end portion of both ends of the main cutting edge portion 14 that is different from the end portion connected to the corner blade portion 21 to the end portion connected to the corner blade portion 21 (connection of other cutting edges 5). The end portion connected to the blade portion 22) is inclined toward the inside of the insert in the second axis C2 direction along the third axis C3 direction.

As shown in FIG. 8, in the main cutting edge portion 14, the end portions of both ends of the main cutting edge portion 14 connected to the corner blade portion 21 are arranged inside the insert in the first axis C1 direction. The main cutting edge portion 14 is an end portion of both ends of the main cutting edge portion 14 that is different from the end portion connected to the corner blade portion 21 to the end portion connected to the corner blade portion 21 (connection of other cutting edges 5). The end portion connected to the blade portion 22) is inclined toward the outside of the insert in the direction of the first axis C1 and extends toward the third axis C3 direction.

The secondary cutting edge portion 15 is formed at the intersecting ridge line portion between the second surface 12 and the third surface 13. The secondary cutting edge portion 15 is located on the short side of the four sides (a pair of long sides and a pair of short sides) forming the outer peripheral edge of the second surface 12. As shown in FIG. 8, when the cutting insert 3 is viewed from the second axis C2 direction (the second surface 12 is viewed from the front), the auxiliary cutting edge portion 15 is convex toward the outside of the insert in the third axis C3 direction. It is a V-shape.

The secondary cutting edge portion 15 has a first secondary cutting edge portion 31 and a second secondary cutting edge portion 32.
As shown in FIGS. 9 and 10, the first sub cutting edge portion 31 extends linearly. The first sub cutting edge portion 31 functions as a shaving blade during cutting. Specifically, when the cutting insert 3 is mounted on the insert mounting seat 4 of the tool body 2, the first secondary cutting edge portion 31 extends on a virtual plane (not shown) perpendicular to the tool axis O. The first sub-cutting edge portion 31 has an end portion connected to the corner blade portion 21 and an end portion connected to the second sub-cutting edge portion 32.

As shown in FIG. 8, when the cutting insert 3 is viewed from the second axis C2 direction, the first sub cutting edge portion 31 is the end portion of both ends of the first sub cutting edge portion 31 that is connected to the corner blade portion 21. Is placed inside the insert most in the third axis C3 direction. The first sub-cutting edge portion 31 is an end portion (second sub-cutting edge portion) of both ends of the first sub-cutting edge portion 31 that is different from the end portion connected to the corner blade portion 21 to the end portion connected to the corner blade portion 21. The end portion connected to the cutting edge portion 32) is inclined toward the outside of the insert in the direction of the third axis C3 along the direction toward the first axis C1.

As shown in FIG. 10, when the cutting insert 3 is viewed from the third axis C3 direction (when the third surface 13 is viewed from the front), the first sub cutting edge portion 31 is both ends of the first sub cutting edge portion 31. Of these, the end portion connected to the corner blade portion 21 is arranged on the outermost side of the insert in the second axis C2 direction. The first sub-cutting edge portion 31 is an end portion (second sub-cutting edge portion) of both ends of the first sub-cutting edge portion 31 that is different from the end portion connected to the corner blade portion 21 to the end portion connected to the corner blade portion 21. The end portion connected to the cutting edge portion 32) is inclined toward the inside of the insert in the second axis C2 direction along the direction toward the first axis C1.

As shown in FIGS. 9 and 10, the second secondary cutting edge portion 32 extends in a concave curve shape. The second sub cutting edge portion 32 functions as a ramping blade during cutting. Specifically, when the cutting insert 3 is mounted on the insert mounting seat 4 of the tool body 2, the second sub cutting edge portion 32 moves inward in the tool radial direction from the connection portion with the first sub cutting edge portion 31. As it faces, it inclines and extends toward the rear end of the tool. The second sub cutting edge portion 32 has an end portion connected to the first sub cutting edge portion 31 and an end portion connected to the connecting blade portion 22.

As shown in FIG. 8, when the cutting insert 3 is viewed from the second axis C2 direction, the second secondary cutting edge portion 32 is connected to the first secondary cutting edge portion 31 of both ends of the second secondary cutting edge portion 32. The end portion to be formed is arranged on the outer side of the insert in the direction of the third axis C3. The second sub cutting edge portion 32 is different from the end portion of both ends of the second sub cutting edge portion 32 connected to the first sub cutting edge portion 31 to the end portion connected to the first sub cutting edge portion 31. It is inclined toward the end (the end connected to the connecting blade 22) toward the inside of the insert in the direction of the third axis C3 along the direction of the first axis C1.

As shown in FIG. 10, when the cutting insert 3 is viewed from the third axis C3 direction, the second secondary cutting edge portion 32 is connected to the first secondary cutting edge portion 31 of both ends of the second secondary cutting edge portion 32. The end portion to be formed is arranged on the outer side of the insert in the direction of the second axis C2. The second sub cutting edge portion 32 is different from the end portion of both ends of the second sub cutting edge portion 32 connected to the first sub cutting edge portion 31 to the end portion connected to the first sub cutting edge portion 31. The end portion (the end portion connected to the connecting blade portion 22) is inclined toward the inside of the insert in the second axis C2 direction along the direction toward the first axis C1.

The second secondary cutting edge portion 32 has a portion of the cutting edge 5 located inside the insert in the second axis C2 direction. The portion of the second secondary cutting edge portion 32 located most inside the insert in the second axis C2 direction is located between both end portions of the second secondary cutting edge portion 32.

Of the secondary cutting edge portions 15, the connecting portion between the first secondary cutting edge portion 31 and the second secondary cutting edge portion 32 passes through the center of the cutting insert 3 and is on a virtual plane (not shown) perpendicular to the first axis C1. To position. That is, the connecting portion between the first secondary cutting edge portion 31 and the second secondary cutting edge portion 32 of the secondary cutting edge portion 15 is arranged at the center in the thickness direction (first axis C1 direction) of the cutting insert 3.
As shown in FIG. 8, when the cutting insert 3 is viewed from the direction of the second axis C2, the connecting portion between the first secondary cutting edge portion 31 and the second secondary cutting edge portion 32 is the most third axis C3 in the cutting edge 5. Located on the outside of the insert in the direction.

As shown in FIGS. 8 and 9, the corner blade portion 21 extends in a convex curve shape. The corner blade portion 21 is arranged at the corner portion located between the main cutting edge portion 14 and the first sub cutting edge portion 31 among the four corner portions on the outer peripheral edge of the second surface 12, and the main cutting edge portion 21 is arranged. It is connected to the portion 14 and the first secondary cutting edge portion 31. The corner blade portion 21 is in contact with the main cutting edge portion 14 and the first sub cutting edge portion 31, and smoothly connects the main cutting edge portion 14 and the first sub cutting edge portion 31.
As shown in FIGS. 9 and 10, the corner blade portion 21 has a portion of the cutting edge 5 located on the outer side of the insert in the second axis C2 direction.

As shown in FIG. 8, the connecting blade portion 22 extends in a convex curve shape. The connecting blade portion 22 is different from the second auxiliary cutting edge portion 32 and the one cutting edge 5 including the second secondary cutting edge portion 32 among the four corner portions of the outer peripheral edge of the second surface 12. It is arranged at a corner portion located between the main cutting edge portion 14 of the cutting edge 5 and is connected to the second secondary cutting edge portion 32 and the main cutting edge portion 14 of the other cutting edge 5. The connecting blade portion 22 connects a pair of cutting blades 5 adjacent to each other around the second axis C2 on the outer peripheral edge of the second surface 12. Since the connecting blade portion 22 is a fake cutting edge 5 portion that is generally not used for cutting, it does not have to be provided on the cutting edge 5.

[First side]
The first surface 11 is a plate surface facing the thickness direction of the plate-shaped cutting insert 3. The first surface 11 has a rectangular shape. As shown in FIG. 9, when the cutting insert 3 is viewed from the direction of the first axis C1 (when the first surface 11 is viewed from the front), the first surface 11 has a parallel quadrilateral shape. The length of the first surface 11 in the direction of the third axis C3 is larger than the length in the direction of the second axis C2. The first surface 11 has a flank portion (main flank portion 23, which will be described later) of the main cutting edge portion 14 among the flanks of the cutting edge 5.

The first surface 11 has a main flank surface portion 23 and a radial seating surface portion 24.
The main flank portion 23 extends along the main cutting edge portion 14. The main flank portion 23 is connected to the main cutting edge portion 14. The main flank portion 23 is located inside the main cutting edge portion 14 on the first surface 11. A pair of main flanks 23 are provided at both ends of the first surface 11 in the second axis C2 direction. The width of the main flank portion 23 is maximum at the connection portion between the main cutting edge portion 14 and the corner blade portion 21. The width of the main flank 23 decreases from the connection portion between the main cutting edge portion 14 and the corner blade portion 21 toward the connection portion between the main cutting edge portion 14 and the connecting blade portion 22 of the other cutting edge 5. .. As shown in FIGS. 10 and 11, the main flank portion 23 is inclined toward the outside of the insert in the first axis C1 direction as it is separated from the main cutting edge portion 14 in the second axis C2 direction.

The radial seating surface portion 24 has a planar shape perpendicular to the first axis C1. The radial seating surface portion 24 is located between the pair of main flank surface portions 23 on the first surface 11. The main flank portion 23 may not be provided on the first surface 11. In this case, the radial seating surface portion 24 is directly connected to the main cutting edge portion 14.

[Through hole]
The through hole 16 extends inside the insert body 10 in the direction of the first axis C1. The through hole 16 penetrates the cutting insert 3 in the direction of the first axis C1 and opens in each radial seating surface portion 24 of the pair of first surfaces 11. A screw member 20 is inserted into the through hole 16 (see FIG. 1 and the like). As shown in FIG. 12, the through hole 16 has a circular cross section perpendicular to the first axis C1.

As shown in FIG. 11, the through hole 16 has a large diameter portion 17, a small diameter portion 18, and a tapered portion 19.
The large diameter portion 17 is located at the end of the insert body 10 in the first axis C1 direction. The large diameter portion 17 is located at the end of the through hole 16 in the direction of the first axis C1. A pair of large diameter portions 17 are provided at both ends of the through hole 16 in the direction of the first axis C1. The large diameter portion 17 opens to the first surface 11. The large diameter portion 17 has the largest inner diameter in the through hole 16.

The large diameter portion 17 has an outer large diameter portion 17a and an inner large diameter portion 17b.
The outer large diameter portion 17a is connected to the outer surface of the insert body 10. The outer large diameter portion 17a is connected to the first surface 11 of the outer surface of the insert body 10. The outer large diameter portion 17a is connected to the radial seating surface portion 24. As shown in FIG. 11, the outer large diameter portion 17a extends substantially linearly in a cross-sectional view perpendicular to the third axis C3. In the example of the present embodiment, the inner diameter of the outer large diameter portion 17a becomes smaller as it goes from the radial seating surface portion 24 toward the inside of the insert in the first axis C1 direction. The inner diameter of the outer large diameter portion 17a may be constant in the direction of the first axis C1.

The inner large diameter portion 17b is located inside the insert in the first axis C1 direction with respect to the outer large diameter portion 17a. The inner large diameter portion 17b connects the outer large diameter portion 17a and the first curved surface portion 19a of the tapered portion 19, which will be described later (see FIGS. 13 and 14). In the cross-sectional view shown in FIG. 11, the inner large diameter portion 17b extends in a concave curved shape.

The inner large diameter portion 17b has a third curved surface portion 17c. As shown in FIG. 14, the third curved surface portion 17c has a concave curved shape in a cross section (longitudinal cross section) including the first axis C1. Specifically, in the vertical cross-sectional view shown in FIG. 14, the third curved surface portion 17c has a concave arc shape. The third curved surface portion 17c may be paraphrased as a concave curved surface portion 17c. In the example of the present embodiment, the third curved surface portion 17c is arranged over the entire area of the inner large diameter portion 17b in the direction of the first axis C1. Therefore, the third curved surface portion 17c connects the outer large diameter portion 17a and the first curved surface portion 19a described later.

The third curved surface portion 17c is connected to the outer large diameter portion 17a and the first curved surface portion 19a so as to be in smooth contact with each other. In the vertical cross section shown in FIG. 14, the third curved surface portion 17c and the outer large diameter portion 17a have a common tangent line at the connection portion with each other. The third curved surface portion 17c and the first curved surface portion 19a have a common tangent line at the connecting portion with each other.

The diameter of the third curved surface portion 17c is reduced from the connecting portion between the third curved surface portion 17c and the outer large diameter portion 17a toward the inside of the insert in the direction of the first axis C1. That is, in FIG. 13, the third curved surface portion 17c is separated from the connecting portion between the third curved surface portion 17c and the outer large diameter portion 17a in the direction of the first axis C1 and is located inside the insert in the direction of the second axis C2 and the third. It is inclined and extends toward the inside of the insert in the axis C3 direction. The inner diameter of the third curved surface portion 17c becomes smaller toward the inside of the insert in the direction of the first axis C1.

The small diameter portion 18 has a smaller diameter than the large diameter portion 17. The small diameter portion 18 has the smallest inner diameter in the through hole 16. The small diameter portion 18 is located inside the insert in the first axis C1 direction with respect to the large diameter portion 17. The small diameter portion 18 is arranged away from the large diameter portion 17 inside the insert in the direction of the first axis C1. The inner diameter of the small diameter portion 18 is substantially constant in the direction of the first axis C1. The inner diameter of the small diameter portion 18 increases slightly from the center of the insert body 10 (the intersection of the first axis C1, the second axis C2, and the third axis C3) toward the outside of the insert in the first axis C1 direction. The inner diameter of the small diameter portion 18 may be constant in the direction of the first axis C1. The center of the insert body 10 is located inside the small diameter portion 18. The inner peripheral surface of the small diameter portion 18 intersects the second axis C2 and the third axis C3.

The tapered portion 19 connects the large diameter portion 17 and the small diameter portion 18. A pair of tapered portions 19 are provided between the pair of large diameter portions 17 and the small diameter portions 18. The tapered portion 19 is located inside the insert in the first axis C1 direction with respect to the large diameter portion 17. The tapered portion 19 is connected to the large diameter portion 17 from the inside of the insert in the direction of the first axis C1. The tapered portion 19 is located outside the insert in the first axis C1 direction with respect to the small diameter portion 18. The tapered portion 19 is connected to the small diameter portion 18 from the outside of the insert in the direction of the first axis C1. The diameter of the tapered portion 19 is reduced from the connecting portion between the tapered portion 19 and the large diameter portion 17 toward the inside of the insert in the first axis C1 direction. The inner diameter of the tapered portion 19 decreases toward the inside of the insert in the direction of the first axis C1.

As shown in FIGS. 13 and 14, the tapered portion 19 has a first curved surface portion 19a and a second curved surface portion 19b.
The first curved surface portion 19a is connected to the large diameter portion 17. The first curved surface portion 19a is connected to the third curved surface portion 17c of the inner large diameter portion 17b. As shown in FIG. 14, the first curved surface portion 19a has a convex curved shape in a cross section including the first axis C1. Specifically, in the vertical cross-sectional view shown in FIG. 14, the first curved surface portion 19a has a convex arc shape. In this vertical cross section, the radius of curvature of the first curved surface portion 19a is smaller than the radius of curvature of the third curved surface portion 17c.

The diameter of the first curved surface portion 19a is reduced from the connecting portion between the first curved surface portion 19a and the third curved surface portion 17c toward the inside of the insert in the direction of the first axis C1. That is, the first curved surface portion 19a is separated from the connecting portion between the first curved surface portion 19a and the third curved surface portion 17c in the first axis C1 direction, and is inside the insert in the second axis C2 direction and in the third axis C3 direction. It slopes and extends toward the inside of the insert. The inner diameter of the first curved surface portion 19a becomes smaller toward the inside of the insert in the direction of the first axis C1.

The second curved surface portion 19b is located inside the insert in the first axis C1 direction with respect to the first curved surface portion 19a. The second curved surface portion 19b is connected to the first curved surface portion 19a from the inside of the insert in the direction of the first axis C1. The second curved surface portion 19b is located outside the insert in the first axis C1 direction with respect to the small diameter portion 18. The second curved surface portion 19b is connected to the small diameter portion 18 from the outside of the insert in the direction of the first axis C1.

As shown in FIG. 14, the shape of the cross section of the second curved surface portion 19b including the first axis C1 is a convex curve. Specifically, in the vertical cross-sectional view shown in FIG. 14, the second curved surface portion 19b has a convex arc shape. In this vertical cross section, the radius of curvature of the second curved surface portion 19b is larger than the radius of curvature of the first curved surface portion 19a and the radius of curvature of the third curved surface portion 17c.

The second curved surface portion 19b is connected so as to be in smooth contact with the first curved surface portion 19a. In the vertical cross section shown in FIG. 14, the second curved surface portion 19b and the first curved surface portion 19a have a common tangent line at the connection point P which is a connection portion between the second curved surface portion 19b and the first curved surface portion 19a. In this vertical cross section, the connection point P between the first curved surface portion 19a and the second curved surface portion 19b is arranged outside the insert in the first axis C1 direction with respect to the center position in the tapered portion 19 in the first axis C1 direction.

The diameter of the second curved surface portion 19b is reduced from the connection point P toward the inside of the insert in the direction of the first axis C1. That is, the second curved surface portion 19b is inclined and extends toward the inside of the insert in the direction of the second axis C2 and the inside of the insert in the direction of the third axis C3 so as to be separated from the connection point P in the direction of the first axis C1. The inner diameter of the second curved surface portion 19b becomes smaller toward the inside of the insert in the direction of the first axis C1.

[Second side]
As shown in FIG. 7, the second surface 12 is connected to the first surface 11. The second surface 12 is connected to the pair of first surfaces 11. The second surface 12 is connected to the long side of the four sides (a pair of long sides and a pair of short sides) forming the outer peripheral edge of the first surface 11. The second surface 12 has a rectangular shape. As shown in FIG. 8, the second surface 12 has a rectangular shape when viewed from the direction of the second axis C2. The length of the second surface 12 in the direction of the third axis C3 is larger than the length in the direction of the first axis C1.

The second surface 12 has a rake surface of the cutting edge 5. The rake face of the cutting edge 5 includes a rake face portion of the main cutting edge portion 14, a rake face portion of the sub cutting edge portion 15, a rake face portion of the corner blade portion 21, and a rake face portion of the connecting blade portion 22. Has. The rake face is arranged adjacent to the cutting edge 5. The rake face is connected to the cutting edge 5. The rake face extends along the cutting edge 5. Since the cutting insert 3 of the present embodiment is a vertical blade type, the rake surface is arranged on the peripheral surface of the insert body 10. In the example of this embodiment, the rake face is arranged on the second surface 12 of the peripheral surfaces.

The second surface 12 has a land portion 25, an inclined surface portion 26, a convex portion 33, and a flat surface portion 27.
The land portion 25 projects from the second surface 12 in the direction of the second axis C2. The land portion 25 projects outward from the insert in the second axis C2 direction on the second surface 12. The land portion 25 is arranged inside the cutting edge 5 on the second surface 12. The land portion 25 extends along the cutting edge 5. The land portion 25 is connected to the cutting edge 5 from the inside of the second surface 12 over the entire length of the cutting edge 5.

As shown in FIG. 8, the land portion 25 is substantially L-shaped when viewed from the direction of the second axis C2. Two sets of L-shaped land portions 25 are provided on one second surface 12. The two sets of land portions 25 are arranged at 180 ° rotationally symmetric positions with respect to the second axis C2. The two sets of land portions 25 are connected to each other around the second axis C2. The overall shape of the two sets of land portions 25 is a rectangular frame shape.

The land portion 25 is a rake face of the cutting edge 5. The land portion 25 has a rake face portion of the main cutting edge portion 14, a rake face portion of the sub cutting edge portion 15, a rake face portion of the corner blade portion 21, and a rake face portion of the connecting blade portion 22. The rake face portion of the main cutting edge portion 14 is located inside the main cutting edge portion 14 on the second surface 12. The rake face portion of the secondary cutting edge portion 15 is located inside the secondary cutting edge portion 15 on the second surface 12. The rake face portion of the corner blade portion 21 is located inside the corner blade portion 21 on the second surface 12. The rake face portion of the connecting blade portion 22 is located inside the connecting blade portion 22 on the second surface 12. When the connecting blade portion 22 is not used for cutting, the rake face portion of the connecting blade portion 22 may not have a function as a rake face.

The land portion 25 is inclined toward the inside of the insert in the second axis C2 direction from the cutting edge 5 toward the inside of the second surface 12. The width of the land portion 25 (the length in the direction orthogonal to the cutting edge 5) is the maximum in the portion where the land portion 25 is connected to the corner blade portion 21.
Of the land portion 25, a portion connected to the main cutting edge portion 14, a portion connected to the corner blade portion 21, and a portion connected to the first sub cutting edge portion 31 are planar. Of the land portion 25, the portion connected to the second secondary cutting edge portion 32 and the portion connected to the connecting blade portion 22 have a concave curved surface shape.

The inclined surface portion 26 is located inside the land portion 25 on the second surface 12. The inclined surface portion 26 is connected to the land portion 25 from the inside of the second surface 12. The inclined surface portion 26 extends along the land portion 25. Of the inclined surface portion 26, the portion of the second surface 12 located inside the main cutting edge portion 14, the portion located inside the corner blade portion 21, and the portion located inside the first sub cutting edge portion 31 are From the connecting portion between the inclined surface portion 26 and the land portion 25, the surface is inclined toward the inside of the second surface 12 and toward the inside of the insert in the second axis C2 direction.

Of the inclined surface portion 26, the portion of the second surface 12 located inside the main cutting edge portion 14 has an inclination angle with respect to a virtual plane (not shown) perpendicular to the second axis C2, which is the second surface of the land portion 25. 12 is larger than the inclination angle of the portion located inside the main cutting edge portion 14. Of the inclined surface portion 26, the portion located inside the corner blade portion 21 on the second surface 12 has an inclination angle with respect to a virtual plane (not shown) perpendicular to the second axis C2, and the second surface 12 of the land portion 25 has an inclination angle. Is larger than the inclination angle of the portion located inside the corner blade portion 21. Of the inclined surface portion 26, the portion of the second surface 12 located inside the first secondary cutting edge portion 31 has an inclination angle with respect to a virtual plane (not shown) perpendicular to the second axis C2, which is the second of the land portions 25. It is larger than the inclination angle of the portion located inside the first secondary cutting edge portion 31 on the two surfaces 12.

The convex portion 33 projects from the second surface 12 in the second axis C2 direction. In the example of the present embodiment, the convex portion 33 protrudes in the second axis C2 direction from the portion of the second surface 12 located inside the insert in the second axis C2 direction (the flat surface portion 27 described later).

As shown in FIG. 8, the through hole 16 and the convex portion 33 are arranged so as to overlap each other when viewed from the direction of the second axis C2. When viewed from the second axis C2 direction, the convex portion 33 has a portion that overlaps with at least the large diameter portion 17. The convex portion 33 has a portion of the large diameter portion 17 that overlaps at least the inner large diameter portion 17b. In the example of the present embodiment, the convex portion 33 overlaps the large diameter portion 17, the small diameter portion 18, and the tapered portion 19 when viewed from the direction of the second axis C2.

When viewed from the second axis C2 direction, the convex portion 33 is arranged inside the through hole 16 in the third axis C3 direction. That is, when viewed from the second axis C2 direction, both ends of the convex portion 33 in the third axis C3 direction are located inside the insert in the third axis C3 direction than both ends of the through hole 16 in the third axis C3 direction. The convex portion 33 is arranged in the through hole 16 when viewed from the second axis C2 direction. The length (width) of the convex portion 33 in the third axis C3 direction is smaller than the length of the through hole 16 in the third axis C3 direction.

The convex portion 33 extends on the second surface 12 in the direction of the first axis C1. The length of the convex portion 33 in the first axis C1 direction is larger than the length of the convex portion 33 in the third axis C3 direction. The end portion of the convex portion 33 in the direction of the first axis C1 is connected to the land portion 25. In the example of this embodiment, both ends of the convex portion 33 in the direction of the first axis C1 are connected to the pair of land portions 25. The end portion of the convex portion 33 in the direction of the first axis C1 is connected to the inclined surface portion 26. In the example of this embodiment, both ends of the convex portion 33 in the direction of the first axis C1 are connected to the inclined surface portion 26, respectively.

As shown in FIG. 8, when viewed from the direction of the second axis C2, the convex portion 33 has the maximum amount of protrusion from the second surface 12 at the portion overlapping the first axis C1. When viewed from the second axis C2 direction, the portion of the convex portion 33 located on the first axis C1 protrudes most from the flat surface portion 27, which will be described later, toward the second axis C2 direction.

When viewed from the second axis C2 direction, the convex portion 33 protrudes from the second surface 12 as it is separated from the portion overlapping the first axis C1 in the third axis C3 direction (see FIG. 12). That is, when viewed from the second axis C2 direction, the convex portion 33 inclines and extends toward the inside of the insert in the second axis C2 direction from above the first axis C1 toward the third axis C3 direction.

As shown in FIG. 12, in the cross section perpendicular to the first axis C1 direction, the through hole 16 has a circular shape, and the outer surface of the convex portion 33 is centered on the first axis C1 which is the central axis of the through hole 16. It is arcuate. That is, in this cross-sectional view, the convex portion 33 has an arc shape that is convex toward the outside of the insert in the second axis C2 direction.

The convex portion 33 has an outer portion 34 and an inner portion 35.
A pair of outer portions 34 are provided at both ends of the convex portion 33 in the direction of the first axis C1. The outer portion 34 is located at the end of the convex portion 33 in the first axis C1 direction. When viewed from the second axis C2 direction, the outer portion 34 is arranged so as to overlap the large diameter portion 17 and the tapered portion 19. The outer portion 34 of the convex portion 33 is a portion that overlaps at least the large diameter portion 17 when viewed from the second axis C2 direction.

The outer portion 34 is connected to the land portion 25. As shown in FIG. 11, the outer portion 34 is inclined and extends toward the inside of the insert in the second axis C2 direction so as to be separated from the connection portion between the outer portion 34 and the land portion 25 in the first axis C1 direction. The amount of protrusion of the outer portion 34 from the second surface 12 (flat surface portion 27) toward the second axis C2 is the largest at the connection portion between the outer portion 34 and the land portion 25, and the first axis from this connection portion. It becomes smaller toward the inside of the insert in the C1 direction.

When viewed from the second axis C2 direction, the outer portion 34 protrudes from the second surface 12 as it is separated from the portion overlapping the first axis C1 in the third axis C3 direction (see FIG. 12). That is, when viewed from the second axis C2 direction, the outer portion 34 is inclined and extends toward the inside of the insert in the second axis C2 direction from above the first axis C1 toward the third axis C3 direction.

The inner portion 35 is located between both ends of the convex portion 33 in the first axis C1 direction. The inner portion 35 connects a pair of outer portions 34 to each other. When viewed from the direction of the second axis C2, the inner portion 35 is arranged so as to overlap the small diameter portion 18 and the tapered portion 19. The inner portion 35 of the convex portion 33 is a portion that overlaps at least the small diameter portion 18 when viewed from the second axis C2 direction. That is, when viewed from the direction of the second axis C2, the convex portion 33 has a portion that overlaps the small diameter portion 18.

The amount of protrusion of the inner portion 35 from the second surface 12 (flat surface portion 27) toward the second axis C2 direction is constant in the first axis C1 direction. As shown in FIG. 11, of the convex portion 33, the amount of protrusion of the outer portion 34 from the second surface 12 toward the second axis C2 is the second surface of the inner portion 35 toward the second axis C2. It is larger than the amount of protrusion from 12.

As shown in FIG. 8, the inner portion 35 extends on the second surface 12 in the direction of the first axis C1. The length (width) of the inner portion 35 in the third axis C3 direction is constant in the first axis C1 direction. Of the convex portion 33, the length of the outer portion 34 in the third axis C3 direction is larger than the length of the inner portion 35 in the third axis C3 direction.

When viewed from the second axis C2 direction, the inner portion 35 protrudes from the second surface 12 as the distance from the portion overlapping the first axis C1 in the third axis C3 direction (see FIG. 12). That is, when viewed from the second axis C2 direction, the inner portion 35 is inclined and extends toward the inside of the insert in the second axis C2 direction from above the first axis C1 toward the third axis C3 direction.

More specifically, as shown in FIG. 8, when viewed from the second axis C2 direction, the convex portion 33 has a portion 33a overlapping the large diameter portion 17, a portion 33b overlapping the small diameter portion 18, and a portion overlapping the tapered portion 19. It has 33c and. The portion 33a overlapping the large diameter portion 17 is arranged on the outer portion 34. The portion 33b overlapping the small diameter portion 18 is arranged in the inner portion 35. The portion 33c overlapping the tapered portion 19 includes a portion located on the outer portion 34 and a portion located on the inner portion 35. That is, the portion 33c overlapping the tapered portion 19 is arranged over the outer portion 34 and the inner portion 35.

As shown in FIG. 11, the amount of protrusion of the portion 33a overlapping the large diameter portion 17 from the second surface 12 toward the second axis C2 of the convex portion 33 is the second of the portion 33b overlapping the small diameter portion 18. It is larger than the amount of protrusion from the second surface 12 toward the axis C2 and the amount of protrusion of the portion 33c overlapping the tapered portion 19 from the second surface 12 toward the second axis C2.
When viewed from the second axis C2 direction, the length of the portion 33c of the convex portion 33 overlapping the tapered portion 19 in the third axis C3 direction is larger than the length of the portion 33b overlapping the small diameter portion 18 in the third axis C3 direction. big.

The flat surface portion 27 is located on both sides of the convex portion 33 in the third axis C3 direction on the second surface 12. In the example of this embodiment, a pair of flat surface portions 27 are provided on both sides of the convex portions 33 on the second surface 12. The flat surface portion 27 has a substantially quadrangular shape. In the example of this embodiment, the flat surface portion 27 extends in a direction perpendicular to the second axis C2.

[Third side]
As shown in FIG. 7, the third surface 13 is connected to the first surface 11 and the second surface 12. The third surface 13 is connected to the pair of first surfaces 11 and the pair of second surfaces 12. The third surface 13 is connected to the short side of the four sides (a pair of long sides and short sides) forming the outer peripheral edge of the first surface 11. The third surface 13 is connected to the short side of the four sides forming the outer peripheral edge of the second surface 12. The third surface 13 has a rectangular shape. As shown in FIG. 10, the third surface 13 has a parallel quadrilateral shape when viewed from the third axis C3 direction. The length of the third surface 13 in the direction of the second axis C2 is larger than the length in the direction of the first axis C1. The third surface 13 has a flank portion of the sub-cutting edge portion 15 (sub flank surface portion 36 described later) among the flanks of the cutting edge 5.

The third surface 13 has a secondary flank portion 36. A pair of secondary flanks 36 are provided on one third surface 13. The pair of secondary flanks 36 face each other in the second axis C2 direction. The pair of secondary flanks 36 are connected to each other in the second axis C2 direction.

The secondary flank portion 36 has a first sub flank surface portion 41 and a second sub flank surface portion 42.
The first sub flank portion 41 is connected to the first sub cutting edge portion 31. The first secondary flank portion 41 is located inside the first secondary cutting edge portion 31 on the third surface 13. The first secondary flank surface portion 41 has a convex curved surface shape. The first secondary flank surface portion 41 may be flat. The first secondary flank portion 41 extends from the first secondary cutting edge portion 31 in the direction of the second axis C2. The length (width) of the first secondary flank surface portion 41 in the first axis C1 direction becomes smaller as it goes toward the inside of the insert in the second axis C2 direction.

The second secondary flank portion 42 is connected to the second secondary cutting edge portion 32. The second secondary flank portion 42 is located inside the second secondary cutting edge portion 32 on the third surface 13. The second secondary flank surface portion 42 is planar. The second secondary flank portion 42 extends from the second secondary cutting edge portion 32 in the direction of the second axis C2. The length (width) of the second secondary flank portion 42 in the first axis C1 direction becomes smaller as it is separated from the second secondary cutting edge portion 32 in the second axis C2 direction.

The first sub flank surface portion 41 and the second sub flank surface portion 42 of the sub flank surface portion 36 are connected in the direction of the first axis C1. As shown in FIG. 8, the second secondary flank surface portion 42 is located in the third axis C1 direction (outside the insert) from the connection portion between the second secondary flank surface portion 42 and the first secondary flank surface portion 41. Tilt toward the inside of the insert in the axis C3 direction. That is, as shown in FIG. 8, when viewed from the second axis C2 direction, the second secondary flank surface portion 42 is located inside the insert in the third axis C3 direction as it is separated from the third axis C3 in the first axis C1 direction. Extend towards.

As shown in FIG. 10, the length of the second secondary flank surface portion 42 in the second axis C2 direction is larger than the length of the first secondary flank surface portion 41 in the second axis C2 direction. The length (width) of the second secondary flank surface portion 42 in the first axis C1 direction is larger than the length of the first secondary flank surface portion 41 in the first axis C1 direction.

[Insert mounting seat (Explanation 2)]
As shown in FIGS. 4 to 6, the insert mounting seat 4 has a first wall portion 51, a second wall portion 52, a third wall portion 53, and a screw hole 54.
The first wall portion 51 faces the outside in the tool radial direction in the insert mounting seat 4. The first wall portion 51 is planar. The first wall portion 51 has a substantially quadrangular shape. When the cutting insert 3 is attached to the insert mounting seat 4, the first wall portion 51 comes into contact with the first surface 11. The first wall portion 51 comes into contact with the radial seating surface portion 24 of the first surface 11.

The second wall portion 52 faces the tool rotation direction T in the insert mounting seat 4. When the cutting insert 3 is attached to the insert mounting seat 4, the second wall portion 52 comes into contact with the second surface 12.

The second wall portion 52 has a support portion 52a and a recess 52b.
The support portion 52a is planar. The support portion 52a has a substantially quadrangular shape or a substantially pentagonal shape. A pair of support portions 52a are provided on the second wall portion 52 at intervals in the tool axis O direction. The support portion 52a supports a portion of the second surface 12 other than the convex portion 33. In the example of this embodiment, the support portion 52a supports the flat surface portion 27. The pair of support portions 52a of the second wall portion 52 come into contact with the pair of flat surface portions 27 of the second surface 12.

The recess 52b is recessed from the second wall portion 52 in the direction opposite to the tool rotation direction T. The recess 52b is recessed from the support portion 52a in the anti-tool rotation direction. The recess 52b has a groove shape extending in the radial direction of the tool. The convex portion 33 is inserted into the concave portion 52b. A convex portion 33 is arranged in the concave portion 52b. The inner surface of the concave portion 52b and the outer surface of the convex portion 33 face each other with a gap.

The third wall portion 53 faces the tool tip side in the insert mounting seat 4. The third wall portion 53 is planar. The third wall portion 53 has a substantially pentagonal shape. When the cutting insert 3 is attached to the insert mounting seat 4, the third wall portion 53 comes into contact with the third surface 13. The third wall portion 53 comes into contact with the second secondary flank surface portion 42 of the third surface 13. The third wall portion 53 comes into contact with the second secondary flank surface portion 42 located outside in the tool radial direction among the pair of second secondary flank surface portions 42 of the third surface 13.

The screw hole 54 opens in the first wall portion 51. The screw hole 54 extends inward in the tool radial direction from the first wall portion 51. A female screw portion is provided on the inner peripheral surface of the screw hole 54.

[Screw member and cutting insert screw structure]
As shown in FIGS. 1 and 2, the screw member 20 fixes the cutting insert 3 to the insert mounting seat 4. The screw member 20 is inserted into the through hole 16 and screwed into the insert mounting seat 4. The screw member 20 is a commercially available product or the like, and has a general shape.
The screwing structure 8 of the cutting insert 3 of the present embodiment includes a cutting insert 3, an insert mounting seat 4, and a screw member 20 (see FIGS. 13 and 14). In FIG. 13, the insert mounting seat 4 is not shown. The central axis of the screw member 20 substantially coincides with the central axis of the through hole 16. That is, the central axis of the screw member 20 is substantially coaxial with the first axis C1 and extends along the first axis C1.

As shown in FIGS. 13 and 14, the screw member 20 has a screw shaft portion 29 and a screw head portion 30.
The screw shaft portion 29 is inserted into the through hole 16. The screw shaft portion 29 extends in the direction of the first shaft C1. The outer diameter of the screw shaft portion 29 is smaller than the inner diameter of the small diameter portion 18. The screw shaft portion 29 has a male screw portion 29a. The male screw portion 29a is formed on the outer peripheral surface of the screw shaft portion 29. The male screw portion 29a is provided on a portion of the outer peripheral surface of the screw shaft portion 29 other than the end portion on the screw head 30 side in the first axis C1 direction. The screw shaft portion 29 is screwed into the insert mounting seat 4 on which the cutting insert 3 is arranged. That is, the male screw portion 29a of the screw shaft portion 29 is screwed into the female screw portion of the screw hole 54.

The screw head 30 has a larger diameter than the screw shaft portion 29. That is, the outer diameter of the screw head 30 is larger than the outer diameter of the screw shaft portion 29. The screw head 30 is connected to the screw shaft portion 29 from the outside of the insert in the direction of the first shaft C1. At least a portion of the screw head 30 is inserted into the through hole 16. In the example of this embodiment, the entire screw head 30 is arranged in the through hole 16. The screw head 30 comes into contact with the inner peripheral surface of the through hole 16. The screw head 30 comes into contact with the tapered portion 19.

As shown in FIG. 14, the screw head 30 has a head large diameter portion 30a, a head taper portion 30b, and a head ridge line portion 30c.
The large diameter portion 30a of the head has the largest outer diameter in the screw head 30. The head large diameter portion 30a is arranged at the end of the screw head 30 on the outer side of the insert in the direction of the first axis C1. The outer diameter of the head large diameter portion 30a is smaller than the inner diameter of the large diameter portion 17. The large-diameter portion 30a of the head and the large-diameter portion 17 face each other with a distance in the direction (diametrical direction) orthogonal to the first axis C1.

The head tapered portion 30b is located inside the insert in the first axis C1 direction with respect to the head large diameter portion 30a. The head tapered portion 30b is connected to the head large diameter portion 30a from the inside of the insert in the direction of the first axis C1. The outer diameter of the head tapered portion 30b decreases from the head large diameter portion 30a toward the inside of the insert in the first axis C1 direction. The diameter of the head tapered portion 30b is reduced from the head large diameter portion 30a toward the screw shaft portion 29 along the first axis C1 direction. In the vertical cross section including the first axis C1 (central axis of the screw member 20), the head tapered portion 30b is a linear shape extending in an inclined manner with respect to the first axis C1.

The head tapered portion 30b comes into contact with the tapered portion 19. The head tapered portion 30b contacts at least the connection point P between the first curved surface portion 19a and the second curved surface portion 19b. The head tapered portion 30b also contacts a portion of the second curved surface portion 19b located inside the insert in the first axis C1 direction of the connection point P. That is, the head tapered portion 30b also contacts the portion of the second curved surface portion 19b adjacent to the inside of the insert in the first axis C1 direction of the connection point P.

The head ridge line portion 30c is located at the intersection ridge line portion between the head large diameter portion 30a and the head taper portion 30b. The head ridge line portion 30c is an annular shape extending around the first axis C1. The head ridge line portion 30c has a circular shape centered on the first axis C1. The head ridge line portion 30c faces the first curved surface portion 19a. The head ridge line portion 30c is arranged with a gap between it and the first curved surface portion 19a.

[Mounting posture of cutting insert on insert mounting seat]
When the cutting insert 3 is mounted on the insert mounting seat 4, the second axis C2 of the cutting insert 3 is inclined and extends toward the tool tip side in the tool rotation direction T, although not particularly shown. The third axis C3 is inclined and extends in a direction opposite to the tool rotation direction T as it is directed toward the tool tip side.

[Action and effect of this embodiment]
According to the cutting insert 3 of the present embodiment described above, the screwing structure 8 of the cutting insert 3, and the cutting tool 1 with a replaceable cutting edge, the following effects can be obtained.
In the present embodiment, the tapered portion 19 of the through hole 16 has a convex curved first curved surface portion 19a and a convex curved first curved surface portion 19a in a cross-sectional view including the first axis C1 (the central axis of the through hole 16). It has a second curved surface portion 19b having a radius of curvature larger than the radius of curvature of the curved surface portion 19a. That is, in this cross-sectional view, the connection point P between the first curved surface portion 19a and the second curved surface portion 19b is an inflection point at which the radius of curvature of the tapered portion 19 changes.

According to the present embodiment, the following effects can be obtained by bringing the head tapered portion 30b of the screw member 20 into contact with the tapered portion 19 of the through hole 16.
In the vertical cross-sectional view of the through hole 16, the tapered portion 19 has a convex curve shape as a whole. That is, the tapered portion 19 has a convex curved shape as a whole while including two convex curved first curved surface portions 19a and a second curved surface portion 19b having different radii of curvature. Therefore, it is possible to prevent the tapered portion 19 and the head tapered portion 30b from making surface contact (so-called solid contact) as a whole. Therefore, the contact position between the tapered portion 19 and the head tapered portion 30b in the first axis C1 direction is stable, and the cutting insert 3 is stably fixed to the insert mounting seat 4 by the screw member 20.

Then, if the head tapered portion 30b is brought into contact with the connection point P between at least the first curved surface portion 19a and the second curved surface portion 19b of the tapered portion 19, it is in the direction of the first axis C1 with respect to the connection point P. In the region located on the outer side of the insert, the contact between the head ridge line portion 30c and the first curved surface portion 19a can be suppressed.
Specifically, since the radius of curvature of the first curved surface portion 19a is smaller than the radius of curvature of the second curved surface portion 19b, the first curved surface portion 19a has a screw head on the outside of the insert in the direction of the first axis C1 from the connection point P. It is easy to separate from the portion 30. Since the head ridge portion 30c of the screw head 30 is convex and angular, when it is brought into contact with the inner peripheral surface of the through hole 16, chamfer-like wear progresses at an early stage, and the cutting insert 3 is fixed. Becomes unstable. On the other hand, according to the present embodiment, since the head ridge line portion 30c can be easily separated from the inner peripheral surface of the through hole 16, the progress of wear of the screw head 30 is suppressed, and the fixed state of the cutting insert 3 is good. Is maintained at.

Further, in the region located inside the insert in the direction of the first axis C1 with respect to the connection point P, a large contact area between the head tapered portion 30b and the second curved surface portion 19b can be secured.
Specifically, since the radius of curvature of the second curved surface portion 19b is larger than the radius of curvature of the first curved surface portion 19a, the second curved surface portion 19b has a screw head inside the insert in the direction of the first axis C1 from the connection point P. It is easy to come into contact with the portion 30. As a result, a large contact area between the inner peripheral surface of the through hole 16 and the screw head 30 can be secured, and the fixed state of the cutting insert 3 by the screw member 20 is stabilized. Further, the progress of wear of the screw head 30 is suppressed, and the fixed state of the cutting insert 3 is maintained well.

From the above, according to the present embodiment, the cutting insert 3 can be fixed without using a special structure for the screw member 20, the wear of the screw member 20 can be suppressed, and the fixed state of the cutting insert 3 can be maintained satisfactorily.

Further, in the present embodiment, in the vertical cross-sectional view of the through hole 16, the first curved surface portion 19a and the second curved surface portion 19b have a common tangent line at the connection point P of each other (that is, they are in contact with each other). Differently, the progress of partial wear of the screw member 20 is suppressed as compared with the case where the connection point P is formed in a convex shape, for example.

Further, in the present embodiment, in the vertical cross-sectional view of the through hole 16, the connection point P is arranged outside the insert in the first axis C1 direction from the center position in the taper portion 19 in the first axis C1 direction. Action effect is obtained.
In this case, the connection point P can be arranged at a position close to the large diameter portion 17 in the tapered portion 19. Therefore, the portion of the head taper portion 30b that contacts the connection point P also has a large outer diameter at the head taper portion 30b, so that the fixed state of the cutting insert 3 by the screw member 20 is more stable. That is, a large contact area (contact peripheral length) between the inner peripheral surface of the through hole 16 and the screw member 20 around the first axis C1 is secured, and the diameter of the contact position is also large, so that the cutting insert 3 wobbles and the like. Is easy to suppress.

Further, in the present embodiment, since the inner large-diameter portion 17b of the large-diameter portion 17 has the concave curved third curved surface portion 17c in the vertical cross-sectional view of the through hole 16, the following effects can be obtained.
In this case, the large diameter portion 17 and the tapered portion 19 of the through hole 16 are smoothly connected by the third curved surface portion 17c of the large diameter portion 17. Therefore, it is possible to secure the strength near the corner angle (recess) of the connecting portion between the large diameter portion 17 and the tapered portion 19, which tends to be low inside the through hole 16, and the rigidity of the cutting insert 3 is increased. Further, according to the above configuration, it is easy to form the shape of the through hole 16 at the time of manufacturing.

In the case of the vertical blade type cutting insert 3 as in the present embodiment, the screw member 20 receives a cutting load from a direction orthogonal to the central axis of the screw member 20 (screw radial direction) during cutting. Therefore, the outer diameter of the screw shaft portion 29 is set large for the purpose of ensuring the rigidity of the screw member 20, and the inner diameter of the through hole 16 is increased accordingly, making it difficult to secure the wall thickness around the through hole 16. .. Therefore, by providing the third curved surface portion 17c in the through hole 16 as in the present embodiment, the rigidity of the cutting insert 3 can be ensured, and the effect of suppressing breakage can be obtained. Note that "breakage" is a phenomenon in which a crack occurs between the outer surface of the cutting insert 3 and the through hole 16 and the cutting insert 3 is cracked (damaged).

Further, in the present embodiment, the insert body 10 has a plate shape. As described above, when the cutting insert 3 has a plate shape, the cutting insert 3 may easily wobble during cutting, but according to the present embodiment, the cutting insert 3 is stably fixed by the screw member 20. , The fixed state of the cutting insert 3 is well maintained.

Further, in the present embodiment, the cutting insert 3 is a vertical blade type. Generally, in the vertical blade type cutting insert 3, since the screw member 20 receives a cutting load from the radial direction of the screw during cutting, the fixed state of the cutting insert 3 tends to be unstable. According to this, the cutting insert 3 is stably fixed by the screw member 20, and the fixed state of the cutting insert 3 is maintained well.

Further, in the present embodiment, the insert main body 10 has a front-back inverted symmetrical shape. That is, since the cutting insert 3 has an inverted symmetrical shape, even if the cutting insert 3 is turned upside down and used, the same effect as described above can be obtained. The number of cutting edges 5 of the cutting insert 3 is doubled, and the tool life is extended.

[Other configurations included in the present invention]
The present invention is not limited to the above-described embodiment, and the configuration can be changed without departing from the spirit of the present invention, for example, as described below.

In the above-described embodiment, the third curved surface portion 17c is arranged over the entire area of the inner large diameter portion 17b in the direction of the first axis C1, and the third curved surface portion 17c is formed on the outer large diameter portion 17a and the first curved surface portion 19a. I gave an example of connection, but it is not limited to this. For example, the third curved surface portion 17c may be arranged in a portion (part) of the inner large diameter portion 17b in the direction of the first axis C1. Further, the third curved surface portion 17c may be connected to only one of the outer large diameter portion 17a and the first curved surface portion 19a.

Further, an example is given in which the radius of curvature of the third curved surface portion 17c is larger than the radius of curvature of the first curved surface portion 19a and smaller than the radius of curvature of the second curved surface portion 19b, but the present invention is not limited to this. The radius of curvature of the third curved surface portion 17c may be smaller than the radius of curvature of the first curved surface portion 19a. The radius of curvature of the third curved surface portion 17c may be larger than the radius of curvature of the second curved surface portion 19b.

In the above-described embodiment, the vertical blade type cutting insert 3 in which the rake face (that is, the land portion 25) of the cutting edge 5 is arranged on the peripheral surface (second surface 12) of the insert body 10 will be described as an example. However, it is not limited to this. The present invention may be applied to a horizontal blade type cutting insert in which the rake face of the cutting edge is arranged on a plate surface (corresponding to the first surface 11) facing the thickness direction of the insert body.

In the above-described embodiment, the insert body 10 has a quadrangular plate shape, but the present invention is not limited to this. The insert main body 10 may have a polygonal plate shape such as a triangular plate shape, a pentagonal plate shape, a hexagonal plate shape, and a heptagonal plate shape. Further, the insert body 10 may have a disk shape.

In the above-described embodiment, the insert body 10 has a front-back inverted symmetrical shape, but the present invention is not limited to this. That is, the cutting insert 3 is not limited to the double-sided type, but may be a single-sided type.

In addition, as long as it does not deviate from the gist of the present invention, each configuration (component) described in the above-described embodiments, modifications, and notes may be combined, and additions, omissions, substitutions, and the like of the configurations may be combined. It can be changed. Further, the present invention is not limited to the above-described embodiments, but is limited only to the scope of claims.

3 ... Cutting insert 4 ... Insert mounting seat 5 ... Cutting edge 8 ... Screwing structure of cutting insert 10 ... Insert body 16 ... Through hole 17 ... Large diameter part 17a ... Outer large diameter part 17b ... Inner large diameter part 17c ... Third Curved surface portion 19 ... Tapered portion 19a ... First curved surface portion 19b ... Second curved surface portion 20 ... Screw member 29 ... Screw shaft portion 29a ... Male screw portion 30 ... Screw head 30a ... Head large diameter portion 30b ... Head tapered portion 30c ... Head ridge C1 ... First axis (central axis of through hole)
P ... Connection point

Claims (7)

Insert body and
With a through hole penetrating the insert body,
The through hole is
A large diameter portion located at the end of the through hole in the central axial direction and having the largest inner diameter in the through hole.
The large-diameter portion has a tapered portion that is connected from the inside of the insert in the central axis direction and whose inner diameter decreases toward the inside of the insert in the central axis direction.
The tapered portion is
A first curved surface portion connected to the large diameter portion and having a convex curved cross section including the central axis, and a first curved surface portion.
It is connected to the first curved surface portion from the inside of the insert in the central axis direction, and the shape of the cross section including the central axis is a convex curve shape, and the radius of curvature is larger than the radius of curvature of the first curved surface portion in this cross section. It has a second curved surface and
A cutting insert having a common tangent at a connection point between the first curved surface portion and the second curved surface portion in a cross section including the central axis . Insert body and
With a through hole penetrating the insert body,
The through hole is
A large diameter portion located at the end of the through hole in the central axial direction and having the largest inner diameter in the through hole.
The large-diameter portion has a tapered portion that is connected from the inside of the insert in the central axis direction and whose inner diameter decreases toward the inside of the insert in the central axis direction.
The tapered portion is
A first curved surface portion connected to the large diameter portion and having a convex curved cross section including the central axis, and a first curved surface portion.
It is connected to the first curved surface portion from the inside of the insert in the central axis direction, and the shape of the cross section including the central axis is a convex curve shape, and the radius of curvature is larger than the radius of curvature of the first curved surface portion in this cross section. It has a second curved surface and
The large diameter part is
The outer large diameter part connected to the outer surface of the insert body,
It has an inner large diameter portion connecting the outer large diameter portion and the first curved surface portion, and has an inner large diameter portion.
The inner large diameter portion is a cutting insert having a third curved surface portion having a concave curved cross section including the central axis. The cutting insert according to claim 1 or 2.
In the cross section including the central axis, the connection point between the first curved surface portion and the second curved surface portion is arranged outside the insert in the central axis direction with respect to the central position in the tapered portion in the central axis direction. Cutting insert. The cutting insert according to any one of claims 1 to 3 .
The insert body is plate-shaped and has a plate shape.
The through hole is a cutting insert that opens to a pair of plate surfaces on the outer surface of the insert body. The cutting insert according to claim 4 .
A cutting edge having a peripheral surface connecting a pair of the plate surfaces of the outer surface of the insert body and a portion located at an intersecting ridge line portion of the plate surface.
A cutting insert comprising a rake face adjacent to the cutting edge and disposed on the peripheral surface. The cutting insert according to any one of claims 1 to 5 .
The insert body is a cutting insert having a front-back inverted symmetrical shape. A cutting insert comprising an insert body and a through hole penetrating the insert body .
An insert mounting seat to which the cutting insert can be attached and detached, and
A screwing structure for a cutting insert comprising a screw member inserted into the through hole and screwed into the insert mounting seat.
The through hole is
A large diameter portion located at the end of the through hole in the central axial direction and having the largest inner diameter in the through hole.
The large-diameter portion has a tapered portion that is connected from the inside of the insert in the central axis direction and whose inner diameter decreases toward the inside of the insert in the central axis direction.
The tapered portion is
A first curved surface portion connected to the large diameter portion and having a convex curved cross section including the central axis, and a first curved surface portion.
It is connected to the first curved surface portion from the inside of the insert in the central axis direction, and the shape of the cross section including the central axis is a convex curve shape, and the radius of curvature is larger than the radius of curvature of the first curved surface portion in this cross section. It has a second curved surface and
The screw member is
A screw shaft portion extending in the central axis direction and having a male screw portion,
It has a larger diameter than the screw shaft portion, and has a screw head connected to the screw shaft portion from the outside of the insert in the central axis direction.
The screw head
The large diameter part of the head, which has the largest outer diameter in the screw head,
A head taper portion that is connected to the head large diameter portion from the inside of the insert in the central axis direction and whose outer diameter becomes smaller toward the inside of the insert in the central axis direction from the head large diameter portion.
It has a head ridge line portion located at an intersection ridge line portion between the head large diameter portion and the head taper portion.
The head tapered portion is in contact with at least the connection point between the first curved surface portion and the second curved surface portion.
The head ridge portion is a screwed structure of a cutting insert, which is arranged with a gap between the head ridge portion and the first curved surface portion.

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