JP2019093497A - Cutting insert and blade edge replaceable type rotary cutting tool - Google Patents

Abstract

To allow a material to be cut to be subjected to cutting processing so that an aspect of a processed surface is made even regardless of a processing site to be processed and a shape, of the material.SOLUTION: A cutting blade part 4 comprises: a bottom cutting blade 11, arranged at a tip part in a center shaft C direction of an insert main body 15, which extends along a radial direction orthogonal to the center shaft C and forms a circular-arc shape protruding toward a tip side in the center shaft C direction; an outer peripheral cutting blade 9, arranged at an outer end part in the radial direction of the insert main body 15, which extends along the center shaft C direction and forms a circular-arc shape protruding toward outside in the radial direction; and a rake surface 19. An outer end A in the radial direction of the bottom cutting blade 11 and a tip B in the center shaft C direction of the outer peripheral cutting blade 9 connect to each other through a linear cutting blade 13 or directly, and cross each other at an angle α of 45° with respect to the center shaft C in a front view of the rake surface 19. The bottom cutting blade 11 and the outer peripheral cutting blade 9 are formed to be line-symmetric with each other, with a virtual straight line VL extending toward the tip side in the center shaft C direction as going toward outside in the radial direction set as an axis of symmetry.SELECTED DRAWING: Figure 7

Description

  TECHNICAL FIELD The present invention relates to a cutting insert suitable for performing face facing processing (flat surface processing), side surface cutting processing (vertical wall surface processing), and the like on a work material, and an edge-exchange-type rotating cutting tool equipped with the same.

Conventionally, solid type end mills as shown, for example, in the following patent documents 1 and 2 are known. An end mill of this type comprises a shank rotated about a central axis, and a cutting edge formed at the tip of the shank. Further, among the cutting edge portions, a bottom cutting edge having an arc shape that is convex toward the tip end side is disposed at the tip end portion in the central axis direction, and at the outer end portion in the radial direction An outer peripheral cutting edge having an arc shape that is convex toward the end is disposed.
The bottom cutting edge is used when face milling (planar processing) is performed on the work material, and the outer peripheral cutting edge is used when side milling (vertical wall processing) is performed. .

Japanese Patent Publication No. 2010-520064 Unexamined-Japanese-Patent No. 2007-152502

However, the above-described conventional end mill has the following problems.
When subjecting a work material to face milling processing, the grain (cutting point, processing marks) imparted to the machined surface by cutting with the bottom cutting edge, and when cutting the side surface It was difficult to finish the same texture as that of the stitches applied to the machined surface by cutting with a blade. That is, the properties of the machined surface after cutting vary depending on the machined portion and shape of the work material, and the machining accuracy of the whole machined surface can not be made uniform in finishing, semi-finishing, and the like.

  The present invention has been made in view of such circumstances, and is a cutting insert capable of performing cutting so that the properties of the machined surface become uniform regardless of the machined part or shape of the work material An object of the present invention is to provide an indexable rotary cutting tool using the same.

One aspect of the present invention is a cutting insert detachably mounted on a mounting seat formed on a tip of a tool body which is rotated about a central axis, and a plate-like insert body and the insert body A cutting edge portion formed, wherein the cutting edge portion is disposed at a tip end portion in the central axis direction of the insert body and extends along a radial direction orthogonal to the central axis, and the central axis And an arc-shaped bottom cutting edge that is convex toward the front end side of the direction, and is disposed at the radially outer end of the insert body and extends along the central axis direction, and the radially outer side An outer peripheral cutting edge having a circular arc shape convex toward the surface, and a rake surface, wherein the radial outer end of the bottom cutting edge and the tip of the outer peripheral cutting edge in the central axial direction are straight lines Direct connection via cutting edge When the rake face is viewed from the front, it intersects at an angle of 45 ° with the central axis, and a virtual straight line extending toward the distal end in the central axial direction as it goes outward in the radial direction is a symmetry axis. It is characterized in that the bottom cutting edge and the outer peripheral cutting edge are formed in line symmetry with each other.
Further, according to one aspect of the present invention, there is provided a cutting insert detachably mounted on a mounting seat formed at a tip end portion of a tool main body rotated about a central axis, wherein the insert main body has a plate shape; A cutting edge portion formed in the main body, the cutting edge portion being disposed at a tip end portion in the central axis direction of the insert main body, and extending along a radial direction orthogonal to the central axis; A bottom cutting edge having an arc shape that is convex toward the tip end side in the central axis direction, and is disposed at the outer end of the radial direction of the insert body and extends along the central axis direction, and the radial direction And a rake surface, the radius of curvature of the bottom cutting edge and the radius of curvature of the outer cutting edge being identical to each other, the bottom Said radial direction of the cutting edge The end and the tip of the outer peripheral cutting edge in the direction of the central axis are directly connected via a straight cutting edge, and the rake surface is viewed from the front, passing the tip of the bottom cutting edge in the direction of the central axis The straight line extending along the radial direction is a radial reference line, and the straight line extending along the central axis direction through the radial outer end of the outer peripheral cutting edge is a central axial direction reference line The tangent of the bottom cutting edge at the radially outer end is a first tangent, the tangent of the outer cutting edge at the tip of the outer peripheral cutting edge in the central axis direction is a second tangent, and the first tangent Connecting the point of intersection of the axis with the radial direction reference line, the point of intersection of the first tangent with the center axis direction reference line, and the point of intersection of the diameter direction reference line with the center axis direction reference line Let the right triangle formed be the first right triangle, The intersection point of the second tangent line and the central axis direction reference line, the intersection point of the second tangent line and the radial direction reference line, and the intersection point of the radial direction reference line and the central axis direction reference line, The first right triangle and the second right triangle are congruent with each other, wherein a second right triangle formed by connecting straight lines to each other is a second right triangle.
Further, according to one aspect of the present invention, there is provided a tool body which is rotated about a central axis, a mounting seat formed at a tip end portion of the tool body, and a cutting insert detachably mounted on the mounting seat. It is a blade-tip-exchange-type rotary cutting tool, characterized in that the above-mentioned cutting insert is used as the cutting insert.

Further, in the cutting insert, a screw insertion hole is formed in the insert main body so as to penetrate the insert main body in a thickness direction, and a hole center of the screw insertion hole is positioned on the virtual straight line. Is preferred.
Further, in the cutting insert, a screw insertion hole is formed in the insert main body so as to penetrate the insert main body in the thickness direction, and the hole center of the screw insertion hole is the radial direction of the bottom cutting edge. The middle point of the line connecting the outer end and the tip of the outer peripheral cutting edge in the central axis direction or the connection point between the outer end and the tip and the intersection point of the radial direction reference line and the center axis direction reference line It is preferable to be located on a virtual straight line passing through and.

  Further, in the cutting insert, it is preferable that the outer end in the radial direction of the bottom cutting edge and the tip in the central axis direction of the outer peripheral cutting edge be connected via the one linear cutting edge.

  Further, in the cutting insert, it is preferable that the outer end in the radial direction of the bottom cutting edge and the tip in the central axis direction of the outer peripheral cutting edge be connected via a plurality of straight cutting edges.

  Further, in the cutting insert, the outer end in the radial direction of the bottom cutting edge and the tip in the central axis direction of the outer peripheral cutting edge are connected via the linear cutting edge, and among the rake surfaces, It is preferable that the rake surface portion of the bottom cutting edge, the rake surface portion of the outer peripheral cutting edge, and the raking surface portion of the straight cutting edge are formed on the same plane.

  In the cutting insert, the radial outer end of the bottom cutting edge and the tip of the outer peripheral cutting edge in the central axial direction are directly connected, and the rake face of the bottom cutting edge among the rake faces. It is preferable that the portion and the rake face portion of the peripheral cutting edge are formed on the same plane.

  Further, in the cutting insert, a straight line extending along the radial direction passing through the tip in the central axial direction of the bottom cutting edge as a radial direction reference line when the rake surface is viewed from the front as the radial direction reference line The tangent of the bottom cutting edge at the outer end in the radial direction is taken as a first tangent, and the tangent of the outer cutting edge at the tip of the outer peripheral cutting edge in the central axis direction is taken as a second tangent. The angle θ1 formed between the radial reference line is 10 to 30 °, and the angle θ2 formed between the second tangent and the radial reference line is (90 ° -θ1 It is preferred that it is) °.

  In the cutting insert, it is preferable that an axial rake angle of the outer peripheral cutting edge has a positive value, and an axial rake angle of the bottom cutting edge has a positive value.

  According to the cutting insert and the blade-tip-exchange-type rotary cutting tool of the present invention, it is possible to perform cutting so that the properties of the processing surface become uniform regardless of the processing site or shape of the work material. Therefore, in the finishing process, the semi-finishing process and the like, it is possible to obtain good machined surface accuracy over the entire machined surface.

It is a perspective view which shows the blade-tip-exchange-type rotary cutting tool of 1st Embodiment of this invention. It is a top view of a blade-tip-exchange-type rotation cutting tool. It is a side view of a blade-tip-exchange-type rotary cutting tool. It is a front view of a blade-tip-exchange-type rotary cutting tool. It is a perspective view which shows the cutting insert of 1st Embodiment. It is a (a) top view which shows a cutting insert, (b) Side view, (c) It is a front view. It is a (a) top view which expands and shows the cutting-blade part of a cutting insert, (b) Side view, (c) It is a front view. It is the top view of the cutting insert of 1st Embodiment which looked at the rake face to the front. It is the top view of the cutting insert of the reference example which looked at the rake face to the front. It is the top view of the cutting insert of the reference example which looked at the rake face to the front. (A) A diagram showing the pick feed pitch and cusp height of the machined surface cut with the cutting insert according to the present invention (a cutting edge exchange type rotary cutting tool), (b) the pitch of the pick feed of the machined surface cut with a conventional cutting tool and It is a figure which shows cusp height. It is a perspective view which shows the blade-tip-exchange-type rotary cutting tool of 2nd Embodiment of this invention. It is a perspective view which shows the cutting insert of 2nd Embodiment. It is a (a) top view which expands and shows the cutting-blade part of a cutting insert, (b) Side view, (c) It is a front view. It is a perspective view which shows the blade-tip-exchange-type rotary cutting tool of 3rd Embodiment of this invention. It is a perspective view which shows the cutting insert of 3rd Embodiment. It is a (a) top view which expands and shows the cutting-blade part of a cutting insert, (b) Side view, (c) It is a front view. It is a perspective view which shows the blade-tip-exchange-type rotary cutting tool of 4th Embodiment of this invention. It is a perspective view which shows the cutting insert of 4th Embodiment. It is a (a) top view which expands and shows the cutting-blade part of a cutting insert, (b) Side view, (c) It is a front view. It is the (a) top view which shows the modification of the cutting insert of the embodiment of the present invention, the (b) side view, and the (c) front view.

First Embodiment
Hereinafter, a cutting insert 5A according to a first embodiment of the present invention and an indexable rotary cutting tool 6A provided with the same will be described with reference to FIGS. In the drawings used for describing the embodiments, in order to make features of the present invention intelligible, the main parts may be enlarged, emphasized or extracted.

  The cutting insert 5A of this embodiment connects the bottom cutting edge 11 of a convex arc shape called a so-called lens, the outer peripheral cutting edge 9 of a convex arc shape called a so-called barrel, and the bottom cutting edge 11 and the outer peripheral cutting edge 9 And a composite cutting edge configured of a straight cutting edge 13 having a linear shape. And, the blade-tip-exchange-type rotary cutting tool 6A provided with the cutting insert 5A performs various cutting processes including face-cutting (flat surface processing) and side surface cutting (vertical wall surface processing) on a work material. It is suitable, and in particular, it is possible to obtain an excellent surface accuracy in finishing, semi-finishing, etc. of the machined surface.

  As shown in FIGS. 1 to 4, the indexable rotary cutting tool 6 </ b> A includes a substantially cylindrical tool main body 1 rotated about a central axis C and a tip 2 in the central axis C direction of the tool main body 1. The formed mounting seat 3 and a cutting insert 5A detachably mounted on the mounting seat 3 and having a cutting edge 4 are provided.

  The blade-tip-exchange-type rotary cutting tool 6A of the present embodiment includes a tool body 1 formed of steel or the like, and a cutting insert 5A formed of cemented carbide or the like harder than the tool body 1. A plate-like cutting insert 5A is removable from the mounting seat (insert mounting seat) 3 formed at the tip 2 of the tool body 1 with the central axis of the insert aligned with the central axis C of the tool. It is attached. In the cutting insert 5A attached to the mounting seat 3, the cutting edge portion 4 is disposed so as to protrude to the tip end side of the tool body 1 and to the outside in the radial direction.

  In the indexable rotary cutting tool 6A, the base end portion (shank portion) of the tool main body 1 is attached to the main shaft (not shown) of the machine tool, and the main shaft is rotated about the central axis C. It is rotated in the tool rotation direction R. Then, the tool main body 1 is sent together with the main shaft in the direction crossing the central axis C or in the central axis C direction, thereby cutting a work material made of a metal material or the like with the cutting edge 4 of the cutting insert 5A. , Subject to milling (milling). In addition, it is more preferable to use for machine tools, such as a machining center of multi-axis control of 4 to 6 axes, for example, of the blade-tip-exchange-type rotary cutting tool 6A of the present embodiment.

  In the present embodiment, the direction in which the central axis C of the tool body 1 extends, that is, the direction along the central axis C, is referred to as the central axis C direction. In the central axis C direction, the direction (downward in FIGS. 2 and 3) from the shank portion of the tool body 1 to the mounting seat 3 is referred to as the tip side, and the direction from the mounting seat 3 toward the shank portion (FIG. The upper side in FIG. 3 is referred to as the proximal side.

In addition, a direction orthogonal to the central axis C is referred to as a radial direction. Among the radial directions, the direction approaching the central axis C is referred to as the inner side in the radial direction, and the direction separating from the central axis C is referred to as the outer side in the radial direction.
Moreover, the direction which revolves around the central axis C is called a circumferential direction. Of the circumferential direction, the direction in which the tool body 1 is rotated by the rotation of the spindle during cutting is called the tool rotation direction R, and the opposite rotation direction is the side opposite to the tool rotation direction R (that is, the opposite tool rotation direction). ).

  The definition of the direction (direction) described above is similarly applied to the cutting insert 5A in which the insert central axis is made coincident (coaxially disposed) with the central axis C of the indexable rotary cutting tool 6A. Ru. Therefore, in FIGS. 6 to 10 and the like showing the cutting insert 5A, the insert central axis is represented by using the same symbol C as the central axis C.

  In FIG. 1 to FIG. 4, the mounting seat 3 is a tip end portion 2 of the tool main body 1 and a slit-like insert fitting groove 7 which is formed to extend radially including the central axis C of the tool And a fixing screw 8 for fixing the cutting insert 5A inserted into the groove 7.

  The insert fitting groove 7 is opened in the tip end surface of the tool body 1, extends in the radial direction of the tool body 1, and is also opened in the outer peripheral surface of the tool body 1. The insert fitting groove 7 is in the form of a slit formed in a predetermined length (depth) from the distal end surface of the tool body 1 toward the proximal end.

  By forming the slit-like insert fitting groove 7 at the tip 2 of the tool body 1, the tip 2 of the tool body 1 is divided into two to form a pair of tip halves (half pieces) It is done. Further, an insert fixing screw hole is formed in the distal end portion 2 so as to intersect the insert fitting groove 7 and reach the inside of the other distal half portion from one surface portion of the distal half portion. The screw hole central axis of the insert fixing screw hole extends in the radial direction at the tip end portion 2, and specifically, the direction in which the insert fitting groove 7 extends in the radial direction of the tool body 1 in the radial direction. , Extends in the orthogonal direction.

  Of the insert fixing screw holes, the inner diameter of the hole portion formed in one tip half portion is larger than the inner diameter of the hole portion formed in the other tip half portion. Further, on the inner peripheral surface of the hole portion formed in the other tip half portion, a female screw portion to be screwed with the male screw portion of the fixing screw 8 is formed. The hole part formed in at least one tip half part among the insert fixing screw holes is a through hole. In the example of this embodiment, each hole part of one tip half part and the other tip half part is made into a penetration hole, respectively.

As shown in FIGS. 5 to 8, the cutting insert 5A is formed of a plate-like insert body 15, a cutting edge 4 formed on the insert body 15, and the insert body 15, and the insert body 15 is thick And a screw insertion hole 18 penetrating in the longitudinal direction.
The cutting insert 5A of the present embodiment is formed with front and back inversion symmetry (180 ° rotational symmetry) with the central axis C as a symmetry axis.

  The insert body 15 has a substantially flat shape. The front and back surfaces facing the thickness direction of the insert body 15 are a pair of flat portions 16 and 17. The screw insertion hole 18 is a through hole which penetrates the insert main body 15 in the thickness direction and is opened in one plane portion 16 and the other plane portion 17. The fixing screw 8 is inserted into the screw insertion hole 18 when the cutting insert 5A is mounted on the mounting seat 3 and fixed. The arrangement of the screw insertion holes 18 in the insert body 15 will be described later separately.

The cutting edge 4 is disposed at the tip of the insert body 15 in the central axis C direction and at the outer end in the radial direction. The cutting edge portion 4 has a rake face 19 facing in the tool rotational direction R, a flank face crossing the rake face 19 and facing at least one of the tip side and the radial outer side, and a crossing ridge line between the rake face 19 and the flank face And a cutting edge formed on the.
The cutting edges include an outer peripheral cutting edge 9, a bottom cutting edge 11, and a straight cutting edge 13. The cutting edge is substantially L-shaped as a whole by being provided with the outer peripheral cutting edge 9, the bottom cutting edge 11, and the straight cutting edge 13. In addition, a rake surface portion (10, 12, 14), which will be described later, of the rake surface 19 and a flank surface portion of the flank are adjacent to each cutting edge (9, 11, 13).

  The cutting insert 5A of the present embodiment is a two-edged cutting insert, and the set of cutting edges provided with the outer peripheral cutting edge 9, the bottom cutting edge 11, and the straight cutting edge 13 is 180 around the central axis C. There are two sets of rotational symmetry.

As shown in FIG. 7A, the bottom cutting edge 11 is disposed at the tip of the insert main body 15 in the central axis C direction, extends along the radial direction, and is directed toward the tip of the central axis C direction. It has an arc shape that is convex.
The bottom cutting edge 11 is inclined toward the tip side in the central axis C direction as it extends radially inward from the radial outer end (connection point) A of the bottom cutting edge 11 connected to the linear cutting edge 13 It extends. The amount of displacement of the bottom cutting edge 11 in the direction of the central axis C per unit length along the radial direction (that is, the inclination with respect to the radial direction) is from the radially outer end A of the bottom cutting edge 11 radially inward. It becomes smaller gradually as it goes toward zero and becomes zero at the radial inner end.

  Of the total length of the cutting edge of the cutting edge portion 4, the radially inner end of the bottom cutting edge 11 is located at the foremost end in the central axis C direction. In the present embodiment, the radially inner end of the bottom cutting edge 11 is disposed on the central axis C. A tangent (radial reference line described later) RR at the radially inner end (the forefront of the central axis C direction) of the bottom cutting edge 11 extends parallel to a plane (horizontal surface) perpendicular to the central axis C.

  When the cutting insert 5A is attached to the mounting seat 3 (insert fitting groove 7) of the tool main body 1 and the indexable rotary cutting tool 6A is rotated about the central axis C, the rotation trajectory of the bottom cutting edge 11 is the tip It has a convex lens shape that bulges out to the side.

  In the example of this embodiment, as shown in FIG. 7B, the axial rake angle (axial rake) of the bottom cutting edge 11 is 0 °. However, the invention is not limited to this, and the axial rake angle of the bottom cutting edge 11 may be a positive value (positive angle) or a negative value (negative angle). Moreover, as FIG.6 (c) and FIG.7 (c) show, the radial direction rake angle of the bottom cutting edge 11 is 0 degree.

As shown in FIG. 7A, of the rake face 19 of the cutting edge 4 facing the tool rotational direction R, the portion adjacent to the base end side in the central axis C direction of the bottom cutting edge 11 is a bottom cutting edge There are 11 rake face portions 12. In the example of the present embodiment, the rake surface portion 12 of the bottom cutting edge 11 is flat.
Further, of the tip surface of the insert body 15 facing the tip side in the central axis C direction, the portion adjacent to the side opposite to the tool rotation direction R of the bottom cutting edge 11 is the flank surface portion of the bottom cutting edge 11. The flank surface portion of the bottom cutting edge 11 has a curved surface shape which is convex toward the tip end side. The flank surface portion of the bottom cutting edge 11 is inclined toward the base end side in the central axis C direction from the bottom cutting edge 11 toward the opposite side to the tool rotational direction R, whereby the bottom cutting edge 11 Has a clearance angle.

As shown in FIG. 7A, the outer peripheral cutting edge 9 is disposed at the outer end of the insert body 15 in the radial direction, extends along the central axis C direction, and is convex outward in the radial direction. It has an arc shape that becomes
The outer peripheral cutting edge 9 extends radially outward as it goes from the tip (connection point) B in the direction of the central axis C of the outer peripheral cutting edge 9 connected to the linear cutting edge 13 to the proximal end side. . The amount of displacement of the outer peripheral cutting edge 9 in the radial direction per unit length along the central axis C direction (that is, the inclination with respect to the central axis C direction) is based on the tip B in the central axis C direction of the outer peripheral cutting edge 9 It becomes smaller gradually toward the end side and becomes zero at the proximal end in the central axis C direction.

  The base end of the outer peripheral cutting edge 9 in the central axis C direction in the entire cutting edge length of the cutting edge 4 is located at the outermost end in the radial direction. A tangent (a central axis direction reference line described later) CR at a base end (the outermost end in the radial direction) in the central axis C direction of the outer peripheral cutting edge 9 is parallel to a plane (vertical surface) parallel to the central axis C Extend.

  When the cutting insert 5A is attached to the mounting seat 3 of the tool main body 1 and the tip-exchange-type rotary cutting tool 6A is rotated about the central axis C, the rotation trajectory of the outer peripheral cutting edge 9 bulges outward in the radial direction Form a barrel shape (barrel shape).

  In the example of the present embodiment, as shown in FIG. 7B, the axial rake angle (corresponding to the twist angle) of the outer peripheral cutting edge 9 is 0 °. However, the present invention is not limited to this, and the axial rake angle of the outer peripheral cutting edge 9 may be a positive value or a negative value. The radial direction rake angle (central direction rake angle, radial rake) of the outer peripheral cutting edge 9 is 0 °. However, the present invention is not limited to this, and the radial direction rake angle of the outer peripheral cutting edge 9 may be a positive value or a negative value.

As shown in FIG. 7A, of the rake face 19 of the cutting edge 4 facing the tool rotational direction R, the portion adjacent to the radially inner side of the outer peripheral cutting edge 9 is the rake face portion of the outer peripheral cutting edge 9 10 In the example of the present embodiment, the rake surface portion 10 of the outer peripheral cutting edge 9 has a planar shape.
Further, of the outer peripheral surface of the insert body 15 facing radially outward, the portion adjacent to the side opposite to the tool rotation direction R of the outer peripheral cutting edge 9 is a flank surface portion of the outer peripheral cutting edge 9. The flank surface portion of the outer peripheral cutting edge 9 has a curved surface shape which is convex outward in the radial direction. The flank surface portion of the outer peripheral cutting edge 9 is inclined radially inward as it goes from the outer peripheral cutting edge 9 to the opposite side to the tool rotational direction R, whereby a clearance angle is given to the outer peripheral cutting edge 9 It is done.

  As shown in FIG. 7 (a), the straight cutting edge 13 has a straight shape. The straight cutting edge 13 connects the radially outer end A of the bottom cutting edge 11 and the tip B in the central axis C direction of the outer circumferential cutting edge 9. That is, the radially outer end A of the bottom cutting edge 11 and the tip B in the central axis C direction of the outer circumferential cutting edge 9 are connected via the linear cutting edge 13. In the present embodiment, the outer end A in the radial direction of the bottom cutting edge 11 and the tip B in the direction of the central axis C of the outer peripheral cutting edge 9 are connected via one linear cutting edge 13.

  The straight cutting edge 13 is inclined toward the base end in the central axis C direction as it goes radially outward from the radial inner end (connection point A) of the straight cutting edge 13 connected to the bottom cutting edge 11 It extends. The straight cutting edge 13 extends radially inward as it extends from the proximal end (connection point B) in the direction of the central axis C of the straight cutting edge 13 connected to the outer peripheral cutting edge 9 toward the distal end. .

  When the cutting insert 5A is mounted on the mounting seat 3 of the tool body 1 and the tip-exchange-type rotary cutting tool 6A is rotated about the central axis C, the rotation trajectory of the linear cutting edge 13 is toward the tip of the central axis C direction. It is formed in a tapered cylindrical shape whose diameter gradually decreases as it goes.

  In the example of the present embodiment, as shown in FIG. 7B, the axial direction rake angle of the straight cutting edge 13 is 0 °. Therefore, the axial direction rake angle of the straight cutting edge 13 at the connection point A between the straight cutting edge 13 and the bottom cutting edge 11 is 0 °. In addition, the axial direction rake angle of the straight cutting edge 13 at the connection point B between the straight cutting edge 13 and the outer circumferential cutting edge 9 is 0 °. However, the present invention is not limited to this, and the axial rake angle of the straight cutting edge 13 may be a positive value or a negative value. As shown in FIGS. 6 (c) and 7 (c), the radial direction rake angle of the straight cutting edge 13 is 0 °. However, the present invention is not limited to this, and the radial direction rake angle of the straight cutting edge 13 may be a positive value or a negative value.

As shown in FIG. 7A, of the rake face 19 of the cutting edge 4 facing the tool rotational direction R, the portion adjacent to the radial inner side and the proximal end side of the linear cutting edge 13 is a straight cutting edge 13 It is a rake face portion 14. In the example of the present embodiment, the rake face portion 14 of the straight cutting edge 13 is planar.
Further, a portion of the outer surface of the insert body 15 adjacent to the side opposite to the tool rotational direction R of the linear cutting edge 13 is a flank surface portion of the linear cutting edge 13. The flank surface portion of the linear cutting edge 13 is formed in a planar shape facing the tip side in the central axis C direction and radially outward. The flank surface portion of the straight cutting edge 13 is inclined toward the proximal end side in the central axis C direction and radially inward as it goes from the straight cutting edge 13 to the opposite side to the tool rotational direction R. A relief angle is given to the straight cutting edge 13.

  In the cutting edge portion 4, the radius of curvature of the bottom cutting edge 11 and the radius of curvature of the outer peripheral cutting edge 9 are the same as each other. In the example of the present embodiment, the radius of curvature of the bottom cutting edge 11 and the radius of curvature of the outer circumferential cutting edge 9 are the outer diameters of the rotation locus obtained by rotating the outer circumferential cutting edge 9 around the central axis C Maximum diameter, equal to blade diameter).

  In the present embodiment, the rake surface portion 12 of the bottom cutting edge 11, the raking surface portion 10 of the outer peripheral cutting edge 9 and the raking surface portion 14 of the straight cutting edge 13 of the rake face 19 are formed on the same plane. There is. That is, the entire rake face 19 of the cutting edge of the cutting edge portion 4 is formed by one plane.

Then, as shown in FIG. 7A and FIG. 8, the rake face 19 intersects the central axis C at an angle α of 45 ° when viewed from the front, and the central axis C intersects radially outward. The bottom cutting edge 11 and the outer peripheral cutting edge 9 are formed so as to be in line symmetry with each other, with the virtual straight line VL extending toward the front end side in the direction as a symmetry axis. The straight cutting edge 13 is orthogonal to the virtual straight line VL.
Specifically, in the present embodiment, when the rake face 19 is viewed from the front, the entire length of the cutting edge of the cutting edge portion 4 is formed in line symmetry with the virtual straight line VL as the axis of symmetry.

In the example of the present embodiment, the rake surface portion 12 of the bottom cutting edge 11, the raking surface portion 10 of the outer peripheral cutting edge 9, and the rake surface portion 14 of the straight cutting edge 13 are formed on the same plane. From the above, “seeing the rake face 19 in front” refers to the rake face portion 12 of the bottom cutting edge 11 in the front, and the rake face portion 10 of the outer peripheral cutting edge 9 in the front, and It is synonymous with seeing 13 rake face parts 14 in the front.
Further, the angle α indicates an acute angle among the acute angle and the obtuse angle formed by intersecting the virtual straight line VL and the central axis C.

  Further, as shown in FIG. 7A and FIG. 8, when the rake face 19 is viewed from the front, a straight line extending in the radial direction passing the tip of the bottom cutting edge 11 in the central axis C direction is a radial direction reference line A straight line extending along the direction of the central axis C through the radially outer end of the outer peripheral cutting edge 9 as a central axis direction reference line CR, the bottom cutting edge 11 at the radially outer end A of the bottom cutting edge 11 Of the outer peripheral cutting edge 9 at the tip B in the central axis C direction of the outer peripheral cutting edge 9 as a second tangent L2, and the first tangential line L1 and the radial reference line RR A right angle formed by connecting the intersection D of the first tangent L1 and the central axis direction reference line CR and the intersection F of the radial reference line RR and the central axis direction reference line CR by straight lines. Let triangle (△ DEF) be the first right triangle T1, and the second tangent L2 and the center Connect the intersection G with the direction reference line CR, the intersection H with the second tangent L2 and the radial reference line RR, and the intersection F with the radial reference line RR and the central axis direction reference line CR by straight lines. The first right triangle T1 and the second right triangle T2 are congruent with each other, with the right triangle (ΔGHF) formed being the second right triangle T2.

Further, in a front view of the rake face 19 shown in FIGS. 7A and 8, a line segment connecting the outer end A in the radial direction of the bottom cutting edge 11 and the tip B in the central axis C direction of the outer peripheral cutting edge 9. The virtual straight line passing through the middle point M of the second embodiment (the middle point M of the straight cutting edge 13 in this embodiment) and the intersection point F of the radial reference line RR and the central axis direction reference line CR coincides with the virtual straight line VL. Do.
The hole center of the screw insertion hole 18 is located on the virtual straight line VL. Specifically, in the front view of the rake face 19, the hole center of the screw insertion hole 18 is disposed on the intersection point I of the virtual straight line VL and the central axis C.

In addition, when the rake face 19 is viewed from the front, the angle θ1 formed between the first tangent L1 and the radial reference line RR is 10 to 30 °, and the second tangent L2 and the radial reference line are The angle θ2 formed between it and RR is (90 ° −θ1) °. The angle θ1 is preferably 12 to 28 °, and more preferably 12 to 25 °. However, the angles θ1 and θ2 are not limited to the numerical range in the present embodiment.
The angle θ1 refers to an acute angle or an obtuse angle formed by the intersection of the first tangent line L1 and the radial direction reference line RR. Further, the angle θ2 indicates an acute angle among the acute angle and the obtuse angle formed by the intersection of the second tangent line L2 and the radial direction reference line RR.

According to the cutting insert 5A and the indexable rotary cutting tool 6A of the present embodiment described above, the rake face 19 of the cutting edge portion 4 intersects the central axis C at an angle α of 45 ° when viewed from the front. The bottom cutting edge 11 and the outer peripheral cutting edge 9 are formed in line symmetry with the virtual straight line VL as a symmetry axis.
Alternatively, the radius of curvature of the bottom cutting edge 11 and the radius of curvature of the outer circumferential cutting edge 9 are identical to each other when the rake face 19 of the cutting edge portion 4 is viewed in front, and the radial outer end of the bottom cutting edge 11 The tangent line of the outer peripheral cutting edge 9 at the tip B in the direction of the central axis C of the first right triangle T1 (ΔDEF) whose oblique side is the tangent line (first tangent line) L1 of the bottom cutting edge 11 at A (Second tangent) The second right triangle T2 (ΔGHF) having the oblique side L2 is congruent with each other.

Therefore, for example, when performing face facing processing (flat surface processing) on a material to be cut, a grain (a processing point, a processing mark) to be imparted to the processing surface of the material to be cut by cutting with the bottom cutting edge 11; When side-cutting (standing wall surface processing) is applied to the work material, the grain produced by cutting with the outer peripheral cutting edge 9 has the same properties as the reticulations applied to the processed surface of the work material.
That is, in the present embodiment, the radius of curvature of the bottom cutting edge 11 and the radius of curvature of the outer peripheral cutting edge 9 are the same as each other, and the bottom cutting edge 11 and the outer peripheral cutting edge 9 are formed in line symmetry with each other. . Therefore, in order to equalize the cusp height of the flat portion and the cusp height of the upright wall among the machined surfaces of the work material, both can be machined with the same pick feed (pitch), You can align your eyes with each other. For this reason, it is possible to obtain a machined surface of the same quality throughout the work material.
That is, even in the case of cutting using either the bottom cutting edge 11 or the outer peripheral cutting edge 9, it is possible to make the properties of the machined surface of the work material uniform.

  Reference is now made to FIG. 11 (a) where the pitch and cusp height are shown. FIG. 11A is an enlarged view of a cross section of the machined surface of the work material W, and in the drawing, a symbol P denotes a pitch of a machining mark provided on the machined surface of the work material W (pick feed And the symbol CH represents the cusp height of the processing mark. According to the present embodiment, the pitch (width) P of the pick feed and the cusp height (depth) CH can be made uniform regardless of the processing site or shape of the work material W.

  Further, as described above, since the properties of the machined surface of the work material can be made uniform, the surface roughness, gloss, etc. of the machined surface can be made uniform over the entire machined surface. That is, the surface performance and the appearance of the entire processing surface can be made uniform. Thereby, in the finishing process and the semi-finishing process, an advantageous effect can be obtained to increase the accuracy of the process.

  In addition, the range of the inclination angle of the machined surface that can be cut by the bottom cutting edge 11 in face milling (planar machining) and the inclination angle of the machined surface that can be milled with the outer peripheral cutting edge 9 in side milling (standing wall surface machining) Since the ranges are the same as each other, it is possible to correspond to more processing shapes while uniformly aligning the properties of the processing surface of the work material.

  When the cutting insert 5A and the indexable rotary cutting tool 6A of the present embodiment are used in a machine tool such as a multi-axis control machining center, the operation and effects of the present embodiment become particularly remarkable. The multi-axis control refers to, for example, control of four to six axes. By multi-axis control, it becomes easy to process a plurality of processing surfaces with different inclinations into more uniform properties. In this case, even for a work material having a complicated three-dimensional curved surface such as a turbine blade, for example, cutting can be stably performed with high accuracy.

Specifically, when the conventional ball end mill is used in a 3-axis control cutting method, it has problems as described in the above-mentioned "Problems to be solved by the invention".
According to the cutting insert 5A and the indexable rotary cutting tool 6A of the present embodiment, it is possible to cope with a processing machine with 5-axis control, and the outer peripheral cutting edge (barrel cutting edge) 9 and the bottom cutting edge (lens cutting edge) 11 By combining and using, it became possible to realize high-efficiency processing and high-precision processing at the same time.
For example, when using the outer peripheral cutting edge (barrel cutting edge) 9 by processing with inclination of the tool axis, the processing pitch is set large on the inclined surface having the slope of the work material to achieve high efficiency processing It becomes possible to set conditions and to obtain a high quality finished surface.
Further, when the bottom cutting edge (lens cutting edge) 11 is used, as in the case of the outer peripheral cutting edge (barrel cutting edge) 9, the curved surface of the material to be cut can be a high quality finished surface.
Furthermore, even when used in a 3-axis control processing machine, by using the peripheral cutting edge (barrel cutting edge) 9, a sloped surface close to a vertical upright wall, or a bottom cutting edge (lens cutting edge) The curved surface of the work material close to a flat surface can be machined by using No. 11 under the condition that the machining pitch is set large.

  Here, with reference to FIGS. 8 to 10, the present embodiment will be described in more detail. FIG. 8 shows the cutting insert 5A of the present embodiment, and FIGS. 9 and 10 show the cutting inserts 20 and 30 of the reference example having a different technical concept from the present embodiment. 8 to 10 are plan views of the cutting inserts 5A, 20 and 30, respectively, in which the rake face 19 of the cutting edge 4 is seen from the front. All of the three cutting inserts 5A, 20, 30 shown in FIGS. 8 to 10 have the same radius of curvature as the bottom cutting edge 11 and the radius of curvature of the outer peripheral cutting edge 9.

  Then, in the cutting insert 5A of the present embodiment shown in FIG. 8, the bottom cutting edge 11 and the outer peripheral cutting edge 9 mutually make an imaginary straight line VL intersecting the central axis C at an angle α of 45 ° as a symmetry axis. It is formed to be in line symmetry. Further, in the cutting insert 5A of the present embodiment shown in FIG. 8, the first right triangle T1 (ΔDEF) and the second right triangle T2 (ΔGHF) are congruent with each other. Thereby, the above-mentioned excellent effects can be achieved.

On the other hand, in the cutting inserts 20 and 30 of the reference example shown in FIGS. 9 and 10, the radius of curvature of the bottom cutting edge 11 and the radius of curvature of the outer peripheral cutting edge 9 are identical to each other. 11 and the outer peripheral cutting edge 9 are not formed in line symmetry. Moreover, in the cutting inserts 20 and 30 of the reference example shown in FIG. 9 and FIG. 10, the first right triangle T1 (ΔDEF) and the second right triangle T2 (ΔGHF) are not congruent with each other.
Therefore, in the cutting inserts 20 and 30 of the reference example shown in FIG. 9 and FIG. 10, the face to be machined is given to the work surface by subjecting the work to face machining (planar process), and side cutting to the work material In some cases, it is difficult to make the textures applied to the processed surface by processing (standing wall surface processing) the same property as each other. That is, even if the curvature radius of the bottom cutting edge 11 and the curvature radius of the outer peripheral cutting edge 9 are set to be the same, it is not always possible to obtain the excellent operation and effect as in the above-described embodiment.

Further, according to the present embodiment, the processing time can be shortened as compared with conventional cutting tools such as ball end mills and radius end mills.
Specifically, in the conventional ball end mill type cutting tool, the rotation locus around the central axis of the cutting edge is hemispherical, and the radius of this rotation locus is the tool diameter (the maximum diameter of the rotation locus of the cutting edge , 1/2 of the blade diameter). In the ball end mill type cutting tool, the curvature radius of the cutting edge portion corresponding to the bottom cutting edge and the curvature radius of the cutting edge portion corresponding to the outer peripheral cutting edge both become 1/2 of the tool diameter. That is, in the ball end mill type cutting tool, the pick feed is set to be equal to or less than a predetermined cusp height value according to the tool radius (1/2 of the tool diameter), and cutting is performed. In the case of a radius end mill type cutting tool, a corner R cutting edge is used when cutting an inclined machined surface etc. The radius of curvature of the corner R cutting edge is generally that of the cutting edge of a ball end mill The pick feed is even smaller than the ball end mill because it is smaller than the radius of curvature (if the tool diameter is the same).

On the other hand, in the present embodiment, the radius of curvature of the bottom cutting edge 11 and the radius of curvature of the outer peripheral cutting edge 9 can be set larger than one half of the tool diameter. For this reason, in order to obtain a cusp height equivalent to the grain size of the processing surface machined by the conventional ball end mill (that is, for making the cusp height value equal to or less than a predetermined cusp height value), the pick feed (pitch) is set large according to this embodiment. can do.
In the present embodiment, the radius of curvature of the bottom cutting edge 11 and the radius of curvature of the outer peripheral cutting edge 9 are made equal to the tool diameter (the maximum diameter of the rotation trajectory of the cutting edge). Therefore, in the present embodiment, the pick feed can be set to a value approximately twice as high as that of the conventional ball end mill.

  Here, with reference to FIGS. 11A and 11B, the difference between the pick feed (pitch) of the present embodiment and that of the conventional example will be described. Fig.11 (a) represents the cross section of the processing surface (processing mark) of the cut material W cut with cutting insert 5A (blade-tip-exchange-type rotary cutting tool 6A) of this embodiment, and FIG.11 (b) The cross section of the processing surface of the cut material W cut with the conventional cutting tool is represented. In the figure, the code P is the pitch of the pick feed, and the code CH is the cusp height. As shown in FIGS. 11 (a) and 11 (b), when the cusp heights CH are set to be identical to each other, the pitch P of the pick feed can be made larger in the embodiment of FIG. 11 (a). it can.

  As described above, according to the present embodiment, it is possible to set the pick feed (pitch P) large while suppressing the cusp height CH small. Thereby, the number of asperities (scallops) provided as a processing mark on the processing surface can be reduced, and the processing surface accuracy can be enhanced. In addition, the tool path length (total processing length) can be reduced by the increase of the pick feed, and the processing time can be shortened.

  When a cutting test of the material to be cut (S50C) was actually performed using the cutting edge exchange type rotary cutting tool 6A mounted with the cutting insert 5A of this embodiment and the ball end mill of the conventional example, the tool diameter, cutting When the speed, the feed amount and the cusp height (scallop height) are set to be the same as each other, it is confirmed that the processing time can be reduced by about 30% in the present embodiment as compared with the conventional example. Further, it was found that the arithmetic average roughness Ra and the ten-point average roughness Rz of the machined surface both have values smaller than those of the conventional example in this embodiment, and the machined surface precision is excellent.

  Further, a straight cutting edge 13 connecting the bottom cutting edge 11 and the outer circumferential cutting edge 9 is provided. Therefore, it is possible to carry out planar milling (finishing) of a material to be machined, which has been difficult to be machined with high precision by a conventional ball end mill or the like, using the straight cutting edge 13. In addition, planar milling can be performed efficiently. That is, the straight cutting edge 13 has a function as a finishing blade for eliminating a grain (machined point, processing mark). For this reason, according to this embodiment, it is possible to cope with various kinds of cutting.

  As mentioned above, according to this embodiment, it is possible to perform cutting so that the property of a processing side may become equal irrespective of the processing part and shape of a work material. Therefore, in the finishing process, the semi-finishing process and the like, it is possible to obtain good machined surface accuracy over the entire machined surface.

Further, in the present embodiment, a screw insertion hole 18 which penetrates the insert main body 15 in the thickness direction is formed in the insert main body 15, and the mounting seat 3 of the tool main body 1 A fixing screw 8 for fixing the cutting insert 5A is inserted into the mating groove 7).
And, according to the present embodiment, since the hole center of the screw insertion hole 18 is located on the virtual straight line VL, even when cutting using the bottom cutting edge 11, when cutting using the outer peripheral cutting edge 9 Also in this case, the force to rotate the cutting insert 5A around the screw insertion hole 18 (fixing screw 8) is suppressed.

  Specifically, during cutting using the bottom cutting edge 11, a component in the normal direction of the cutting edge received by the bottom cutting edge 11 acts to move toward the hole center of the screw insertion hole 18. Further, at the time of cutting using the outer peripheral cutting edge 9, a cutting edge normal direction component of cutting resistance received by the outer peripheral cutting edge 9 acts so as to be directed to the hole center of the screw insertion hole 18. For this reason, the force to rotate the cutting insert 5A fixed by the fixing screw 8 around the fixing screw 8 is relaxed, and the micro-vibration (rotational micro-vibration) of the cutting insert 5A relative to the mounting seat 3 Be suppressed.

Thereby, the property of the processing surface of a work material can be stabilized and high-precision processing can be realized.
In particular, it is advantageous for high precision in finishing and semi-finishing by so-called surface milling, in which milling is performed on a component of a three-dimensional shape of a work material with a tool locus along the outer surface of the component. Effect can be obtained.
Further, at the time of cutting using the straight cutting edge 13, a component in the normal direction of the cutting edge received by the straight cutting edge 13 acts to move toward the hole center of the screw insertion hole 18. Therefore, even at the time of cutting using the straight cutting edge 13, the same operation and effect as described above can be obtained.

  Further, in the present embodiment, the outer end A in the radial direction of the bottom cutting edge 11 and the end B in the direction of the central axis C of the outer peripheral cutting edge 9 are connected via one linear cutting edge 13. For this reason, the blade length of the linear cutting edge 13 can be secured long, and the feed amount in the case of using the linear cutting edge 13 for cutting can be increased, and the processing efficiency can be enhanced.

Further, in the present embodiment, the rake surface portion 12 of the bottom cutting edge 11, the raking surface portion 10 of the outer peripheral cutting edge 9 and the rake surface portion 14 of the straight cutting edge 13 in the rake surface 19 of the cutting edge 4 are coplanar. It is formed on top. Therefore, the axial rake angle and the radial rake angle do not substantially change over the entire length of the cutting edge.
Generally, among the rake surfaces of the cutting edge portion, the rake surface portion of the bottom cutting edge and the raking surface portion of the outer peripheral cutting edge, etc. are formed by different planes or curved surfaces. And since the connection point of each cutting edge is a part to which two cutting edges which are mutually different in shape are connected, an axial direction rake angle and radial direction rake angle change. For this reason, at the time of cutting, the cutting load in the vicinity of the connection point between the cutting edges tends to be large.

Therefore, if the rake surface portion 12 of the bottom cutting edge 11, the raking surface portion 10 of the outer peripheral cutting edge 9, and the rake surface portion 14 of the straight cutting edge 13 are formed on the same plane as in this embodiment, At the connection point A between the bottom cutting edge 11 and the straight cutting edge 13 and at the connection point B between the outer peripheral cutting edge 9 and the straight cutting edge 13 as well, the rake face of the cutting edge is formed by one plane. .
As a result, a large change in axial rake angle and radial rake angle is suppressed on both sides of the cutting edge sandwiching the connection points A and B, and a large cutting load acts in the vicinity of the connection points A and B. Can be prevented. Accordingly, the strength of the cutting edge at the connection portion between the straight cutting edge 13 and the bottom cutting edge 11 and the connection portion between the straight cutting edge 13 and the outer peripheral cutting edge 9 is significantly enhanced, and the tool life is extended.

  Further, since the rake surface portion 12 of the bottom cutting edge 11, the raking surface portion 10 of the outer peripheral cutting edge 9 and the raking surface portion 14 of the straight cutting edge 13 are formed on the same plane, the manufacturing of the cutting insert 5A is easy. It is. In addition, since a recess (valley) and the like are not formed between these rake surface portions 10, 12, and 14 (connection portions), hooking of chips during cutting is suppressed, and chip discharging performance is enhanced. Be

  Further, in the present embodiment, when the rake face 19 is viewed from the front, the angle θ1 formed between the first tangent L1 and the radial direction reference line RR is 10 to 30 °, and the second tangent L2 and the diameter Since the angle θ2 formed with the direction reference line RR is (90 ° −θ1) °, the above-described effects become more remarkable. Moreover, it becomes easy to respond | correspond with the process site | part and shape of various cut materials, ensuring the cutting-blade intensity | strength of the linear cutting-edge 13 vicinity.

Specifically, since the angle θ1 is 10 ° or more (the angle θ2 is 80 ° or less), it is possible to suppress that the length of the straight cutting edge 13 becomes too long. Thereby, each blade length of the bottom cutting edge 11 and the outer peripheral cutting edge 9 is secured long, and the effect of this embodiment described above (the effect of being able to increase the pitch P of the pick feed while suppressing the cusp height CH) is further enhanced. It can be exceptional. When the angle θ1 is less than 10 ° (when the angle θ2 exceeds 80 °), the length of the linear cutting edge 13 becomes too long, so that the lengths of the bottom cutting edge 11 and the outer peripheral cutting edge 9 become short. There is a possibility that it will become difficult to acquire the above-mentioned effect. In order to make the above-mentioned effect more remarkable, it is preferable that angle theta 1 is 12 degrees or more (angle theta 2 is 78 degrees or less).
Further, since the angle θ1 is 30 ° or less (the angle θ2 is 60 ° or more), it is possible to suppress that the blade length of the straight cutting edge 13 becomes too short. Thereby, the blade length of the linear cutting edge 13 can be secured long, and the effect of the present embodiment described above (the effect that the plane milling can be efficiently performed with high accuracy by the linear cutting edge 13) can be made more remarkable. . When the angle θ1 exceeds 30 ° (when the angle θ2 is less than 60 °), the blade length of the linear cutting edge 13 becomes too short, which may make it difficult to obtain the above-described effect. Note that, in order to make the above-described effects more remarkable, the angle θ1 is preferably 28 ° or less (the angle θ2 is 62 ° or more), and is 25 ° or less (the angle θ2 is 65 ° or more). Is more desirable.

Second Embodiment
Next, a cutting insert 5B according to a second embodiment of the present invention and an indexable rotary cutting tool 6B provided with the cutting insert 5B will be described with reference to FIGS.
In the second embodiment, the same parts as the constituent elements in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted, and mainly different points will be described.

As shown in FIGS. 12 to 14, the cutting insert 5B and the indexable rotary cutting tool 6B according to the present embodiment are the same as those of the above-described embodiment except that the straight cutting edge 13 and the rake surface portion 14 included in the cutting edge portion 4 are provided. Etc. The configuration is different.
In the present embodiment, the radially outer end (connection point) A of the bottom cutting edge 11 and the tip (connection point) B in the central axis C direction of the outer circumferential cutting edge 9 are connected via a plurality of straight cutting edges 13 Do. Specifically, as shown in FIGS. 14A to 14C, the outer end A in the radial direction of the bottom cutting edge 11 and the tip B in the central axis C direction of the outer peripheral cutting edge 9 are two. It connects via the straight cutting edge 13.

As shown in FIG. 14A, the plurality of straight cutting edges 13 extend in different directions between the connection points A and B, and are formed continuously with each other.
Of the plurality of straight cutting edges 13, the straight cutting edge (first straight cutting edge) 13 connected to the bottom cutting edge 11 is proximal to the central axis C direction from the connection point A toward the outer side in the radial direction It extends obliquely to the side. Of the plurality of straight cutting edges 13, the straight cutting edge (second straight cutting edge) 13 connected to the outer circumferential cutting edge 9 extends radially inward as it extends from the connection point B toward the tip end side. There is.

The amount of displacement of the first linear cutting edge 13 in the radial direction per unit length toward the central axis C (that is, the inclination with respect to the radial direction) is the outer end A of the bottom cutting edge 11 and the outer peripheral cutting edge 9 The displacement of the line segment LS connecting the tip B in the direction of the central axis C is smaller than the displacement of the first tangent L1.
The displacement of the second straight cutting edge 13 in the direction of the central axis C per unit length in the radial direction is larger than the displacement of the line segment LS and smaller than the displacement of the second tangent line L2. .
The amount of displacement of the first linear cutting edge 13 in the direction of the central axis C per unit length in the radial direction is smaller than the displacement of the second linear cutting edge 13.

  In the present embodiment, the plurality of straight cutting edges 13 (the first straight cutting edge 13 and the second straight cutting edge 13) are disposed closer to the outer periphery of the tip of the tool than the line segment LS. When the rake face 19 is viewed from the front, the corner where the adjacent straight cutting edges 13 are connected is formed to form an obtuse angle which is convex toward the outer periphery of the tip of the tool. In addition, the virtual straight line VL passes through an intersection point F of the radial reference line RR and the central axis direction reference line CR, and the middle point M of the line segment LS.

  A connection point (the above-mentioned corner) between the first straight cutting edge 13 and the second straight cutting edge 13 is disposed on the virtual straight line VL. The connection point between the first straight cutting edge 13 and the second straight cutting edge 13 is disposed closer to the outer periphery of the tip of the tool than the midpoint M of the line segment LS. The first straight cutting edge 13 and the second straight cutting edge 13 are formed so as to be in line symmetry with each other with the imaginary straight line VL as a symmetry axis. That is, in the present embodiment, the blade length of the first straight cutting edge 13 and the blade length of the second straight cutting edge 13 are the same as each other.

  Further, among the rake surfaces 19 of the cutting edge portion 4, the raking surface portion 12 of the bottom cutting edge 11, the raking surface portion 10 of the outer peripheral cutting edge 9, and the raking surface portions 14 of the plurality of linear cutting edges 13 mutually It is formed on the same plane. In FIG.12 and FIG.13, each flank surface part of several linear cutting blade 13 is formed on a mutually different plane.

According to the cutting insert 5B of the present embodiment described above and the indexable rotary cutting tool 6B of the present embodiment, it is possible to obtain the same effect as that of the above-described embodiment.
And in this embodiment, it is possible to cope with various finishing processes and the like by the plurality of linear cutting edges 13.

  Further, in the present embodiment, since the blade length of the first straight cutting edge 13 and the blade length of the second straight cutting edge 13 are the same as each other, finishing with the first straight cutting edge 13 and The finishing process using the second straight cutting edge 13 makes it possible to make the grain (machined point, machined mark) uniform. Therefore, by cutting separately with a plurality of linear cutting edges 13, the grain boundaries provided on the machined surface of the work material have the same properties.

Third Embodiment
Next, a cutting insert 5C according to a third embodiment of the present invention and an indexable rotary cutting tool 6C provided with the same will be described with reference to FIGS.
In the third embodiment, the same parts as the constituent elements in the first and second embodiments will be assigned the same reference numerals and descriptions thereof will be omitted, and mainly different points will be described.

As shown in FIGS. 15 to 17, the cutting insert 5C and the indexable rotary cutting tool 6C according to this embodiment are the same as those of the above-described embodiment except that the straight cutting edge 13 and the rake face portion 14 provided in the cutting edge portion 4 are provided. Etc. The configuration is different.
In this embodiment, as shown in FIGS. 17A to 17C, the radial outer end (connection point) A of the bottom cutting edge 11 and the tip in the central axis C direction of the outer peripheral cutting edge 9 (connection The point) B is connected via three straight cutting edges 13.

  As shown in FIG. 17A, a plurality of straight cutting edges 13 include straight cutting edges (first straight cutting edges) 13 connected to the bottom cutting edge 11 and straight cutting edges connected to the outer peripheral cutting edge 9. Straight cutting edge (third straight cutting edge) 13 positioned between and connecting the blade (second straight cutting edge) 13 and the first straight cutting edge 13 and the second straight cutting edge 13 And is included. The third straight cutting edge 13 extends obliquely toward the base end side in the central axis C direction as it goes radially outward from the connection point with the first straight cutting edge 13.

  The amount of displacement (that is, the inclination with respect to the radial direction) in the radial direction per unit length in the third linear cutting edge 13 per unit length in the radial direction is larger than the displacement of the first linear cutting edge 13 This displacement is smaller than the displacement of the two straight cutting edges 13. In the present embodiment, the displacement of the third straight cutting edge 13 and the displacement of the line segment LS are equal to each other. That is, the third straight cutting edge 13 and the line segment LS are parallel to each other.

  In the present embodiment, the plurality of straight cutting edges 13 (first to third straight cutting edges 13) are disposed closer to the outer periphery of the tip of the tool than the line segment LS. When the rake face 19 is viewed from the front, the corner where the adjacent straight cutting edges 13 are connected is formed to form an obtuse angle which is convex toward the outer periphery of the tip of the tool.

  Connection points (corners) between the first straight cutting edge 13 and the third straight cutting edge 13 and connection points (corners) between the second straight cutting edge 13 and the third straight cutting edge 13 , And is disposed on the outer peripheral side of the tip of the tool than the line segment LS. The third straight cutting edge 13 is orthogonal to the virtual straight line VL. The first straight cutting edge 13 and the second straight cutting edge 13 are formed so as to be in line symmetry with each other with the imaginary straight line VL as a symmetry axis. In the present embodiment, the blade length of the first straight cutting edge 13, the blade length of the second straight cutting edge 13, and the blade length of the third straight cutting edge 13 are the same.

According to the cutting insert 5C and the indexable rotary cutting tool 6C of the present embodiment described above, the same function and effect as those of the above-described embodiment can be obtained.
Further, in the present embodiment, since the blade length of the first straight cutting edge 13, the blade length of the second straight cutting edge 13, and the blade length of the third straight cutting edge 13 are mutually the same, Stitches (finishing marks, machining marks) by finishing using the straight cutting edge 13 of the present invention, finishing with the second straight cutting edge 13 and finishing with the third straight cutting edge 13 Can be aligned.

  The length of the third linear cutting edge 13 may be different from the length of the first and second linear cutting edges 13. That is, the blade length of the third straight cutting edge 13 may be longer or shorter than the blade length of the first and second straight cutting edges 13. In this case, it is possible to cope with various processing forms.

Fourth Embodiment
Next, a cutting insert 5D according to a fourth embodiment of the present invention and a blade-tip-exchange-type rotary cutting tool 6D including the cutting insert 5D will be described with reference to FIGS.
In the fourth embodiment, the same parts as the constituent elements in the first to third embodiments are denoted by the same reference numerals, and the description thereof is omitted, and mainly different points will be described.

  As shown in FIGS. 18 to 20, the cutting insert 5D and the indexable rotary cutting tool 6D according to the present embodiment are different in that the cutting edge portion 4 does not have the linear cutting edge 13 and the rake surface portion 14; The configuration is different from the above embodiment.

  As shown in FIGS. 20 (a) to 20 (c), in the present embodiment, the radial outer end (connection point) A of the bottom cutting edge 11 and the tip in the central axis C direction of the outer peripheral cutting edge 9 (connection Point) B is directly connected. The radial outer end A of the bottom cutting edge 11 and the tip B in the central axis C direction of the outer peripheral cutting edge 9 are directly connected to each other. The connection point A of the bottom cutting edge 11 is an end point connected to the outer peripheral cutting edge 9 at the bottom cutting edge 11, and the connection point B of the outer peripheral cutting edge 9 is connected to the bottom cutting edge 11 at the outer peripheral cutting edge 9 It is an end point. The positions of the connection point A and the connection point B coincide with each other. The straight cutting edge 13 is not formed between the connection point A and the connection point B. For this reason, the rake face 19 of the cutting edge portion 4 does not have the rake face portion 14 of the straight cutting edge 13. The rake surface portion 12 of the bottom cutting edge 11 and the rake surface portion 10 of the outer peripheral cutting edge 9 of the rake surface 19 are formed on the same plane.

As shown in FIG. 18 to FIG. 20A, the corner portion where the radial outer end A of the bottom cutting edge 11 and the tip B in the central axis C direction of the outer peripheral cutting edge 9 are connected is the tip of the tool. It is formed to form an obtuse angle which is convex toward the outer peripheral side.
In the present embodiment, the hole centers of the screw insertion holes 18 are connection points A and B between the radially outer end A of the bottom cutting edge 11 and the tip B of the outer circumferential cutting edge 9 in the central axis C direction, and a radial direction reference. It is located on an imaginary straight line VL passing through an intersection point F of the line RR and the central axis direction reference line CR.

  Further, as shown in FIG. 20A, when the rake face 19 is viewed from the front, an angle θ1 formed between the first tangent L1 and the radial direction reference line RR is 10 to 30 °, An angle θ2 formed between the second tangent L2 and the radial reference line RR is (90 ° −θ1) °.

According to the cutting insert 5D and the indexable rotary cutting tool 6D of the present embodiment described above, the same function and effect as those of the above-described embodiment can be obtained.
And in this embodiment, since the radial outer end A of the bottom cutting edge 11 and the tip B in the central axis C direction of the outer peripheral cutting edge 9 are directly connected, the blade length and the outer circumference of the bottom cutting edge 11 It is possible to set the blade length of the cutting edge 9 to be long (longest). Therefore, it is possible to increase the pitch P of the pick feed while keeping the cusp height CH small. Therefore, the processing efficiency can be enhanced while maintaining the processing surface accuracy well. Further, since the straight cutting edge 13 and the rake face portion 14 and the flank face portion of the straight cutting edge 13 are not formed, the manufacture of the cutting insert 5D can be simplified.

Further, in the present embodiment, since the angle θ1 is 10 ° or more (the angle θ2 is 80 ° or less), connection points A and B (corners) of the bottom cutting edge 11 and the outer cutting edge 9 are on the tip outer circumference side of the tool. It is possible to suppress over-shooting toward the end. Therefore, chipping or the like of the cutting edge in the vicinity of the connection points A and B is suppressed. In order to make the above-mentioned effect more remarkable, it is preferred that angle theta 1 is 12 degrees or more (angle theta 2 is 78 degrees or less).
Further, since the angle θ1 is 30 ° or less (the angle θ2 is 60 ° or more), it is possible to suppress that the cutting edge shape of the cutting edge portion 4 as a whole becomes close to the cutting edge shape of the ball end mill. That is, the radius of curvature of each of the bottom cutting edge 11 and the outer peripheral cutting edge 9 can be set sufficiently larger than half of the diameter of the cutting edge 4 (one half of the tool diameter and the tool radius). The effect of being able to increase the pitch P of the pick feed mentioned above becomes more remarkable. In addition, in order to make the above-mentioned effect more remarkable, it is preferable that angle theta 1 is 28 degrees or less (angle theta 2 is 62 degrees or more), and is 25 degrees or less (the angle theta 2 is 65 degrees or more) Is more desirable.

  The present invention is not limited to the above-described embodiment. For example, as described below, changes in configuration and the like are possible without departing from the spirit of the present invention. Note that, in the drawings of the modified examples, the same components as those of the above-described embodiment are denoted by the same reference numerals, and mainly different points will be described.

  FIGS. 21A to 21C show modifications of the cutting insert 5A of the first embodiment. In this modification, as shown in FIG. 21 (b), the axial rake angle of the outer peripheral cutting edge 9 has a positive value. The axial rake angle of the bottom cutting edge 11 has a positive value. The axial rake angle of the straight cutting edge 13 has a positive value. The axial rake angle at the connection point A between the bottom cutting edge 11 and the straight cutting edge 13 has a positive value. The axial rake angle at the connection point B between the outer peripheral cutting edge 9 and the straight cutting edge 13 has a positive value. That is, the axial rake angle of the outer peripheral cutting edge 9, the axial rake angle of the bottom cutting edge 11, and the axial rake angle of the straight cutting edge 13 are all positive angles.

Therefore, according to this modification, chips generated at the time of cutting are efficiently sent from the tip of the tool to the base end side, and the chip discharging property is good. In addition, since the chip dischargeability is well maintained, the cutting speed can be increased, and the processing efficiency is improved.
Further, since the rake surface 19 is formed by one flat surface over the entire cutting edge length, the axial rake angle of the outer peripheral cutting edge 9, the axial rake angle of the linear cutting edge 13, and the axial direction of the bottom cutting edge 11 The rake angles are all the same angle β. For this reason, chip | tip discharge property is stably improved, and it is easy to manufacture cutting insert 5A.
In addition, you may apply the said modification to cutting inserts 5B-5D of 2nd-4th embodiment.

Further, in the above-described embodiment, the screw insertion holes 18 are formed in the cutting inserts 5A to 5D, and the hole centers of the screw insertion holes 18 are located on the virtual straight line VL. It is not a thing. That is, the hole center of the screw insertion hole 18 may not be disposed on the virtual straight line VL. However, by arranging the hole center of the screw insertion hole 18 on the virtual straight line VL, it is preferable because the excellent operation and effect described in the above embodiment can be obtained.
Alternatively, cutting inserts 5A to 5D in which screw insertion holes 18 are not formed may be used. In this case, cutting inserts 5A to 5D are detachably mounted on mounting seat 3 of tool body 1 by a clamp mechanism or the like. .

  In the second embodiment, two straight cutting edges 13 are provided in the cutting edge portion 4, and in the third embodiment, three straight cutting edges 13 are provided in the cutting edge portion 4. Instead of these configurations, four or more straight cutting edges 13 may be provided in the cutting edge portion 4. In this case, four or more rake surface portions 14 and flank surfaces of the linear cutting edge 13 are provided in the cutting edge portion 4 in accordance with the number of the linear cutting edges 13.

  In the first to third embodiments, the rake surface portion 12 of the bottom cutting edge 11, the raking surface portion 10 of the outer peripheral cutting edge 9, and the rake surface portion 14 of the straight cutting edge 13 in the rake surface 19 are coplanar. An example has been given above formed. Further, in the fourth embodiment, an example in which the rake surface portion 12 of the bottom cutting edge 11 and the rake surface portion 10 of the outer peripheral cutting edge 9 of the rake surface 19 are formed on the same plane has been described. The present invention is not limited to these configurations. For example, the rake surface portions 10, 12, and 14 may be formed on the same curved surface (convex curved surface, concave curved surface). Alternatively, the rake surface portions 10, 12, 14 may be formed by different planes or curved surfaces.

  In the above embodiment, although the angle θ1 is 10 to 30 ° and the angle θ2 is (90 ° −θ1) °, the numerical range of the angles θ1 and θ2 is not limited to the above.

In the above embodiment, the material of the base (insert main body 15) of the cutting inserts 5A to 5D is, for example, a cermet, high speed steel, in addition to cemented carbide containing tungsten carbide (WC) and cobalt (Co). , Ceramics made of titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, and mixtures thereof, cubic boron nitride sintered body, diamond sintered body, hard phase consisting of polycrystalline diamond or cubic boron nitride It is also possible to use an ultra-high pressure fired body in which a binder phase such as ceramics or iron group metal is fired under an ultra-high pressure.
Further, as the tool body 1, for example, in addition to the case of manufacturing with an alloy tool steel such as SKD 61, it is also possible to use one formed by joining an alloy tool steel such as SKD 61 and cemented carbide.

  In addition, without departing from the spirit of the present invention, each configuration (component) described in the above-described embodiment, modification, and note may be combined, and addition, omission, replacement, and other configurations can be made. Changes are possible. Moreover, this invention is not limited by embodiment mentioned above, It is limited only by the claim.

  The cutting insert and the blade-tip-exchange-type rotary cutting tool of the present invention can be subjected to cutting so that the properties of the machined surface become uniform regardless of the processing site or shape of the work material. In addition, in the finishing process, the semi-finishing process, and the like, it is possible to obtain good machined surface accuracy over the entire machined surface. Therefore, it has industrial applicability.

Reference Signs List 1 tool body 2 tip 3 mounting seat 4 cutting edge 5A to 5D cutting insert 6A to 6D cutting edge exchangeable rotary cutting tool 9 outer peripheral cutting edge 10 rake surface portion of outer peripheral cutting edge 11 bottom cutting edge 12 rake surface of bottom cutting edge Part 13 Straight cutting edge 14 Straight cutting edge rake face 15 Insert body 18 Screw insertion hole 19 Rake face A Bottom outer edge of radial cutting edge (connection point)
B Tip in the direction of the central axis of the outer peripheral cutting edge (connection point)
C central axis CR central axis direction reference line D, E, F, G, H intersection point L1 first tangent line L2 second tangent line LS segment M midpoint RR radial reference line T1 first right triangle T2 second Right triangle VL virtual straight line α angle β angle (axial direction rake angle)
θ1 angle θ2 angle

Claims (11)

A cutting insert removably mounted on a mounting seat formed at a tip of a tool body which is rotated about a central axis, the cutting insert comprising:
Plate-like insert body,
And a cutting edge formed on the insert body,
The cutting edge portion is
A bottom cutting edge disposed at the tip of the insert body in the direction of the central axis, extending along a radial direction orthogonal to the central axis, and having an arc shape that is convex toward the tip side in the direction of the central axis When,
An outer peripheral cutting edge disposed at the radially outer end of the insert body and extending along the central axis direction and having an arc shape that is convex outward in the radial direction;
Equipped with a rake face,
The radial outer end of the bottom cutting edge and the tip of the outer peripheral cutting edge in the central axial direction are directly connected via a straight cutting edge, or
Looking at the rake face in front,
The bottom cutting edge and the outer peripheral cutting edge intersect an imaginary straight line intersecting at an angle of 45 ° with the central axis and extending toward the distal end side of the central axial direction toward the outer side in the radial direction The cutting inserts are formed to be in line symmetry with each other. A cutting insert according to claim 1, wherein
The insert body is formed with a screw insertion hole penetrating the insert body in the thickness direction,
The cutting insert in which the hole center of the screw insertion hole is located on the virtual straight line. A cutting insert removably mounted on a mounting seat formed at a tip of a tool body which is rotated about a central axis, the cutting insert comprising:
Plate-like insert body,
And a cutting edge formed on the insert body,
The cutting edge portion is
A bottom cutting edge disposed at the tip of the insert body in the direction of the central axis, extending along a radial direction orthogonal to the central axis, and having an arc shape that is convex toward the tip side in the direction of the central axis When,
An outer peripheral cutting edge disposed at the radially outer end of the insert body and extending along the central axis direction and having an arc shape that is convex outward in the radial direction;
Equipped with a rake face,
The radius of curvature of the bottom cutting edge and the radius of curvature of the peripheral cutting edge are identical to each other,
The radial outer end of the bottom cutting edge and the tip of the outer peripheral cutting edge in the central axial direction are directly connected via a straight cutting edge, or
Looking at the rake face in front,
A straight line extending along the radial direction passing through the tip in the central axis direction of the bottom cutting edge is a radial reference line,
A straight line extending along the central axis direction through the radially outer end of the outer peripheral cutting edge is taken as a central axial direction reference line,
The tangent of the bottom cutting edge at the radial outer end of the bottom cutting edge is a first tangent,
The tangent of the outer peripheral cutting edge at the tip of the outer peripheral cutting edge in the central axis direction is taken as a second tangent,
An intersection point of the first tangent line and the radial direction reference line, an intersection point of the first tangent line and the central axis direction reference line, and an intersection point of the radial direction reference line and the central axis direction reference line, A right triangle formed by connecting straight lines to each other as a first right triangle,
An intersection point of the second tangent line and the central axis direction reference line, an intersection point of the second tangent line and the radial direction reference line, and an intersection point of the radial direction reference line and the central axis direction reference line A right triangle formed by connecting straight lines to each other as a second right triangle,
A cutting insert, wherein the first right triangle and the second right triangle are congruent with each other. A cutting insert according to claim 3, wherein
The insert body is formed with a screw insertion hole penetrating the insert body in the thickness direction,
Connection between the center of the line connecting the outer end of the bottom cutting edge in the radial direction to the tip of the outer peripheral cutting edge in the axial direction or the connection of the outer end to the tip A cutting insert located on an imaginary straight line passing a point and an intersection point of the radial reference line and the central axial direction reference line. It is a cutting insert according to any one of claims 1 to 4,
A cutting insert, wherein the radially outer end of the bottom cutting edge and the tip of the outer circumferential cutting edge in the central axial direction are connected via one of the straight cutting edges. It is a cutting insert according to any one of claims 1 to 4,
A cutting insert, wherein the radial outer end of the bottom cutting edge and the tip of the outer peripheral cutting edge in the central axial direction are connected via a plurality of straight cutting edges. The cutting insert according to any one of claims 1 to 6, wherein
The radially outer end of the bottom cutting edge and the tip of the outer circumferential cutting edge in the central axial direction are connected via the straight cutting edge,
The cutting insert, wherein among the rake surfaces, the rake surface portion of the bottom cutting edge, the raking surface portion of the outer peripheral cutting edge, and the raking surface portion of the straight cutting edge are formed on the same plane. It is a cutting insert according to any one of claims 1 to 4,
The radial outer end of the bottom cutting edge and the tip of the outer peripheral cutting edge in the central axial direction are directly connected,
A cutting insert, wherein among the rake surfaces, the rake surface portion of the bottom cutting edge and the raking surface portion of the outer peripheral cutting edge are formed on the same plane. The cutting insert according to any one of claims 1 to 8, wherein
Looking at the rake face in front,
A straight line extending along the radial direction passing through the tip in the central axis direction of the bottom cutting edge is a radial reference line,
The tangent of the bottom cutting edge at the radial outer end of the bottom cutting edge is a first tangent,
The tangent of the outer peripheral cutting edge at the tip of the outer peripheral cutting edge in the central axis direction is taken as a second tangent.
An angle θ1 formed between the first tangent and the radial reference line is 10 to 30 °,
A cutting insert, wherein the angle θ2 formed between the second tangent and the radial reference line is (90 ° -θ1) °. A cutting insert according to any one of the preceding claims, wherein
The axial rake angle of the peripheral cutting edge has a positive value,
A cutting insert, wherein the axial rake angle of the bottom cutting edge has a positive value. A tool body which is rotated about a central axis,
A mounting seat formed at the tip of the tool body;
And a cutting insert detachably mounted on the mounting seat.
An indexable rotary cutting tool using the cutting insert according to any one of claims 1 to 10 as the cutting insert.

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