JP7006179B2 - Cutting inserts and cutting tool with replaceable cutting edge - Google Patents

Description

The present invention relates to a cutting insert suitable for performing face cutting (flat surface processing), side surface cutting (standing wall surface processing), etc. on a work material, and a cutting tool with a replaceable cutting edge to which the cutting insert is attached.

Conventionally, for example, solid type end mills as shown in the following Patent Documents 1 and 2 are known. This type of end mill includes a shank that is rotated around 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 arranged at the tip end portion in the central axis direction, and a bottom cutting edge having an arc shape that is convex toward the tip end side is arranged at the outer end portion in the radial direction toward the outside in the radial direction. An outer peripheral cutting edge forming an arc shape that is convex toward the outside is arranged.
Then, the bottom cutting edge is used when the front surface cutting process (flat surface processing) is performed on the work material, and the outer peripheral cutting edge is used when the side surface cutting process (standing wall surface processing) is performed. ..

Special Table 2010-5200064 Japanese Unexamined Patent Publication No. 2007-152502

However, the above-mentioned conventional end mill has the following problems.
When the front surface cutting process is applied to the work material, the grain (processed grain, processing mark) given to the machined surface by cutting with the bottom cutting edge, and the outer circumference cut when the side surface cutting process is performed. It was difficult to finish the grinds given to the machined surface by cutting with a blade to have the same properties as each other. That is, the properties of the machined surface after cutting vary depending on the machined portion and shape of the work material, and it is not possible to equalize the machining accuracy of the machined surface as a whole in finishing and semi-finishing.

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 are uniform regardless of the machined portion and shape of the work material. , And it is an object of the present invention to provide a rotary cutting tool with a replaceable cutting edge using the same.

One aspect of the present invention is a cutting insert that is detachably mounted on a mounting seat formed at the tip of a tool body that is rotated around a central axis, and is attached to a plate-shaped insert body and the insert body. The cutting edge portion is provided with a formed cutting edge portion, and the cutting edge portion is arranged at the tip end portion in the central axis direction of the insert body, extends along a radial direction orthogonal to the central axis, and has the central axis. A bottom cutting edge having an arc shape that is convex toward the tip side in the direction, and a bottom cutting edge that is arranged at the radial outer end of the insert body, extends along the central axis direction, and is outward in the radial direction. It is provided with an outer peripheral cutting edge forming an arc shape that is convex toward, a rake surface, and 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. Connected via a cutting edge, the rake face is viewed from the front, intersects the central axis at an angle of 45 °, and as it goes outward in the radial direction toward the tip side in the central axis direction. The bottom cutting edge and the outer peripheral cutting edge are formed so as to have a line-symmetrical shape with each other with the extending virtual straight line as the axis of symmetry.
Further, one aspect of the present invention is a cutting insert that is detachably mounted on a mounting seat formed at the tip of a tool body that is rotated around a central axis, and is a plate-shaped insert body and the insert. A cutting edge portion formed on the main body is provided, and the cutting edge portion is arranged at the tip end portion of the insert main body in the central axis direction, extends along a radial direction orthogonal to the central axis, and is described as described above. A bottom cutting edge having an arc shape that is convex toward the tip side in the central axis direction, and a bottom cutting edge that is arranged at the outer end portion of the insert body in the radial direction, extends along the central axis direction, and has the radial direction. It is provided with an outer peripheral cutting edge having an arc shape that is convex toward the outside, and a rake face, and the radius of curvature of the bottom cutting edge and the radius of curvature of the outer peripheral cutting edge are the same as each other, and the bottom The radial outer end of the cutting edge and the central axial tip of the outer peripheral cutting edge are connected via a straight cutting edge, and the rake face is viewed in front of the cutting edge. A straight line extending along the radial direction through the tip in the central axial direction is used as a radial reference line, and a straight line extending along the central axial direction through the outer end in the radial direction of the outer peripheral cutting edge is used as a central axial reference line. The tangent line of the bottom cutting edge at the radial outer end of the bottom cutting edge is the first tangent line, and the tangent line of the outer peripheral cutting edge at the tip of the outer peripheral cutting edge in the central axis direction is the second tangent line. The intersection of the first tangent line and the radial reference line, the intersection of the first tangent line and the central axial reference line, and the intersection of the radial reference line and the central axial reference line. The right-angled triangle formed by connecting each other with a straight line is defined as the first right-angled triangle, the intersection of the second tangent line and the central axial reference line, and the intersection of the second tangent line and the radial reference line. And, the right-angled triangle formed by connecting the intersections of the radial reference line and the central axial reference line with each other by a straight line is defined as the second right-angled triangle, and the first right-angled triangle and the second right-angled line are formed. It is characterized in that the triangles are congruent with each other.
Further, one aspect of the present invention includes a tool body that is rotated around a central axis, a mounting seat formed at the tip of the tool body, and a cutting insert that is detachably mounted on the mounting seat. It is a rotary cutting tool with a replaceable cutting edge, and is characterized in that the above-mentioned cutting insert is used as the cutting insert.

Further, in the cutting insert, the insert body is formed with a screw insertion hole penetrating the insert body in the thickness direction, and the hole center of the screw insertion hole is located on the virtual straight line. Is preferable.
Further, in the cutting insert, the insert body is formed with a screw insertion hole penetrating the insert body in the thickness direction, and the hole center of the screw insertion hole is in the radial direction of the bottom cutting edge. Located on a virtual straight line passing through the midpoint of the line segment connecting the outer end and the tip of the outer peripheral cutting edge in the central axial direction, and the intersection of the radial reference line and the central axial reference line. It is preferable to have.

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

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

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

Further, in the cutting insert, when the rake face is viewed from the front, a straight line extending along the radial direction through the tip in the central axis direction of the bottom cutting edge is set as a radial reference line, and the bottom cutting edge is said to be the same. The tangent of the bottom cutting edge at the outer end in the radial direction is the first tangent, and the tangent of the outer peripheral cutting edge at the tip of the outer peripheral cutting edge in the central axis direction is the second tangent. The angle θ1 formed between the radial reference line is 10 to 30 °, and the angle θ2 formed between the second tangent line and the radial reference line is (90 ° −θ1). ) ° is preferred.

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

According to the cutting insert and the rotary cutting tool with a replaceable cutting edge of the present invention, it is possible to perform cutting so that the properties of the machined surface are uniform regardless of the machined portion and 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 cutting edge exchange type rotary cutting tool of 1st Embodiment of this invention. It is a top view of the rotary cutting tool with exchangeable cutting edge. It is a side view of the cutting edge exchange type rotary cutting tool. It is a front view of a rotary cutting tool with a replaceable cutting edge. It is a perspective view which shows the cutting insert of 1st Embodiment. It is (a) plan view, (b) side view, (c) front view which shows the cutting insert. It is (a) plan view, (b) side view, (c) front view which the cutting edge portion of a cutting insert is enlarged and shown. It is a top view of the cutting insert of 1st Embodiment which looked at the rake face from the front. It is a top view of the cutting insert of the reference example which looked at the rake face from the front. It is a top view of the cutting insert of the reference example which looked at the rake face from the front. (A) A diagram showing the pick feed pitch and cusp height of the machined surface cut by the cutting insert (rotary cutting tool with replaceable cutting edge) of the present invention, (b) the pick feed pitch and cusp height of the machined surface cut by the conventional cutting tool. It is a figure which shows the cusp height. It is a perspective view which shows the cutting edge exchange type rotary cutting tool of the 2nd Embodiment of this invention. It is a perspective view which shows the cutting insert of 2nd Embodiment. It is (a) plan view, (b) side view, (c) front view which the cutting edge portion of a cutting insert is enlarged and shown. It is a perspective view which shows the cutting edge exchange type rotary cutting tool of the 3rd Embodiment of this invention. It is a perspective view which shows the cutting insert of the 3rd Embodiment. It is (a) plan view, (b) side view, (c) front view which the cutting edge portion of a cutting insert is enlarged and shown. It is a perspective view which shows the cutting edge exchange type rotary cutting tool of the reference example of this invention. It is a perspective view which shows the cutting insert of a reference example . It is (a) plan view, (b) side view, (c) front view which the cutting edge portion of a cutting insert is enlarged and shown. It is (a) plan view, (b) side view, (c) front view which shows the modification of the cutting insert of embodiment of this invention.

<First Embodiment>
Hereinafter, the cutting insert 5A according to the first embodiment of the present invention and the cutting edge exchangeable rotary cutting tool 6A provided with the cutting insert 5A will be described with reference to FIGS. 1 to 11. In addition, in the drawing used for the description of the embodiment, in order to make it easy to understand the features of the present invention, the main part may be enlarged, emphasized, or excerpted.

The cutting insert 5A of the present embodiment connects a convex arcuate bottom cutting edge 11 called a so-called lens, a convex arcuate outer peripheral cutting edge 9 called a barrel, and a bottom cutting edge 11 and an outer peripheral cutting edge 9. A straight cutting edge 13 having a linear shape and a compound cutting edge composed of the cutting edge 13 are provided. The cutting edge exchangeable rotary cutting tool 6A provided with the cutting insert 5A is used to perform various cutting processes including front surface cutting (flat surface processing) and side surface cutting (standing wall surface processing) on the work material. It is suitable, and in particular, excellent surface accuracy can be obtained in finishing and intermediate finishing of a machined surface.

As shown in FIGS. 1 to 4, the blade tip exchange type rotary cutting tool 6A has a substantially cylindrical tool body 1 rotated around the central axis C and a tip portion 2 of the tool body 1 in the central axis C direction. It includes a formed mounting seat 3 and a cutting insert 5A that is detachably mounted on the mounting seat 3 and has a cutting edge portion 4.

The cutting edge replaceable rotary cutting tool 6A of the present embodiment includes a tool body 1 made of a steel material or the like, and a cutting insert 5A made of a cemented carbide or the like harder than the tool body 1. A plate-shaped cutting insert 5A is removable from the mounting seat (insert mounting seat) 3 formed on the tip portion 2 of the tool body 1 with the insert central axis aligned with the tool central axis C. It will be installed. The cutting insert 5A attached to the mounting seat 3 is arranged so that the cutting edge portion 4 thereof projects toward the tip end side of the tool body 1 and outward in the radial direction.

In the rotary cutting tool 6A with replaceable cutting edge, the base end portion (shank portion) of the tool body 1 is attached to the spindle (not shown) of the machine tool, and the spindle is rotationally driven so as to be around the central axis C. It is rotated in the tool rotation direction R. Then, the tool body 1 is sent together with the spindle in the direction intersecting the central axis C and in the direction of the central axis C, so that the cutting edge portion 4 of the cutting insert 5A cuts into the work material made of a metal material or the like. , Perform milling process (milling process). The blade tip exchange type rotary cutting tool 6A of the present embodiment is more preferably used for a machine tool such as a machining center with multi-axis control of 4 to 6 axes, for example.

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. Further, of the central axis C directions, the direction from the shank portion of the tool body 1 toward the mounting seat 3 (lower side in FIGS. 2 and 3) is referred to as the tip side, and the direction from the mounting seat 3 toward the shank portion (FIGS. 2 and 3). The upper side in FIG. 3) is referred to as the base end side.

Further, the direction orthogonal to the central axis C is called the radial direction. Of the radial directions, the direction approaching the central axis C is referred to as the inner side in the radial direction, and the direction away from the central axis C is referred to as the outer side in the radial direction.
Further, the direction of orbiting around the central axis C is called the circumferential direction. Of the circumferential directions, 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 rotation direction opposite to this is the side opposite to the tool rotation direction R (that is, the anti-tool rotation direction). ).

The above definition of the direction is also applied to the cutting insert 5A in which the insert central axis is aligned (arranged coaxially) with the central axis C of the cutting tool exchangeable rotary cutting tool 6A. To. Therefore, in FIGS. 6 to 10 and the like showing the cutting insert 5A, the insert central axis is represented by using the same reference numeral C as the central axis C.

1 to 4, the mounting seat 3 has a slit-shaped insert fitting groove 7 formed in the tip end portion 2 of the tool body 1 including the central axis C of the tool and extending in the radial direction, and insert fitting. It includes a fixing screw 8 for fixing the cutting insert 5A inserted in the groove 7.

The insert fitting groove 7 opens on the tip surface of the tool body 1, extends in the radial direction of the tool body 1, and also opens on the outer peripheral surface of the tool body 1. The insert fitting groove 7 has a slit shape formed to a predetermined length (depth) from the tip surface of the tool body 1 toward the proximal end side.

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

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

As shown in FIGS. 5 to 8, the cutting insert 5A is formed on the plate-shaped insert main body 15, the cutting edge portion 4 formed on the insert main body 15, and the insert main body 15, and the insert main body 15 is thickened. It is provided with a screw insertion hole 18 penetrating in the radial direction.
The cutting insert 5A of the present embodiment is formed to be front-back inverted symmetry (180 ° rotational symmetry) with the central axis C as the axis of symmetry.

The insert body 15 has a substantially flat plate shape. The front and back surfaces of the insert body 15 facing the thickness direction are a pair of flat surface portions 16 and 17. The screw insertion hole 18 is a through hole formed by penetrating the insert main body 15 in the thickness direction and opening into one flat surface portion 16 and the other flat surface portion 17. A fixing screw 8 is inserted into the screw insertion hole 18 when the cutting insert 5A is attached to and fixed to the mounting seat 3. The arrangement of the screw insertion holes 18 in the insert body 15 will be described later separately.

The cutting edge portion 4 is arranged at the tip end portion in the central axis C direction and the outer end portion in the radial direction in the insert main body 15. The cutting edge portion 4 has a rake face 19 facing the tool rotation direction R, a flank intersecting the rake face 19 and facing at least one of the tip side and the radial outer side, and an intersecting ridge line between the rake face 19 and the flank. It is equipped with a cutting edge formed in.
The cutting edge includes an outer peripheral cutting edge 9, a bottom cutting edge 11, and a straight cutting edge 13. The cutting edge is provided with an outer peripheral cutting edge 9, a bottom cutting edge 11, and a straight cutting edge 13, so that the cutting edge has a substantially L shape as a whole. Further, for each cutting edge (9, 11, 13), a rake face portion (10, 12, 14) described later of the rake face 19 and a flank portion of the flank surface are arranged adjacent to each other.

The cutting insert 5A of the present embodiment is a two-flute cutting insert, and is a set of the cutting edges provided with an outer peripheral cutting edge 9, a bottom cutting edge 11 and a straight cutting edge 13, with 180 centering on the central axis C. ° It has two sets in rotational symmetry.

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

Of the total length of the cutting edge of the cutting edge portion 4, the radial inner end of the bottom cutting edge 11 is located at the most advanced end in the central axis C direction. In the present embodiment, the radial inner end of the bottom cutting edge 11 is arranged on the central axis C. The tangent (diametrical reference line) RR at the radial inner end of the bottom cutting edge 11 (the most advanced end in the central axis C direction) extends parallel to the plane (horizontal plane) perpendicular to the central axis C.

When the cutting insert 5A is mounted on the mounting seat 3 (insert fitting groove 7) of the tool body 1 and the cutting tool 6A with replaceable cutting edge is rotated around the central axis C, the rotation locus of the bottom cutting edge 11 becomes the tip. It has a convex lens shape that bulges toward 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 present 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). Further, as shown in FIGS. 6 (c) and 7 (c), the radial rake angle of the bottom cutting edge 11 is set to 0 °.

As shown in FIG. 7A, of the rake face 19 of the cutting edge portion 4 facing the tool rotation direction R, the portion adjacent to the base end side of the bottom cutting edge 11 in the central axis C direction is the bottom cutting edge. The rake face portion 12 of 11. In the example of this embodiment, the rake face portion 12 of the bottom cutting edge 11 has a flat shape.
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 portion of the bottom cutting edge 11. The flank portion of the bottom cutting edge 11 has a curved surface shape that is convex toward the tip end side. The flank 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 side opposite to the tool rotation direction R, whereby the bottom cutting edge 11 becomes formed. Is given a clearance angle.

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

Of the total length of the cutting edge of the cutting edge portion 4, the base end of the outer peripheral cutting edge 9 in the central axis C direction is located at the outermost end in the radial direction. The tangent line (center axis direction reference line, which will be described later) CR at the base end (outermost end in the radial direction) of the outer peripheral cutting edge 9 in the central axis C direction is parallel to the plane (vertical surface) parallel to the central axis C. Extend.

When the cutting insert 5A is mounted on the mounting seat 3 of the tool body 1 and the cutting edge exchangeable rotary cutting tool 6A is rotated around the central axis C, the rotation locus of the outer peripheral cutting edge 9 bulges outward in the radial direction. It has a barrel shape (barrel shape).

In the example of this embodiment, as shown in FIG. 7B, the axial rake angle (corresponding to the helix 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. Further, the radial rake angle (center direction rake angle; radial rake) of the outer peripheral cutting edge 9 is set to 0 °. However, the present invention is not limited to this, and the radial 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 portion 4 facing the tool rotation direction R, the portion adjacent to the radial inner side of the outer peripheral cutting edge 9 is the rake face portion of the outer peripheral cutting edge 9. It is 10. In the example of this embodiment, the rake face 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 outward in the radial direction, the portion adjacent to the side opposite to the tool rotation direction R of the outer peripheral cutting edge 9 is the flank portion of the outer peripheral cutting edge 9. The flank portion of the outer peripheral cutting edge 9 has a curved surface shape that is convex toward the outside in the radial direction. The flank portion of the outer peripheral cutting edge 9 is inclined inward in the radial direction from the outer peripheral cutting edge 9 toward the side opposite to the tool rotation direction R, whereby the outer peripheral cutting edge 9 is provided with a clearance angle. Has been done.

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

The straight cutting edge 13 is inclined toward the base end side in the central axis C direction from the radial inner end (connection point A) of the straight cutting edge 13 connected to the bottom cutting edge 11 toward the outside in the radial direction. And is extending. The straight cutting edge 13 extends inwardly in the radial direction from the base end (connection point B) in the central axis C direction of the straight cutting edge 13 connected to the outer peripheral cutting edge 9 toward the tip end side. ..

When the cutting insert 5A is mounted on the mounting seat 3 of the tool body 1 and the cutting edge exchangeable rotary cutting tool 6A is rotated around the central axis C, the rotation locus of the straight cutting edge 13 moves toward the tip side in the central axis C direction. It is formed into a tapered tubular shape that gradually shrinks in diameter as it goes toward it.

In the example of this embodiment, as shown in FIG. 7B, the axial rake angle of the straight cutting edge 13 is 0 °. Therefore, the axial 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 °. Further, the axial rake angle of the straight cutting edge 13 at the connection point B between the straight cutting edge 13 and the outer peripheral 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 rake angle of the straight cutting edge 13 is set to 0 °. However, the present invention is not limited to this, and the radial 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 portion 4 facing the tool rotation direction R, the portion of the straight cutting edge 13 that is radially inside and adjacent to the base end side is the straight cutting edge 13. It is a rake face portion 14. In the example of this embodiment, the rake face portion 14 of the straight cutting edge 13 has a planar shape.
Further, on the outer surface of the insert main body 15, a portion adjacent to the side opposite to the tool rotation direction R of the straight cutting edge 13 is a flank portion of the straight cutting edge 13. The flank portion of the straight cutting edge 13 is formed in a planar shape facing the tip side in the central axis C direction and the radial side. The flank portion of the straight cutting edge 13 is inclined from the straight cutting edge 13 toward the proximal end side in the central axis C direction and inward in the radial direction as it goes toward the side opposite to the tool rotation direction R. A clearance angle is provided 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 peripheral cutting edge 9 are the outer diameter of the rotation locus obtained by rotating the outer peripheral cutting edge 9 around the central axis C (cutting edge portion 4). It is the maximum diameter and is equal to the blade diameter).

Further, in the present embodiment, of the rake face 19, the rake face portion 12 of the bottom cutting edge 11, the rake face portion 10 of the outer peripheral cutting edge 9, and the rake face portion 14 of the straight cutting edge 13 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 flat surface.

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

In the example of the present embodiment, the rake face portion 12 of the bottom cutting edge 11, the rake face portion 10 of the outer peripheral cutting edge 9, and the rake face portion 14 of the straight cutting edge 13 are formed on the same plane with each other. Therefore, in the above "viewing the rake face 19 from the front", the rake face portion 12 of the bottom cutting edge 11 is viewed from the front, the rake surface portion 10 of the outer peripheral cutting edge 9 is viewed from the front, and the straight cutting edge. It is synonymous with looking at the rake face portion 14 of 13 from the front.
Further, the angle α refers to an acute angle among the acute and obtuse angles formed by the intersection of the virtual straight line VL and the central axis C.

Further, as shown in FIGS. 7A and 8, when the rake face 19 is viewed from the front, a straight line extending along the radial direction through the tip of the bottom cutting edge 11 in the central axis C direction is a radial reference line. RR, a straight line extending along the central axis C direction through the radial outer end of the outer peripheral cutting edge 9 is defined as the central axial reference line CR, and the bottom cutting edge 11 at the radial outer end A of the bottom cutting edge 11. The tangent line of the outer peripheral cutting edge 9 is the first tangent line L1, the tangent line of the outer peripheral cutting edge 9 at the tip B in the central axis C direction of the outer peripheral cutting edge 9 is the second tangent line L2, and the first tangent line L1 and the radial reference line RR. D, the intersection E of the first tangent line L1 and the central axial reference line CR, and the intersection F of the radial reference line RR and the central axial reference line CR are connected by a straight line to each other at a right angle. Let the triangle (ΔDEF) be the first right-angled triangle T1, the intersection G between the second tangent line L2 and the central axial reference line CR, the intersection H between the second tangent line L2 and the radial reference line RR, and the diameter. A right angle triangle (ΔGHF) formed by connecting the intersection F of the direction reference line RR and the central axis direction reference line CR with a straight line is used as the second right angle triangle T2, and the first right angle triangle T1 and the second right line triangle T1. The right angle triangle T2 is congruent with each other.

Further, in the front view of the rake face 19 shown in FIGS. 7A and 8, a line segment connecting the outer end A of the bottom cutting edge 11 in the radial direction and the tip B of the outer peripheral cutting edge 9 in the central axis C direction. The virtual straight line passing through the midpoint M (the midpoint M of the straight line cutting edge 13 in the present embodiment) and the intersection F between the radial reference line RR and the central axial reference line CR coincides with the above virtual straight line VL. do.
The 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 arranged on the intersection I of the virtual straight line VL and the central axis C.

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

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

Therefore, for example, when face-cutting (flat surface machining) is performed on the work material, the grinds (work marks, machine marks) given to the machined surface of the work material by cutting with the bottom cutting edge 11 and When the side surface cutting process (standing wall surface processing) is performed on the work material, the grain provided on the machined surface of the work material by cutting with the outer peripheral cutting edge 9 has the same properties as each other.
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 line-symmetrically with each other. .. Therefore, in order to equalize the cusp height of the flat surface portion and the cusp height of the standing wall portion of the machined surface of the work material, both can be processed with the same pick feed (pitch), and the flat surface portion and the standing wall portion can be ground. You can align your eyes with each other. Therefore, it is possible to obtain a machined surface having the same quality over the entire work material.
That is, in the case of cutting using either the bottom cutting edge 11 or the outer peripheral cutting edge 9, the properties of the machined surface of the work material can be made uniform.

Now refer to FIG. 11 (a) where the pitch and cusp height are shown. FIG. 11A is an enlarged view showing a cross section of the machined surface of the work material W, in which the reference numeral P is the pitch (pick feed) of the machined marks given to the machined surface of the work material W. (Corresponding to the pitch of), and the reference numeral CH represents the cusp height of the machined mark. According to this embodiment, the pitch (width) P and the cusp height (depth) CH of the pick feed can be made constant regardless of the processing portion and 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 and gloss of the machined surface can be made uniform over the entire machined surface. That is, the surface performance and appearance of the entire machined surface can be made uniform. As a result, in the finishing process and the intermediate finishing process, it is possible to obtain an advantageous effect for improving the processing accuracy.

Further, the range of the inclination angle of the machined surface that can be cut by the bottom cutting edge 11 in the front cutting process (flat surface processing) and the inclination angle of the machined surface that can be cut by the outer peripheral cutting edge 9 in the side surface cutting process (standing wall surface processing). Since the ranges are the same as each other, it is possible to cope with a larger number of machined shapes while keeping the properties of the machined surface of the work material constant.

When the cutting insert 5A and the cutting edge exchange type rotary cutting tool 6A of the present embodiment are used for a machine tool such as a multi-axis control machining center, the action and effect of the present embodiment become more remarkable. The multi-axis control refers to control of, for example, 4 to 6 axes. The multi-axis control makes it easier to process a plurality of machined surfaces having different inclinations into more uniform properties. In this case, even a work material having a complicated three-dimensional curved surface such as a turbine blade can be stably cut with high accuracy.

Specifically, when the conventional ball end mill is used in the cutting method of 3-axis control, it has a problem as described in the above-mentioned "Problem to be solved by the invention".
According to the cutting insert 5A and the cutting edge exchangeable rotary cutting tool 6A of the present embodiment, it is possible to correspond to a processing machine by 5-axis control, and the outer peripheral cutting edge (barrel cutting edge) 9 and the bottom cutting edge (lens cutting edge) 11 By using these in combination, it has become possible to realize high-efficiency machining and high-precision machining at the same time.
For example, when the outer peripheral cutting edge (barrel cutting edge) 9 is used by inclining the tool axis, the machining pitch is set large on the inclined surface having the gradient of the work material to perform highly efficient machining. It is possible to set conditions and obtain a high-quality finished surface.
Further, when the bottom cutting edge (lens cutting edge) 11 is also used, the curved surface of the work material can be made into a high-quality finished surface as in the case of the outer peripheral cutting edge (barrel cutting edge) 9.
Furthermore, even when used in a 3-axis control processing machine, by using the outer peripheral cutting edge (barrel cutting edge) 9, a gradient surface close to a vertical vertical wall or a bottom cutting edge (lens cutting edge) can be used. By using No. 11, the curved surface of the work material, which is close to a flat surface, can be machined under the condition that the machining pitch is set large.

Here, the present embodiment will be described in more detail with reference to FIGS. 8 to 10. 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 whose technical concept is different from that of 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 portion 4 is viewed from the front. The three cutting inserts 5A, 20 and 30 shown in FIGS. 8 to 10 all have the same radius of curvature of 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 have each other with the virtual straight line VL intersecting the central axis C at an angle α of 45 ° as the axis of symmetry. It is formed so as to have a line-symmetrical shape. 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. As a result, the above-mentioned excellent action and effect are obtained.

On the other hand, in the cutting inserts 20 and 30 of the reference examples 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 the same as each other, but the bottom cutting edge is related to the virtual straight line VL. 11 and the outer peripheral cutting edge 9 are not formed in a line-symmetrical shape. Further, in the cutting inserts 20 and 30 of the reference examples shown in FIGS. 9 and 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 examples shown in FIGS. 9 and 10, the work material is subjected to frontal cutting (flat surface processing) to give a grind to the machined surface, and the work material is side-cut. It may be difficult to make the grain given to the machined surface by processing (standing wall processing) the same as each other. That is, even if the radius of curvature of the bottom cutting edge 11 and the radius of curvature of the outer peripheral cutting edge 9 are simply set to be the same, it is not always possible to obtain the excellent effects as in the present embodiment described above.

Further, according to the present embodiment, the machining time can be shortened as compared with a conventional cutting tool such as a ball end mill or a radius end mill.
Specifically, in a 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). , Blade diameter). In the ball end mill type cutting tool, the radius of curvature of the cutting edge portion corresponding to the bottom cutting edge and the radius of curvature of the cutting edge portion corresponding to the outer peripheral cutting edge are both 1/2 of the tool diameter. That is, in the ball end mill type cutting tool, the pick feed is set so as to be equal to or less than a predetermined cusp height value according to the tool radius (1/2 of the tool diameter), and the cutting process is performed. Further, in the case of a radius end mill type cutting tool, a corner R cutting edge is used when cutting an inclined machined surface or the like, and the radius of curvature of the corner R cutting edge is generally the cutting edge of a ball end mill. Since it is smaller than the radius of curvature (when the tool diameters are the same), the pick feed is even smaller than the ball end mill.

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 1/2 of the tool diameter. Therefore, in order to obtain a cusp height equivalent to the cusp height of the grain of the machined surface processed by the conventional ball end mill (that is, when the cusp height is set to a predetermined cusp height value or less), the pick feed (pitch) is set large according to the present embodiment. can do.
In this embodiment, the radius of curvature of the bottom cutting edge 11 and the radius of curvature of the outer peripheral cutting edge 9 are equal to the tool diameter (the maximum diameter of the rotation locus of the cutting edge). Therefore, in the present embodiment, the pick feed can be set to a value close to twice that of the conventional ball end mill.

Here, the difference between the present embodiment and the conventional pick feed (pitch) will be described with reference to FIGS. 11 (a) and 11 (b). FIG. 11 (a) shows a cross section of a machined surface (machined mark) of the work material W cut by the cutting insert 5A (cutting edge replaceable rotary cutting tool 6A) of the present embodiment, and FIG. 11 (b) shows. , Represents the cross section of the machined surface of the work material W cut with a conventional cutting tool. In the figure, the reference numeral P is the pitch of the pick feed, and the reference numeral CH is the cusp height. As shown in FIGS. 11 (a) and 11 (b), when the cusp height CHs are set to be the same as each other, the present embodiment of FIG. 11 (a) may increase the pitch P of the pick feed. can.

As described above, according to the present embodiment, the pick feed (pitch P) can be set large while keeping the cusp height CH small. As a result, the number of irregularities (scallops) given to the machined surface as machined marks can be reduced, and the machined surface accuracy can be improved. In addition, the toolpath length (total machining length) can be reduced by the amount of the larger pick feed, and the machining time can be shortened.

When a cutting test of the work material (S50C) was actually performed using a cutting tool 6A with a replaceable cutting edge equipped with the cutting insert 5A of the present embodiment and a ball end mill of a conventional example, the tool diameter and cutting were performed. It was confirmed that when the speed, the feed amount and the cusp height (scallop height) are set to be the same, the present embodiment can reduce the processing time by about 30% as compared with the conventional example. Further, both the arithmetic mean roughness Ra and the ten-point average roughness Rz of the machined surface were smaller than those of the conventional example in this embodiment, and it was found that the machined surface accuracy was excellent.

Further, a straight cutting edge 13 for connecting the bottom cutting edge 11 and the outer peripheral cutting edge 9 is provided. Therefore, using the straight cutting edge 13, it is possible to perform flat milling (finishing) of the work material, which is difficult to perform with high precision by a conventional ball end mill or the like. In addition, flat milling can be performed efficiently. That is, the straight cutting edge 13 has a function as a finishing blade for eliminating grinds (machined stitches, machined marks). Therefore, according to this embodiment, it is possible to cope with various cutting processes.

From the above, according to the present embodiment, it is possible to perform cutting so that the properties of the machined surface become uniform regardless of the machined portion and 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.

Further, in the present embodiment, the insert body 15 is formed with a screw insertion hole 18 that penetrates the insert body 15 in the thickness direction, and the screw insertion hole 18 is filled with the mounting seat 3 (insert fitting) of the tool body 1. A fixing screw 8 for fixing the cutting insert 5A is inserted into the joint groove 7).
According to the present embodiment, since the center of the screw insertion hole 18 is located on the virtual straight line VL, even when cutting with the bottom cutting edge 11, when cutting with the outer peripheral cutting edge 9. Also, the force for rotating the cutting insert 5A around the screw insertion hole 18 (fixing screw 8) is suppressed.

Specifically, at the time of cutting using the bottom cutting edge 11, the cutting edge normal direction component of the cutting resistance received by the bottom cutting edge 11 acts toward the center of the screw insertion hole 18. Further, at the time of cutting using the outer peripheral cutting edge 9, the cutting edge normal direction component of the cutting resistance received by the outer peripheral cutting edge 9 acts toward the center of the screw insertion hole 18. Therefore, the force for rotating 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 with respect to the mounting seat 3 is reduced. It is suppressed.

As a result, the properties of the machined surface of the work material are stable, and high-precision machining can be realized.
In particular, it is advantageous for high precision in so-called surface-based finishing and intermediate finishing, in which milling is performed on a three-dimensionally shaped component 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, the cutting edge normal direction component of the cutting resistance received by the straight cutting edge 13 acts toward the center of the screw insertion hole 18. Therefore, even at the time of cutting using the straight cutting edge 13, the same action 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 tip end B in the central axis C direction of the outer peripheral cutting edge 9 are connected via one straight cutting edge 13. Therefore, the blade length of the straight cutting edge 13 can be secured to be long, the feed amount when the straight cutting edge 13 is used for cutting can be increased, and the machining efficiency can be improved.

Further, in the present embodiment, of the rake face 19 of the cutting edge portion 4, the rake face portion 12 of the bottom cutting edge 11, the rake face portion 10 of the outer peripheral cutting edge 9, and the rake face portion 14 of the straight cutting edge 13 are flush with each other. Formed on top. Therefore, the axial rake angle and the radial rake angle do not change over the entire length of the cutting edge.
Generally, among the rake faces of the cutting edge portion, the rake face portion of the bottom cutting edge, the rake face portion of the outer peripheral cutting edge, and the like are formed by different flat surfaces and curved surfaces. Since the connection point between the cutting edges is a portion where two cutting edges having different shapes are connected to each other, the axial rake angle and the radial rake angle change. Therefore, at the time of cutting, the cutting load in the vicinity of the connection point between the cutting edges tends to be large.

Therefore, as in the present embodiment, if the rake face portion 12 of the bottom cutting edge 11, the rake face portion 10 of the outer peripheral cutting edge 9, and the rake face portion 14 of the straight cutting edge 13 are formed on the same plane. At the connection point A between the bottom cutting edge 11 and the straight cutting edge 13 and the connection point B between the outer peripheral cutting edge 9 and the straight cutting edge 13, the rake face of the cutting edge is formed by one flat surface. ..
As a result, it is possible to prevent the axial rake angle and the radial rake angle from changing significantly 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. Therefore, the cutting edge strength at the connection portion between the straight cutting edge 13 and the bottom cutting edge 11 and the connecting portion between the straight cutting edge 13 and the outer peripheral cutting edge 9 is remarkably increased, and the tool life is extended.

Further, since the rake face portion 12 of the bottom cutting edge 11, the rake face portion 10 of the outer peripheral cutting edge 9, and the rake face portion 14 of the straight cutting edge 13 are formed on the same plane, it is easy to manufacture the cutting insert 5A. Is. Further, since the recesses (valleys) and the like are not formed between these rake face portions 10, 12, and 14 (connection portions), the catching of chips during cutting is suppressed and the chip discharge property is improved. Will be.

Further, in the present embodiment, when the rake face 19 is viewed from the front, the angle θ1 formed between the first tangent line L1 and the radial reference line RR is 10 to 30 °, and the diameter is 10 to 30 ° with the second tangent line L2. Since the angle θ2 formed between the direction reference line RR and the direction reference line RR is (90 ° −θ1) °, the above-mentioned action and effect become more remarkable. Further, while ensuring the cutting edge strength in the vicinity of the straight cutting edge 13, it becomes easier to deal with the processing site and shape of various work materials.

Specifically, since the angle θ1 is 10 ° or more (the angle θ2 is 80 ° or less), it is possible to prevent the blade length of the straight cutting edge 13 from becoming too long. As a result, the blade lengths of the bottom cutting edge 11 and the outer peripheral cutting edge 9 are secured to be long, and the above-mentioned effect of the present embodiment (effect of increasing the pitch P of the pick feed while keeping the cusp height CH small) can be further enhanced. It can be something special. When the angle θ1 is less than 10 ° (when the angle θ2 exceeds 80 °), the blade length of the straight cutting edge 13 becomes too long, and as a result, the blade lengths of the bottom cutting edge 11 and the outer peripheral cutting edge 9 become short. , The above effects may be difficult to obtain. In addition, in order to make the above-mentioned action and effect more remarkable, it is preferable that the angle θ1 is 12 ° or more (the angle θ2 is 78 ° or less).
Further, since the angle θ1 is 30 ° or less (the angle θ2 is 60 ° or more), it is possible to prevent the blade length of the straight cutting edge 13 from becoming too short. As a result, the blade length of the straight cutting edge 13 can be secured for a long time, and the above-mentioned effect of the present embodiment (effect of performing flat milling with the straight cutting edge 13 with high accuracy and efficiency) can be further enhanced. .. When the angle θ1 exceeds 30 ° (when the angle θ2 is less than 60 °), the blade length of the straight cutting edge 13 becomes too short, and as a result, the above-mentioned effect may be difficult to obtain. In order to make the above-mentioned action and effect more remarkable, the angle θ1 is preferably 28 ° or less (the angle θ2 is 62 ° or more), and 25 ° or less (the angle θ2 is 65 ° or more). Is more desirable.

<Second Embodiment>
Next, the cutting insert 5B according to the second embodiment of the present invention and the cutting edge exchangeable rotary cutting tool 6B provided with the cutting insert 5B will be described with reference to FIGS. 12 to 14.
In the second embodiment, the same parts as the components in the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and the differences will be mainly described.

As shown in FIGS. 12 to 14, the cutting insert 5B and the cutting edge exchangeable rotary cutting tool 6B of the present embodiment are different from the above-described embodiment of the straight cutting edge 13 and the rake face portion 14 provided in the cutting edge portion 4. Etc. are different.
In the present embodiment, the radial outer end (connection point) A of the bottom cutting edge 11 and the tip end (connection point) B of the outer peripheral cutting edge 9 in the central axis C direction are connected via a plurality of straight cutting edges 13. do. Specifically, as shown in FIGS. 14 (a) to 14 (c), the outer end A of the bottom cutting edge 11 in the radial direction and the tip B of the outer peripheral cutting edge 9 in the central axis C direction are two. It is connected via a 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 from 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 moves toward the proximal end side in the central axis C direction from the connection point A toward the outside in the radial direction. It slopes toward and extends. Of the plurality of straight cutting edges 13, the straight cutting edge (second straight cutting edge) 13 connected to the outer peripheral cutting edge 9 is inclined and extends inward in the radial direction from the connection point B toward the tip side. There is.

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

In the present embodiment, the plurality of straight cutting edges 13 (first straight cutting edge 13 and second straight cutting edge 13) are arranged on the outer peripheral side of the tip of the tool with respect to the line segment LS. When the rake face 19 is viewed from the front, the corner portion where the adjacent straight cutting edges 13 are connected to each other is formed so as to form an obtuse angle that becomes convex toward the outer peripheral side of the tip of the tool. Further, the virtual straight line VL passes through the intersection F of the radial reference line RR and the central axial reference line CR and the midpoint M of the line segment LS.

The connection point (the corner portion) between the first straight cutting edge 13 and the second straight cutting edge 13 is arranged on the virtual straight line VL. The connection point between the first straight cutting edge 13 and the second straight cutting edge 13 is arranged on the outer peripheral side of the tip of the tool with respect to the midpoint M of the line segment LS. The first straight line cutting edge 13 and the second straight line cutting edge 13 are formed so as to have a line symmetry shape with each other with the virtual straight line VL as the axis of symmetry. 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 face 19 of the cutting edge portion 4, the rake face portion 12 of the bottom cutting edge 11, the rake face portion 10 of the outer peripheral cutting edge 9, and the rake face portions 14 of the plurality of straight cutting edges 13 are mutually aligned. It is formed on the same plane. In FIGS. 12 and 13, each flank portion of the plurality of straight cutting edges 13 is formed on different planes.

According to the cutting insert 5B and the cutting edge exchange type rotary cutting tool 6B of the present embodiment described above, the same operation and effect as those of the above-described embodiment can be obtained.
Further, in the present embodiment, various finishing processes and the like can be supported by the plurality of straight 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, the finishing process using the first straight cutting edge 13 is performed. , The grind (processed grain, processed mark) can be aligned by the finishing process using the second straight cutting edge 13. Therefore, the grinds imparted to the machined surface of the work material by cutting separately with the plurality of straight cutting edges 13 have the same properties as each other.

<Third Embodiment>
Next, the cutting insert 5C according to the third embodiment of the present invention and the cutting edge exchangeable rotary cutting tool 6C provided with the cutting insert 5C will be described with reference to FIGS. 15 to 17.
In the third embodiment, the same parts as the components in the first and second embodiments are designated by the same reference numerals, the description thereof will be omitted, and the differences will be mainly described.

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

As shown in FIG. 17A, the plurality of straight cutting edges 13 include a straight cutting edge (first straight cutting edge) 13 connected to the bottom cutting edge 11 and a straight cutting edge connected to the outer peripheral cutting edge 9. A straight cutting edge (third straight cutting edge) 13 located between the blade (second straight cutting edge) 13 and the first straight cutting edge 13 and the second straight cutting edge 13 and connecting them. And, are included. The third straight cutting edge 13 is inclined and extends toward the proximal end side in the central axis C direction from the connection point with the first straight cutting edge 13 toward the outside in the radial direction.

The displacement amount of the third straight cutting edge 13 toward the central axis C direction per unit length in the radial direction (that is, the inclination with respect to the radial direction) is larger than the displacement amount of the first straight cutting edge 13, and is the second It is smaller than the displacement amount of the straight cutting edge 13 of 2. In the present embodiment, the displacement amount of the third straight cutting edge 13 and the displacement amount of the line segment LS are the same as 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 arranged on the outer peripheral side of the tip of the tool with respect to the line segment LS. When the rake face 19 is viewed from the front, the corner portion where the adjacent straight cutting edges 13 are connected to each other is formed so as to form an obtuse angle that becomes convex toward the outer peripheral side of the tip of the tool.

The connection point (corner portion) between the first straight cutting edge 13 and the third straight cutting edge 13 and the connection point (corner portion) between the second straight cutting edge 13 and the third straight cutting edge 13 are , It is arranged on the outer peripheral side of the tip of the tool with respect to the line segment LS. Further, the third straight cutting edge 13 is orthogonal to the virtual straight line VL. The first straight line cutting edge 13 and the second straight line cutting edge 13 are formed so as to have a line symmetry shape with each other with the virtual straight line VL as the axis of symmetry. 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 as each other.

According to the cutting insert 5C and the cutting edge exchange type rotary cutting tool 6C of the present embodiment described above, the same operation and effect as those of the above-described embodiment can be obtained.
Further, 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 as each other. The finish processing using the straight cutting edge 13 of the above, the finishing processing using the second straight cutting edge 13, and the finishing processing using the third straight cutting edge 13 are used to make a grind (processed grain, processing mark). Can be aligned.

The blade length of the third straight cutting edge 13 may be different from the blade length of the first and second straight 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 support a wider variety of processing forms.

< Reference example >
Next, the cutting insert 5D according to the reference example of the present invention and the cutting edge exchangeable rotary cutting tool 6D provided with the cutting insert 5D will be described with reference to FIGS. 18 to 20.
In this reference example , the same parts as the components in the first to third embodiments are designated by the same reference numerals, the description thereof will be omitted, and the differences will be mainly described.

As shown in FIGS. 18 to 20, in the cutting insert 5D and the cutting edge replaceable rotary cutting tool 6D of this reference example , the cutting edge portion 4 does not have the straight cutting edge 13 and the rake face portion 14. The configuration is different from the above-described embodiment.

As shown in FIGS. 20 (a) to 20 (c), in this reference example , the outer end (connection point) A in the radial direction of the bottom cutting edge 11 and the tip (connection point) in the central axis C direction of the outer peripheral cutting edge 9 Point) B is directly connected. The radial outer end A of the bottom cutting edge 11 and the tip B of the outer peripheral cutting edge 9 in the central axis C direction 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 in 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 in 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. Therefore, the rake face 19 of the cutting edge portion 4 does not have the rake face portion 14 of the straight cutting edge portion 13. Of the rake face 19, the rake face portion 12 of the bottom cutting edge 11 and the rake face portion 10 of the outer peripheral cutting edge 9 are formed on the same plane.

As shown in FIGS. 18 to 20 (a), the corner portion connecting the outer end A of the bottom cutting edge 11 in the radial direction and the tip B of the outer peripheral cutting edge 9 in the central axis C direction is the tip of the tool. It is formed so as to form an obtuse angle that becomes convex toward the outer peripheral side.
In this reference example , the center of the screw insertion hole 18 is the connection point A and B between 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, and the radial reference. It is located on a virtual straight line VL passing through the intersection F of the line RR and the reference line CR in the central axial direction.

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

According to the cutting insert 5D and the cutting edge exchange type rotary cutting tool 6D of this reference example described above, the same operation and effect as those of the above-described embodiment can be obtained.
In this reference example , since 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 directly connected, the blade length and the outer peripheral edge of the bottom cutting edge 11 are directly connected. The blade length of the cutting edge 9 can be set long (longest). Therefore, the pitch P of the pick feed can be increased while keeping the cusp height CH small. Therefore, it is possible to improve the machining efficiency while maintaining good machining surface accuracy. Further, since the straight cutting edge 13, the rake face portion 14 and the flank portion of the straight cutting edge 13 are not formed, the manufacturing of the cutting insert 5D can be simplified.

Further, in this reference example , since the angle θ1 is 10 ° or more (the angle θ2 is 80 ° or less), the connection points A and B (corners) between the bottom cutting edge 11 and the outer peripheral cutting edge 9 are on the outer peripheral side of the tip of the tool. It is possible to prevent it from being too sharp toward. Therefore, chipping of the cutting edge in the vicinity of the connection points A and B is suppressed. In addition, in order to make the above-mentioned action and effect more remarkable, it is preferable that the angle θ1 is 12 ° or more (the angle θ2 is 78 ° or less).
Further, since the angle θ1 is 30 ° or less (the angle θ2 is 60 ° or more), it is possible to prevent the cutting edge shape of the cutting edge portion 4 from becoming close to the cutting edge shape of the ball end mill as a whole.
That is, each radius of curvature of the bottom cutting edge 11 and the outer peripheral cutting edge 9 can be set sufficiently larger than 1/2 of the blade diameter of the cutting edge portion 4 (1/2 of the tool diameter and the tool radius). The effect of increasing the pitch P of the pick feed described above becomes more remarkable. In order to make the above-mentioned action and effect more remarkable, the angle θ1 is preferably 28 ° or less (the angle θ2 is 62 ° or more), and 25 ° or less (the angle θ2 is 65 ° or more). Is more desirable.

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 illustration of the modified example, the same components as those in the above-described embodiment are designated by the same reference numerals, and mainly different points will be described.

21 (a) to 21 (c) show a modification of the cutting insert 5A of the first embodiment. In this modification, as shown in FIG. 21B, 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 during cutting are efficiently sent from the tool tip to the proximal end side, and the chip discharge property is good. In addition, since the chip discharge property is maintained well, the cutting speed can be increased and the machining efficiency is improved.
Further, since the rake face 19 is formed by one flat surface over the entire blade length of the cutting edge, the axial rake angle of the outer peripheral cutting edge 9, the axial rake angle of the straight cutting edge 13, and the axial direction of the bottom cutting edge 11. The rake angles are all the same angle β. Therefore, the chip evacuation property is stably improved, and the cutting insert 5A can be easily manufactured.
The above-mentioned modification may be applied to the cutting inserts 5B to 5D of the second to third embodiments and the reference example .

Further, in the above-described embodiment and reference example , the screw insertion holes 18 are formed in the cutting inserts 5A to 5D, and the hole center of the screw insertion holes 18 is located on the virtual straight line VL. Not limited. That is, the hole center of the screw insertion hole 18 does not have to be arranged on the virtual straight line VL. However, it is preferable that the hole center of the screw insertion hole 18 is arranged on the virtual straight line VL because the excellent effects described in the above-described embodiments and reference examples can be obtained.
Further, the cutting inserts 5A to 5D in which the screw insertion hole 18 is not formed may be used. In this case, the cutting inserts 5A to 5D are detachably attached to the mounting seat 3 of the tool body 1 by a clamp mechanism or the like. ..

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

Further, in the first to third embodiments, among the rake faces 19, the rake face portion 12 of the bottom cutting edge 11, the rake face portion 10 of the outer peripheral cutting edge 9, and the rake face portion 14 of the straight cutting edge 13 are flush with each other. The example formed above is given. Further, in the reference example , among the rake faces 19, the rake face portion 12 of the bottom cutting edge 11 and the rake face portion 10 of the outer peripheral cutting edge 9 are formed on the same plane. The present invention is not limited to these configurations, and for example, the rake face portions 10, 12, and 14 may be formed on the same curved surface (convex curved surface, concave curved surface). Alternatively, the rake face portions 10, 12, and 14 may be formed by different planes or curved surfaces.

Further, in the above-described embodiments and reference examples , the angle θ1 is 10 to 30 ° and the angle θ2 is (90 ° −θ1) °, but the numerical ranges of the angles θ1 and θ2 are the same as those described above. Not limited.

In the above-described embodiments and reference examples , the material of the substrate (insert body 15) of the cutting inserts 5A to 5D is, for example, cermet, in addition to the cemented carbide containing tungsten carbide (WC) and cobalt (Co). From high-speed steel, titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, and ceramics made of a mixture thereof, cubic boron nitride sintered body, diamond sintered body, polycrystalline diamond or cubic boron nitride. It is also possible to use an ultra-high pressure fired body that fires a hard phase and a bonded phase such as ceramics or an iron group metal under 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 SKD61, it is also possible to use a tool body 1 formed by joining an alloy tool steel such as SKD61 and a cemented carbide.

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 , reference examples, and notes may be combined, and the configurations may be added, omitted, or replaced. , Other changes are possible. Further, the present invention is not limited to the above-described embodiments, but is limited only to the scope of claims.

The cutting insert and the rotary cutting tool with a replaceable cutting edge of the present invention can perform cutting so that the properties of the machined surface are uniform regardless of the machined portion and shape of the work material. Further, in the finishing process, the semi-finishing process, etc., it is possible to obtain good machined surface accuracy over the entire machined surface. Therefore, it has industrial applicability.

1 Tool body 2 Tip 3 Mounting seat 4 Cutting edge 5A-5D Cutting insert 6A-6D Cutting edge replaceable rotary cutting tool 9 Outer peripheral cutting edge 10 Outer peripheral cutting edge rake face 11 Bottom cutting edge 12 Bottom cutting edge rake face Part 13 Straight cutting edge 14 Squeeze surface part of straight cutting edge 15 Insert body 18 Screw insertion hole 19 Squeeze surface A Radial outer end (connection point) of bottom cutting edge
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 L1 First tangent line L2 Second tangent line LS line segment M Midpoint RR Radial direction reference line T1 First right angle triangle T2 Second Right triangle VL Virtual straight line α angle β angle (axial rake angle)
θ1 angle θ2 angle

Claims (10)

A cutting insert that can be attached and detached to the mounting seat formed at the tip of the tool body that is rotated around the central axis.
Plate-shaped insert body and
A cutting edge portion formed on the insert body is provided.
The cutting edge portion is
A bottom cutting edge that is arranged at the tip of the insert body in the central axis direction, extends along the radial direction orthogonal to the central axis, and has an arc shape that is convex toward the tip side in the central axis direction. When,
An outer peripheral cutting edge that is arranged at the radial outer end of the insert body, extends along the central axis direction, and has an arc shape that is convex toward the outside in the radial direction.
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 axis direction are connected via a straight cutting edge.
Looking at the rake face in front,
The bottom cutting edge and the outer peripheral cutting edge have a virtual straight line that intersects the central axis at an angle of 45 ° and extends toward the tip side in the central axis direction as it goes outward in the radial direction as an axis of symmetry. However, the cutting insert is formed so as to have a line-symmetrical shape with each other. The cutting insert according to claim 1.
The insert body is formed with a screw insertion hole that penetrates the insert body in the thickness direction.
A cutting insert in which the center of the screw insertion hole is located on the virtual straight line. A cutting insert that can be attached and detached to the mounting seat formed at the tip of the tool body that is rotated around the central axis.
Plate-shaped insert body and
A cutting edge portion formed on the insert body is provided.
The cutting edge portion is
A bottom cutting edge that is arranged at the tip of the insert body in the central axis direction, extends along the radial direction orthogonal to the central axis, and has an arc shape that is convex toward the tip side in the central axis direction. When,
An outer peripheral cutting edge that is arranged at the radial outer end of the insert body, extends along the central axis direction, and has an arc shape that is convex toward the outside in the radial direction.
With a rake face,
The radius of curvature of the bottom cutting edge and the radius of curvature of the outer peripheral cutting edge are the same as each other.
The radial outer end of the bottom cutting edge and the tip of the outer peripheral cutting edge in the central axis direction are connected via a straight cutting edge.
Looking at the rake face in front,
A straight line extending along the radial direction through the tip in the central axial direction of the bottom cutting edge is defined as a radial reference line.
A straight line extending along the central axial direction through the radial outer end of the outer peripheral cutting edge is defined as a central axial reference line.
The tangent line of the bottom cutting edge at the radial outer end of the bottom cutting edge is defined as the first tangent line.
The tangent line of the outer peripheral cutting edge at the tip of the outer peripheral cutting edge in the central axis direction is defined as the second tangent line.
The intersection of the first tangent line and the radial reference line, the intersection of the first tangent line and the central axial reference line, and the intersection of the radial reference line and the central axial reference line are defined as the intersections. The first right-angled triangle is a right-angled triangle formed by connecting them with a straight line.
The intersection of the second tangent line and the central axial reference line, the intersection of the second tangent line and the radial reference line, and the intersection of the radial reference line and the central axial reference line are defined as the intersections. A right-angled triangle formed by connecting each other with a straight line is used as a second right-angled triangle.
A cutting insert in which the first right triangle and the second right triangle are congruent with each other. The cutting insert according to claim 3.
The insert body is formed with a screw insertion hole that penetrates the insert body in the thickness direction.
The center of the screw insertion hole is the midpoint of a line segment connecting the radial outer end of the bottom cutting edge and the central axial tip of the outer peripheral cutting edge, and the radial reference line and the center. A cutting insert located on a virtual straight line that passes through the intersection with the axial reference line. The cutting insert according to any one of claims 1 to 4.
A cutting insert in which the radial outer end of the bottom cutting edge and the central axial tip of the outer peripheral cutting edge are connected via one straight cutting edge. The cutting insert according to any one of claims 1 to 4.
A cutting insert in which the radial outer end of the bottom cutting edge and the central axial tip of the outer peripheral cutting edge are connected via the plurality of straight cutting edges. The cutting insert according to any one of claims 1 to 6.
The radial outer end of the bottom cutting edge and the central axial tip of the outer peripheral cutting edge are connected via the straight cutting edge.
A cutting insert in which the rake face portion of the bottom cutting edge, the rake face portion of the outer peripheral cutting edge, and the rake face portion of the straight cutting edge are formed on the same plane among the rake faces. The cutting insert according to any one of claims 1 to 7 .
Looking at the rake face in front,
A straight line extending along the radial direction through the tip in the central axial direction of the bottom cutting edge is defined as a radial reference line.
The tangent line of the bottom cutting edge at the radial outer end of the bottom cutting edge is defined as the first tangent line.
The tangent line of the outer peripheral cutting edge at the tip of the outer peripheral cutting edge in the central axis direction is set as the second tangent line.
The angle θ1 formed between the first tangent line and the radial reference line is 10 to 30 °.
A cutting insert in which the angle θ2 formed between the second tangent line and the radial reference line is (90 ° −θ1) °. The cutting insert according to any one of claims 1 to 8 .
The axial rake angle of the outer peripheral cutting edge has a positive value and
A cutting insert in which the axial rake angle of the bottom cutting edge has a positive value. The tool body that can be rotated around the central axis and
The mounting seat formed at the tip of the tool body and
A cutting tool with a replaceable cutting edge, provided with a cutting insert that can be detachably mounted on the mounting seat.
A rotary cutting tool with a replaceable cutting edge, which uses the cutting insert according to any one of claims 1 to 9 as the cutting insert.

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