JP6365363B2 - Cutting insert, cutting insert group and cutting edge exchangeable cutting tool - Google Patents

Description

  The present invention relates to a cutting insert that is detachably attached to an insert mounting seat formed on a tool body of a cutting edge exchangeable cutting tool, a group of cutting inserts constituted by a plurality of such cutting inserts, and the cutting insert. Further, the present invention relates to a cutting edge exchangeable cutting tool.

  As such a cutting insert, for example, in Patent Document 1, there are two end surfaces facing the same opposite direction, and an end surface having a rotational symmetry of 180 ° around a first axis passing through them. A peripheral blade formed by a peripheral side surface extending between the two end surfaces and an intersection line between each end surface and the peripheral side surface, and cutting at least two portions of each peripheral blade Cutting inserts with surrounding blades constituting the blades have been proposed.

  In the cutting insert described in this patent document 1, the surrounding side surface is two main side surfaces facing the same opposite direction, penetrating them and being perpendicular to the first axis. A main side surface having a rotational symmetry of 180 ° around the axis and two identical opposite side surfaces facing therethrough, the first axis and the second axis passing therethrough And a secondary side surface having a rotational symmetry of 180 ° about a third axis orthogonal to each of the four corners, each having two lowered corners and two raised corners have.

  In addition, each secondary side surface merges with the adjacent main side surface at the corner side surface, each corner side surface being one given elevated corner of the two oppositely facing end surfaces. And the other given lowered corner of the two oppositely facing end surfaces, and the adjacent end surfaces, respectively adjacent main side surfaces, corner side surfaces, or A main cutting edge (main cutting edge), a corner cutting edge, or a sub cutting edge (sub cutting edge) is formed at a line of intersection with the sub side surface.

  Each corner side surface has a uniform radius of curvature along its entire length, and therefore all corners have the same radius of curvature as viewed from the direction facing each end surface. Such a cutting insert is attached to a cutting edge-replaceable cutting tool, and cuts a workpiece by a corner blade positioned at the raised corner, and a main cutting edge and a sub cutting edge connected to the corner edge. .

JP 2005-518949 A

  However, in such a cutting insert, between the cutting inserts in which the distance between the two main side faces and the distance between the two sub side faces are equal, the curvature radius of the corner side face, that is, the curvature radius of the corner blade increases, The radius of curvature of lowered corners that are not used for cutting also increases. For this reason, the cutting edge length along the main cutting edge from the corner cutting edge to the end of the main cutting edge on the opposite side to the corner cutting edge has to be shortened to reduce the cutting amount, and the cutting performance is impaired. It will be.

  Here, in order to maintain the cutting performance with the same length from the corner blade to the end of the main cutting blade in order to maintain the cutting performance, the cutting insert having a larger curvature radius of the corner blade has two sub-side surface portions. However, in this case, it is necessary to prepare a tool body in which insert mounting seats of different sizes are formed for each cutting insert having a different radius of curvature of the corner blade. It is inefficient and uneconomical.

  The present invention has been made under such a background, and the cutting edge length to the end of the main cutting edge is shortened even if the radius of curvature of the corner cutting edge is increased between cutting inserts having the same external dimensions. An object of the present invention is to provide a cutting insert that can be prevented, a group of cutting inserts constituted by a plurality of types of such cutting inserts having different curvature radii of corner blades, and a cutting edge-exchangeable cutting tool to which the cutting insert is attached. Yes.

  In order to solve the above-described problems and achieve such an object, the cutting insert of the present invention includes a rectangular plate-like insert body, which includes two rectangular surfaces facing opposite to each other, and Two end faces and two side faces alternately arranged around the quadrilateral surface, and is formed in a 180 ° rotationally symmetric shape around an insert center line passing through the centers of the two quadrilateral surfaces, A main cutting edge having a rake face on the end face is formed on each of the side edges that intersect with at least one of the two end faces, and these main cutting edges are formed on the at least one square face. It is formed so as to gradually protrude toward the two corners located on one diagonal line, and the intersecting ridge line part of the at least one square surface and the two side surfaces is formed by these It is formed in a convex curved surface that is convexly curved between the square surface and the side surface, and this intersecting ridge line portion intersects the two end surfaces, so that the at least one quadrangular surface is on the two corner portions side. The corner portion of the end face that is positioned is formed with a corner blade that is continuous with the main cutting edge in a convex curve shape when viewed from the direction facing the end surface, and the convex curved surface formed by the intersecting ridge line portion is It is characterized in that the radius of curvature gradually decreases with increasing distance from the corner blade along the intersecting ridge line portion.

  Further, in the cutting insert group of the present invention, the interval between the two rectangular surfaces of the insert body, the interval between the two end surfaces, and the interval between the two side surfaces are equal to each other, and the radius of curvature of the corner blade is set. An insert group composed of a plurality of different types of cutting inserts, wherein a cutting insert having a large radius of curvature of the corner blade is a convex curved surface formed by the intersecting ridge line portion than a cutting insert having a small radius of curvature of the corner blade. Is characterized in that the rate of gradually decreasing the radius of curvature of the convex curved surface as the distance from the corner blade along the intersecting ridge line portion is set larger.

  Further, in the cutting edge exchange type cutting tool of the present invention, an insert mounting seat is formed on the outer peripheral portion of the tool body rotated around the axis, and the cutting insert of the present invention as described above is formed on the insert mounting seat. One of the two end faces is detachably attached with the tool rotating direction.

  In the cutting insert of the present invention configured as described above, two corners formed on the intersecting ridge line portion of the at least one square surface and the two side surfaces of the insert main body and projecting from the at least one square surface. The convex curved surface that forms the corner blade at the corner portion of the end surface located on the portion side is formed so that the radius of curvature gradually decreases as the corner blade is separated from the corner blade along the intersecting ridge line portion. Even if the curvature radius is increased, it is possible to prevent the curvature radius of the corner portion connected to the main cutting edge from increasing on the opposite side of the intersection ridge line portion between the two end faces.

  For this reason, in the cutting inserts constituting the cutting insert group of the present invention, even in a cutting insert having a large radius of curvature of the corner blade, the convex curved surface formed by the intersecting ridge line portion is separated from the corner blade along the intersecting ridge line portion. By setting the rate at which the radius of curvature of the convex curved surface is gradually smaller than that of the insert having a small radius of curvature of the corner blade, the cutting edge length along the main cutting edge from the corner blade to the main cutting edge is The cutting depth can be made substantially the same as that of the cutting insert having a small curvature radius, and the cutting depth can be secured and efficient cutting can be performed. Further, as described above, the interval between the two rectangular surfaces, the interval between the two end surfaces, and the interval between the two side surfaces can be made equal to each other, that is, the outer dimensions of the insert body can be made equal. The tool body can be used efficiently and economically.

  Here, the insert main body is formed in a reverse-inverted symmetrical shape with respect to the two rectangular surfaces, and the corner blades are formed on two corner portions located on one diagonal line of each of the two side surfaces. In this case, the corner blade and the main cutting blade can be used a total of four times with one insert body, which is more efficient and economical. At this time, a flat seating surface is formed on these two side surfaces along the other diagonal line of the side surface, thereby preventing interference with the corner blades and the crossed ridge line portions and securing a large area seating surface. A stable cutting insert can be mounted by attaching the insert main body with the seating surface in contact with the flat wall surface of the insert mounting seat.

  Further, at this time, a secondary flank is formed between the intersecting ridge line portion and the seating surface on the two side surfaces, and the corner blades are formed on the side ridges of the two end surfaces intersecting the sub flank. By forming the secondary cutting edge that is connected to, the machining surface intersecting with the machining surface formed by the main cutting edge can be smoothed when, for example, it is used for a cutting tool with an exchangeable edge. In addition, by making the auxiliary flank and the seating surfaces different from each other, the above-described stable cutting insert can be attached regardless of the inclination of the auxiliary flank. Even in this case, according to the cutting insert and the group of cutting inserts of the present invention, if the width of the seating surface is the same, along the auxiliary cutting edge from the corner blade to the end opposite to the corner cutting edge of the auxiliary cutting edge. The cutting edge length in the same direction can be made substantially equal even between cutting inserts having different curvature radii of corner blades.

  As described above, according to the present invention, it is possible to perform efficient cutting with a constant cutting amount even between cutting inserts having different curvature radii of corner blades, and the outer dimensions of the insert main body are also constant. Cutting can be performed with a corner blade having different radii of curvature in different types of tool bodies.

It is a perspective view which shows one Embodiment of the cutting insert of this invention. It is the side view which looked at embodiment shown in FIG. 1 from the insert centerline direction. It is a top view of embodiment shown in FIG. It is a front view of embodiment shown in FIG. It is ZZ sectional drawing in FIG. It is a perspective view which shows one Embodiment of the blade-tip-exchange-type cutting tool of this invention which attached embodiment shown in FIG. It is the side view which looked at embodiment shown in FIG. 6 from the axial direction. It is a top view of embodiment shown in FIG. It is a front view of embodiment shown in FIG. It is a perspective view which shows the 1st modification of embodiment shown in FIG. 1 thru | or 5 which comprises one Embodiment of the cutting insert group of this invention. It is the side view which looked at the modification shown in FIG. 10 from the insert centerline direction. It is a top view of the modification shown in FIG. It is a front view of the modification shown in FIG. It is ZZ sectional drawing in FIG. It is a perspective view which shows the 2nd modification of embodiment shown in FIG. 1 thru | or 5 which comprises one Embodiment of the cutting insert group of this invention. It is the side view which looked at the modification shown in FIG. 15 from the insert centerline direction. It is a top view of the modification shown in FIG. It is a front view of the modification shown in FIG. It is ZZ sectional drawing in FIG.

  FIGS. 1 to 5 show an embodiment of the cutting insert of the present invention, and FIGS. 6 to 9 show an embodiment of the cutting edge replaceable cutting tool of the present invention to which the cutting insert of this embodiment is attached. Further, FIGS. 10 to 19 show modifications of the embodiment shown in FIGS. 1 to 5 which constitute one embodiment of the cutting insert group of the present invention. The cutting insert of the present embodiment includes a rectangular plate-like insert body 1 formed of a hard material such as cemented carbide, that is, the insert body 1 includes two rectangular surfaces 2 facing opposite to each other, There are two end faces 3 and two side faces 4 alternately arranged around the circumference of the rectangular face 2.

  The two rectangular surfaces 2 of the insert main body 1 have mounting holes 1A that penetrate the insert main body 1 with an insert center line (first center line) L1 passing through the centers of the two rectangular surfaces 2 open. The insert body 1 is formed in a 180 ° rotationally symmetrical shape around the insert center line L1, that is, when the insert body 1 is rotated 180 ° around the insert center line L1, the insert body 1 was in the original position. Overlapping shape. In addition, the rectangular surface 2 is formed in a planar shape perpendicular to the insert center line L1 around the opening of the mounting hole 1A.

  Further, the insert main body 1 in the present embodiment is formed in a front-back inversion symmetrical shape with respect to these two rectangular surfaces 2, that is, a second center line passing through the centers of the two end surfaces 3 perpendicular to the insert center line L 1. In addition to being formed 180 degrees rotationally symmetrical around L2, it is also formed 180 degrees rotationally symmetrical around the third centerline L3 passing through the centers of the two side surfaces 4 perpendicularly to the insert centerline L1.

  A main cutting edge 5 having a rake face on the end surface 3 is formed on each side ridge portion intersecting the two quadrangular surfaces 2 of the two end surfaces 3, and an opening portion of the mounting hole 1 </ b> A on the quadrangular surface 2. The periphery is a flank of the main cutting edge 5, and a total of four main cutting edges 5 are formed in this embodiment. The interval between the two end surfaces 3 and the interval between the two side surfaces 4 are set to be larger than the interval between the two rectangular surfaces 2, that is, the cutting insert of this embodiment is a vertical blade type cutting insert. It is.

  These main cutting edges 5 form a straight line, and two corners located on one diagonal line with respect to one quadrangular surface 2 (lower right and upper left corners in the front quadrangular surface 2 in FIG. 2). ), The rectangular surface 2 is formed so as to gradually protrude in the direction of the second center line L2 as shown in FIG. 2, including the intersecting ridge line portion 6 with the two side surfaces 4 described below. When viewed from the direction of the insert center line L1, the two corners are formed in a parallelogram shape having acute corners. However, the two rectangular surfaces 2 are arranged such that the acute angle portions are alternately positioned when viewed from the direction of the insert center line L1.

  The intersecting ridge line portion 6 between the two quadrangular surfaces 2 and the two side surfaces 4 is formed as a convex curved surface that curves convexly between the quadrangular surfaces 2 and the side surfaces 4. And this intersection ridgeline part 6 cross | intersects with the two end surfaces 3, The corner part C located in the said 2 acute angle part side of the square surface 2 among the four corner parts C of the end surface 3 has this end surface. As shown in FIG. 3, the corner blade 7 that is continuous with the main cutting edge 5 is formed as shown in FIG. Further, the convex curved surface formed by the intersecting ridge line portion 6 serving as a flank of the corner blade 7 is formed such that the radius of curvature gradually decreases as the distance from the corner blade 7 increases along the intersecting ridge line portion 6.

  Here, in the present embodiment, the convex curved surface formed by the intersecting ridge line portion 6 is a single convex conical surface having a central axis along the direction in which the intersecting ridge line portion 6 extends. Is formed such that the radius from the central axis gradually decreases as the distance from the corner blade 7 which is an intersecting ridge line with the end surface 3 increases. The convex conical surface formed by the intersecting ridge line portion 6 is in contact with the periphery of the flat mounting hole 1A opening of the quadrangular surface 2 at the generatrix, so that the central axis of the convex conical surface is the intersection ridge line portion. As the distance from the corner blade 7 increases along the direction 6, the distance from the second center line L 2 increases when viewed from the direction of the insert center line L 1 and from the direction of the third center line L 3. In addition, the intersecting ridge line portion 6 extends until reaching an obtuse angle corner portion retreated in the second center line L2 direction of the quadrangular surface 2 having the parallelogram shape as described above, and the end surface 3 on which the corner blade 7 is formed. Intersects the corner portion C located on the obtuse angle portion side of the opposite end face 3.

  Furthermore, in this embodiment, since the insert body 1 is formed in a reverse-inverted symmetrical shape with respect to the two rectangular surfaces 2, as shown in FIG. 4, the corner blade as viewed from the direction of the third centerline L 3 facing the side surface 4. 7 is formed on the two corners located on one diagonal line of each of the two side surfaces 4. Further, a planar seating surface 4A is formed on these two side surfaces 4 along the other diagonal line of the side surface 4, and this seating surface 4A is in the third center line L3 in the present embodiment. It is a vertical plane.

  Furthermore, on these two side surfaces 4, a secondary flank 4B is formed between the intersecting ridge line portion 6 and the seating surface 4A, and the side edges of the two end surfaces 3 intersecting the sub flank 4B. The part is formed with a sub-cutting blade 8 connected to the corner blade 7. This sub-cutting edge 8 is also linear like the main cutting edge 5, and the second side as it goes toward the two corners located on the one diagonal line where the corner edge 7 is arranged on one side face 4. It is formed so as to gradually protrude in the direction of the center line L2.

  The main cutting edge 5 and the auxiliary cutting edge 8 are arranged in a direction intersecting at an obtuse angle slightly larger than a right angle when viewed from the direction of the second center line L2 facing the end face 3, and therefore in the same direction. The corner blade 7 is in contact with the main cutting edge 5 and the auxiliary cutting edge 8 in a substantially convex arc shape with a central angle slightly smaller than a right angle. The seating surface 4A and the auxiliary flank 4B intersect at an obtuse angle close to a flat angle. Further, the corner blade 7 also extends in the direction of the second center line L2 in the vicinity of the center of the convex arc when viewed from the direction of the second center line L2 when viewed from the direction of the insert center line L1 and the direction of the third center line L3. It protrudes most and is formed in the convex curve shape which touches the main cutting edge 5 and the subcutting edge 8. FIG.

  Further, in the present embodiment, the two end surfaces 3 on which the main cutting edge 5, the corner blade 7 and the auxiliary cutting edge 8 are formed at the side ridge portion are formed from the side ridge portion to the end surface 3 as shown in FIG. The first inclined surface 3A that inclines so as to recede in the direction of the second center line L2 as it goes inward, and the inner side of the first inclined surface 3A is steeper than the first inclined surface 3A toward the inside of the end surface 3 Accordingly, a second inclined surface 3B that is inclined so as to recede in the direction of the second center line L2 and a flat surface 3C that is orthogonal to the second center line L2 are formed further inside the second inclined surface 3B. The width of the first inclined surface 3A is the largest on the inside of the corner blade 7 and is a constant width slightly smaller than the inside on the inside of the main cutting blade 5, and gradually increases as the distance from the corner blade 7 on the inside of the auxiliary cutting blade 8 increases. It is formed to be narrow.

  The cutting insert configured as described above is detachably attached to the tool body 11 in one embodiment of the cutting edge-exchangeable cutting tool of the present invention shown in FIGS. 6 to 9, for example, and used for cutting a work material. It is done. The blade-tip-exchangeable cutting tool of this embodiment is a blade-tip-exchangeable cutting tool in which an insert mounting seat 12 is formed on the outer peripheral portion of the tool body 11 that is rotated around the axis O, and particularly with the axis O as the center. A plurality of insert mounting seats 12 are formed on the outer peripheral portion of the disk-shaped tool main body 11, and the cutting insert having the above-described configuration is formed on these insert mounting seats 12 with one of the two end surfaces 3 of the insert main body 1. It is a blade-tip-exchange-type side cutter that is detachably attached in the tool rotation direction T.

  A hole 13 with a key groove is formed in the tool body 11 along the axis O, and the tool body 11 rotates around the axis O by being attached to the spindle of the machine tool through the key groove hole 13. While being rotated in the direction T, the workpiece is fed relative to the work material in a direction orthogonal to the axis O, and the work material is grooved by the cutting insert. On the outer peripheral portion of the tool body 11, the same number of insert pockets 14 as the insert mounting seats 12 recessed in a U shape on the inner peripheral side are formed at equal intervals in the circumferential direction. Insert mounting seats 12 are formed so as to be connected to the opposite side.

  The insert mounting seat 12 includes a bottom surface facing the outer periphery of the flat tool body 11, a wall surface facing the tool rotation direction T, and a wall surface facing the axis O direction, and the tool body 11 outer periphery side, the tip pocket 14 and the tool body. 11 is formed as a recess that opens in one circular surface, but the circular surface of the tool body 11 in which the insert mounting seat 12 is thus opened is alternately a circular surface on the opposite side in the circumferential direction of the tool body 11. ing. In addition, a screw hole is formed at the center of the bottom surface of the insert mounting seat 12, and the wall surface facing the tool rotation direction T has a size that can be inserted into the second inclined surface 3 </ b> B of the end surface 3 of the insert body 1. It is formed in the part.

  In such an insert mounting seat 12, the cutting insert of the above embodiment has one of the two rectangular surfaces 2 in close contact with the bottom surface and the opposite rectangular surface 2 on the outer peripheral side of the tool body 11. And the one end face 3 is directed in the tool rotation direction T as described above, and the flat surface 3C of the end face 3 opposite to the one end face 3 faces the tool rotation direction T of the insert mounting seat 12 In addition, the seating surface 4A of one side surface 4 is brought into contact with the wall surface facing the direction of the axis O, and the opposite side surface 4 is projected from the circular surface of the tool body 11 opened by the insert mounting seat 12. Be seated. And the cutting insert is detachably attached to the insert attachment seat 12 by screwing the clamp screw 15 inserted into the attachment hole 1A into the screw hole formed on the bottom surface.

  In the cutting insert thus mounted, the corner blade 7 connected to the main cutting edge 5 located on the outer peripheral side of the tool body 11 of the end face 3 directed in the tool rotation direction T protrudes most toward the tool rotation direction T. The main cutting edge 5 connected to 7 is arranged slightly inclined so as to go to the opposite side of the tool rotation direction T as the distance from the corner edge 7 increases. Further, the main cutting edge 5 is formed by cutting inserts attached to insert mounting seats 12 that open alternately on a circular surface on the opposite side in the circumferential direction of the tool body 11, and on one cylindrical surface centering on the axis O. Are overlapped in the rotation locus around the axis O so as to be positioned at the position of the center and used for cutting. Further, a clearance angle is given to the rectangular surface 2 connected to the main cutting edge 5 so as to go to the inner peripheral side of the tool body 11 as it goes to the opposite side of the tool rotation direction T.

  Further, among the auxiliary cutting edges 8 formed on the side ridges of the end surface 3 directed in the tool rotation direction T, the auxiliary flank 4B formed on the side surface 4 of the insert body 1 protruding from the circular surface of the tool body 11. The secondary cutting edge 8 connected to (the secondary cutting edge 8 connected to the corner blade 7 that protrudes most in the tool rotation direction T side) is spaced apart from the corner blade 7 in the direction of the tool rotation direction T toward the inner peripheral side of the tool body 11. A machined surface formed by the main cutting edge 5 that is slightly inclined so as to be directed to the opposite side and is arranged so as to be positioned on one plane orthogonal to the axis O in each circular surface from which the side surface 4 protrudes. Is used for cutting so as to finish smoothly. Furthermore, a clearance angle is also given to the side surface 4 including the auxiliary flank 4B of the auxiliary cutting edge 8 so as to go inward in the axis O direction of the tool body 11 as it goes to the opposite side of the tool rotation direction T.

  Furthermore, a corner blade 7 that is formed between the main cutting edge 5 and the auxiliary cutting edge 8 that is used for these cutting operations and protrudes most toward the tool rotation direction T is also used for the cutting processing. A clearance angle is given to the intersecting ridge line portion 6 between the quadrangular surface 2 and the side surface 4 that extends to the inner peripheral side of the tool main body 11 and the inner side in the axis O direction toward the opposite side of the tool rotation direction T. Therefore, when grooving is performed with such a cutting edge exchangeable cutting tool (side cutter), the corner between the groove bottom surface formed by the main cutting edge 5 and the two groove wall surfaces finished by the sub cutting edge 8 is used. The corners are formed by the corner blades 7 in a concave curved surface shape in contact with the groove bottom surface and the groove wall surface.

  In such grooving, when a concave curved surface having a different curvature radius is formed at the corner between the groove bottom surface and the groove wall surface, the radius of curvature of the corner blade 7 at the corner portion C of the end face 3 is set as the cutting insert. It will be exchanged for a different one. FIGS. 10 to 19 show modifications of the above-described embodiment constituting the cutting insert group of one embodiment of the present invention in which the radius of curvature of the corner blade 7 is different, and FIGS. FIGS. 15 to 19 show a first modification of the embodiment in which the radius of curvature of the corner blade 7 is larger than that of the embodiment shown in FIGS. 1 to 5. FIGS. 15 to 19 are shown in FIGS. 2 shows a second modification of the embodiment in which the radius of curvature of the corner blade 7 is smaller than that of the embodiment, and the same reference numerals are allotted to portions common to the embodiment shown in FIGS. 1 to 5. Therefore, the description is omitted.

  The cutting inserts according to the first and second modified examples and the embodiment described above include the distance between the two rectangular surfaces 2 of the insert body 1 in the direction of the insert center line L1 and the first surface between the flat surfaces 3C of the two end surfaces 3. The distance between the two centerlines L2 and the distance between the seating faces 4A of the two side faces 4 in the third centerline L3 direction are set to be equal to each other, and therefore, the tool body of one common cutting edge exchangeable cutting tool 11 can be detachably attached to the insert mounting seat 12 formed on the head 11. In the cutting inserts constituting these cutting insert groups, the cutting insert having a large curvature radius of the corner blade 7 has a convex curved surface formed by the intersecting ridge portion 6 than the cutting insert having a small curvature radius of the corner blade 7. The rate at which the radius of curvature of the convex curved surface gradually decreases as the distance from the corner edge 7 along the intersecting ridge line portion 6 increases.

  Therefore, in the cutting insert and the cutting insert group configured as described above, the corner blade 7 used for cutting is formed even when the corner blade 7 has a large curvature radius, for example, the cutting insert of the first modified example. Since it is possible to prevent an increase in the radius of curvature of the corner portion C where the intersecting ridge line portion 6 connected to the corner blade 7 intersects at the end surface 3 opposite to the end surface 3, the corner blade at the opposite end surface 3 is prevented. The cutting edge length along the main cutting edge 5 from 7 to the main cutting edge 5 can be made substantially equal to the cutting insert of the embodiment or the second modification.

  For this reason, in these cutting inserts, the amount of cutting can be made constant, and the cutting depth can be secured and efficient cutting can be performed. Specifically, for example, in the cutting edge-exchangeable cutting tool of the above-described embodiment, there is a situation in which the main cutting blade 5 cannot be overlapped between the cutting inserts of the insert mounting seat 12 that opens to the two circular surfaces of the tool body 11. This can be prevented, and there is no need to supplement the space between these main cutting edges 5 with a cutting edge of another cutting insert.

  Further, in the cutting inserts constituting the cutting insert group, as described above, the interval between the two rectangular surfaces 2, the interval between the flat surfaces 3C of the two end surfaces 3, and the interval between the seating surfaces 4A of the two side surfaces 4 are equal to each other. Since the outer dimensions of the insert main body 1 are set to be equal, that is, the part contacting the insert mounting seat 12 is set equal, it can be used by being attached to one common tool main body 11. For this reason, there is no need to prepare a separate tool body for each cutting insert having a different radius of curvature of the corner blade 7, which is efficient and economical.

  Further, in the present embodiment, the intersecting ridge line portion 6 between the quadrangular surface 2 and the side surface 4 is formed in a convex conical surface shape, and the central axis of the convex conical surface is a corner blade 7 along the intersecting ridge line portion 6. As they are separated from each other, they are inclined so as to be away from the second center line L2 when viewed from the direction of the insert center line L1 and when viewed from the direction of the third center line L3. For this reason, for example, as in the cutting insert described in Patent Document 1, the corner side surface has a uniform radius of curvature over its entire length and extends parallel to the first axis. Even if the second center line L2 of the insert main body 1 is not so inclined with respect to the work material, a sufficient clearance angle can be given to the corner blade 7.

  Therefore, if the corner angle of the corner blade 7 is the same, the rake angle can be increased to the positive angle side, so that a sharp cutting edge can be given to the corner blade 7 to reduce the cutting resistance. Conversely, if the rake angle of the corner blade 7 is the same, the blade angle can be increased to ensure the strength of the blade edge, and the occurrence of defects or the like can be prevented. The same applies to the main cutting edge 5 and the auxiliary cutting edge 8.

  In particular, in the rolling tool that is the cutting edge exchangeable cutting tool of the present embodiment, the rectangular surface 2 serving as the flank face of the main cutting edge 5 and the intersecting ridge line portion 6 serving as the flank face of the corner blade 7 are used as the main cutting edge 5. In addition, it must be placed inside the rotation trajectory around the axis O of the corner blade 7, and depending on the outer dimensions of the insert body 1 and the outer diameter of the tool body 11, a sufficient clearance angle is ensured unless the insert body 1 is tilted greatly. However, the cutting insert having the above-described configuration that can secure the clearance angle without tilting the insert main body 1 as described above is suitable, while the rake angle and the blade angle may be restricted.

  In the cutting insert of the present embodiment, the convex curved surface formed by the intersecting ridge line portion 6 between the quadrangular surface 2 and the side surface 4 is formed in a convex conical surface, but the cross section along the central axis forms a convex curve, for example. Thus, it may be a convex curved surface in which the radius from the center line decreases as the distance from the corner blade 7 increases, and the section perpendicular to the center axis forms an ellipse or an ellipse and is separated from the corner blade 7. A convex curved surface whose curvature radius becomes smaller according to

  Further, corner blades 7 are formed at the corner portions C of the end surfaces 3 positioned on the two protruding corners of the two rectangular surfaces 2 of the insert body 1, and a total of four corner blades 7 are formed in one cutting insert. However, the corner blade 7 is formed only in the corner portion C of the end surface 3 on the two corners protruding from the one square surface 2, and the opposite square surface is attached to the insert mounting seat 12. It may be a plane only for the purpose.

  However, in such a case, only the corner blade 7 and the main cutting edge 5 can be used only twice, whereas the insert body 1 has a reverse-inverted symmetrical shape with respect to the two rectangular surfaces 2 as in this embodiment. If the corner blades 7 are formed on the two corners on the two side surfaces 4 on the two diagonal sides, the corner blades 7 and the main four times in one insert body 1 are formed. The cutting blade 5 can be reused.

  In particular, when the insert body 1 is thus formed in a reverse-symmetrical shape with respect to the two rectangular surfaces 2, the planar seating surface 4 </ b> A along the other diagonal line of the side surface 4 as in this embodiment. By forming this, it is possible to prevent interference with the corner blade 7 and the intersecting ridge line portion 6 and to secure a large area on the seating surface 4A. Therefore, the insert body 1 can be stably inserted by bringing such a seating surface 4A into contact with the wall surface of the insert mounting seat 12 facing the flat axis O direction, like the cutting edge exchangeable cutting tool of the present embodiment. It can be attached to the mounting seat 12.

  Further, when the seating surface 4A is formed along the other diagonal line of the side surface 4 in this way, a sub-flank 4B is formed in the gap between the seating surface 4A and the intersecting ridge line portion 6, By forming the auxiliary cutting edge 8 connected to the corner edge 7 at the side ridge portion of the end face 3 intersecting with the auxiliary flank 4B, the grooving is performed by the cutting edge exchangeable cutting tool (side cutter) of the present embodiment as described above. When performing, the groove wall surface of the groove formed by the main cutting edge 5 can be finished smoothly by the sub cutting edge 8.

  Further, by making the sub-flank 4B and the seating surface 4A different from each other so as to intersect at an obtuse angle as in this embodiment, the above-described stable attachment of the insert body 1 by the seating surface 4A is maintained. However, the finishing cutting can be performed by reliably positioning the auxiliary cutting edge 8 used for the cutting on one plane orthogonal to the axis O. According to the cutting insert and the cutting insert group having the above-described configuration, even when the auxiliary cutting edge 8 is formed in this manner, cutting inserts having different curvature radii of the corner edge 7 can be used as long as the seating surface 4A has the same width. The cutting blade length in the direction along the secondary cutting edge 8 from the corner cutting edge 7 to the secondary cutting edge 8 can be made substantially equal.

  In addition, although the cutting edge replaceable cutting tool of the present embodiment is obtained by attaching the cutting insert having the above configuration to a side cutter which is a cutting edge replaceable cutting tool, the same cutting edge replaceable cutting tool can be used, for example, an axis line. A chip discharge groove is formed on the outer periphery of the tip of the cylindrical tool body that rotates around, and the cutting insert having the above configuration is mounted on the insert mounting seat formed on the opposite side of the chip discharge groove from the tool rotation direction. Further, the present invention can be applied to shoulder cutting and grooving of a work material by applying the present invention to an end mill with a replaceable cutting edge. In this case, a plurality of insert mounting seats may be formed along the chip discharge grooves to attach the cutting inserts, and concave curved surfaces having different radii of curvature are formed at the corners of the shoulder and groove processing bottom and wall surfaces. When forming, the cutting insert at the tip of the tool body may be replaced with one having a different curvature radius of the corner blade 7.

DESCRIPTION OF SYMBOLS 1 Insert body 2 Square surface of the insert body 1 3 End surface of the insert body 1 4 Side surface of the insert body 1 4A Seating surface 4B Secondary relief surface 5 Main cutting edge 6 Cross ridge line part of the square surface 2 and the side surface 7 Corner blade 8 Secondary Cutting blade 11 Tool body 11
12 Insert mounting seat L1 Insert center line (first center line)
L2 2nd center line L3 3rd center line C Corner part of end face 3 Axis line of tool body 11 T Tool rotation direction

Claims (5)

The insert body has a rectangular plate-like insert body, and the insert body has two square surfaces facing opposite to each other, and two end surfaces and two side surfaces alternately arranged around the square surface. Then, it is formed in a 180 ° rotationally symmetric shape around the insert center line passing through the centers of the two rectangular surfaces,
A main cutting edge having a rake face on the end face is formed on each of the side edges that intersect with at least one of the two end faces, and these main cutting edges are formed on the at least one square face. It is formed so as to gradually protrude toward the two corners located on one diagonal line,
The intersecting ridge line portion between the at least one quadrangular surface and the two side surfaces is formed into a convex curved surface that curves in a convex shape between the square surface and the side surface, and the intersecting ridge line portion is the two end surfaces. The corner portion of the end face located on the two corners side of the at least one quadrangular surface has a convex curve shape when viewed from the direction facing the end face, thereby forming the main cutting edge. A continuous corner blade is formed,
The cutting insert, wherein the convex curved surface formed by the intersecting ridge line portion is formed such that the radius of curvature gradually decreases as the distance from the corner blade increases along the intersecting ridge line portion. The insert body is formed in a reverse-inverted symmetrical shape with respect to the two rectangular surfaces, and the corner blades are formed on two corners located on one diagonal line of each of the two side surfaces,
The cutting insert according to claim 1, wherein a planar seating surface is formed on the two side surfaces along one other diagonal line of the side surfaces.   On the two side surfaces, a sub-flank is formed between the intersecting ridge line portion and the seating surface, and the side ridge portions of the two end surfaces intersecting the sub-flank are connected to the corner blade. The cutting insert according to claim 2, wherein a sub cutting edge is formed. The plurality of types of claims 1 to 5, wherein an interval between the two rectangular surfaces of the insert body, an interval between the two end surfaces, and an interval between the two side surfaces are equal to each other, and the corner blades have different curvature radii. It is an insert group constituted by the cutting insert according to any one of 3,
The cutting insert having a large radius of curvature of the corner blade is more prone to the convex curved surface formed by the intersecting ridge line portion separating from the corner blade along the intersecting ridge line portion than the cutting insert having a smaller radius of curvature of the corner blade. A cutting insert group in which a ratio of gradually decreasing the curvature radius of the curved surface is set to be large. An insert mounting seat is formed on the outer periphery of the tool body rotated around the axis,
The cutting insert according to any one of claims 1 to 3 is detachably attached to the insert mounting seat with one of the two end faces directed in the tool rotation direction. The cutting edge exchangeable cutting tool.

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