JP2016032860A - Cutting insert and tooth point replaceable cutting tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively use a cutting blade formed on respective side ridge parts of a polygonal-shaped face of a polygonal-plate insert body, and promote smooth chip discharge.SOLUTION: A polygonal-plate insert body 1 is provided. On respective side ridge parts of at least one polygonal face of the insert body 1, cutting blades 4 having a rake face 3 on the polygonal face are respectively formed. These cutting blades 4 are configured so that, from a first end 4A of each cutting blade 4 on one circumferential direction of the polygonal face toward a second end 4B opposite to the first end 4A, the respective cutting blade gradually project. The cutting blades 4 formed on adjacent side ridge parts of the polygonal face are configured so that, the first end 4A of one cutting blade 4 and the second end 4B of the other cutting blade 4 face each other, via a step part 7 which becomes hollow from the second end 4B of the other cutting blade 4 toward the first end 4A of the one cutting blade 4.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a cutting insert that is detachably attached to a cutting edge exchange type cutting tool such as a blade edge exchange type end mill, and a cutting edge exchange type cutting tool to which the cutting insert is attached.

  For example, Patent Document 1 discloses a positive type cutting insert having a square plate-like insert body in a plurality of torsion grooves formed in a tool body. A tool that is detachably attached by a clamp screw in such a way that a positive axial rake angle is given to a cutting blade that is directed toward the outer peripheral side of the tool body has been proposed. Since the cutting insert has a square plate shape, a cutting edge is formed on each of the four side ridges on the square surface on which the rake face is formed, and the insert body is placed in the circumferential direction of the square surface. By rotating and reattaching, it is usually possible to use the cutting blade four times with one cutting insert.

Japanese Utility Model Publication No. 61-199314

  By the way, when shouldering or grooving a workpiece with such an edge-changing cutting tool, the cutting edge is given a positive rake angle in the axial direction. From the end directed to the workpiece, it bites into the work material and generates chips. Chips generated by the cutting blade are dragged on the rake face to receive resistance and are rolled up into a string winding shape while extending to the rear end side of the tool body along the cutting blade and directed toward the rear end side of the tool body. The edge of the cutting edge leaves the rake face away from the work material and is discharged through the twisted groove.

  However, in the cutting insert described in Patent Document 1, the square surface on which the rake face is formed is a flat surface, and cutting edges are formed on the four side ridges of the flat square surface as described above. Has been. Therefore, the chips generated by the cutting edge protruding to the outer peripheral side of the tool body may interfere with or be pressed strongly against the outer peripheral end of the cutting edge directed to the rear end side of the tool body adjacent to the cutting edge. However, it will leave the rake face.

  For this reason, for example, when the work material is a difficult-to-cut material such as titanium, even if the insert body is a hard cemented carbide, the above-mentioned end portion of the cutting blade directed toward the rear end side of the tool body is damaged. As a result, there is a possibility that the cutting edge cannot be used for cutting by projecting it toward the outer periphery of the tool body. Moreover, chip | tip discharge property will also be impaired by pressing a chip | tip strongly in this way.

  The present invention has been made under such a background, and can effectively reuse the cutting blades formed on each side ridge portion of the polygonal surface of the polygonal plate-like insert body and can smoothly cut chips. It is an object of the present invention to provide a cutting insert capable of prompting discharge and a cutting edge exchangeable cutting tool to which the cutting insert is detachably attached.

  In order to solve the above problems and achieve such an object, the cutting insert of the present invention comprises a polygonal plate-like insert body, and each side ridge portion of at least one polygonal surface of the insert body. Are formed with cutting edges each having a rake face on the polygonal surface, and these cutting edges are formed from the first end of the cutting edge in one circumferential direction of the polygonal surface. Inclining so as to gradually rise as it goes to the second end opposite to the first end, and the cutting edges formed on the adjacent side ridges of the polygonal surface are The first end portion of the cutting blade and the second end portion of the other cutting blade are directed from the second end portion of the other cutting blade toward the first end portion of the one cutting blade. It is characterized by facing each other through a recessed stepped portion.

  Further, the cutting edge replaceable cutting tool of the present invention is a cutting edge replaceable cutting tool in which such a cutting insert is detachably attached to the outer periphery of the tip end of a tool body that is rotated around an axis. The one cutting edge is projected to the outer peripheral side of the tool body to give a positive axial rake angle, and the first end of the cutting edge is directed to the tip side of the tool body. The second end portion is directed to the rear end side of the tool body.

  The cutting insert configured as described above is attached to the cutting edge-exchangeable cutting tool in this manner, so that the cutting blade that is projected to the outer peripheral side of the tool main body and used for cutting is the first on the outer peripheral tip side of the tool main body. The tip is inclined so as to gradually rise from the end of the outer edge toward the second end on the outer peripheral rear end side, and the chips generated by the cutting edge are pushed up along the inclination of the cutting edge while Rub the rake face towards the end of the. The cutting edges formed on adjacent side ridges of the polygonal surface are such that the first end of one cutting edge and the second end of the other cutting edge are Since they face each other through a stepped portion that is recessed from the second end portion toward the first end portion of one of the cutting edges, the chips are adjacent to the rear end side of the tool body of the cutting edge used for cutting. It is discharged without interfering with the first end of the cutting blade.

  Moreover, since the 1st edge part is located in the circumference direction of one of the said polygonal surfaces in each cutting blade, and the 2nd edge part is located on the opposite side, the insert main body is rotated. Even when reattaching, the first end is directed to the tool body front end side and the second end is directed to the rear end side to prevent chip interference as described above. Therefore, even if the work material is a difficult-to-cut material such as titanium, it is possible to prevent the end of the unused cutting edge from being damaged by the generated chips, When it is formed in a square plate shape, all cutting edges can be used evenly and effectively. Further, since the chips do not interfere with the first end portion of the adjacent cutting blade and are strongly pressed, the stress applied to the chips can be reduced and smooth discharge can be promoted.

  Here, if a chamfered corner portion is formed between adjacent edge portions of the at least one polygonal surface in the cutting insert, and the step portion is formed in the corner portion, the entire length of the edge portion is increased. As a result, it is possible to form a cutting edge, to ensure a long cutting edge length for each cutting insert, and to reduce the number of cutting inserts required for one cutting edge exchangeable cutting tool . In particular, in this case, the bisector of the angle formed by the adjacent side ridge portion of the polygonal surface when viewed from the direction facing the rake face from the second end portion of the other cutting edge. And the intersection with the corner portion, the stepped portion is formed so as to have the lowest concave portion so that a large pocket can be secured from the lowest portion on the rake face connected to the cutting edge. Further, it is possible to further improve the chip discharging property.

  As described above, according to the present invention, it is possible to use an effective cutting edge without causing damage to an unused cutting edge of the cutting insert, and to improve the chip discharging performance, thereby efficiently performing the cutting process. Can be performed.

It is a perspective view which shows one Embodiment of the cutting insert of this invention. It is a top view of embodiment shown in FIG. It is a side view of the arrow X direction view in FIG. It is a side view of the arrow Y direction view in FIG. It is an enlarged side view of A part in FIG. It is a bottom view of embodiment shown in FIG. It is a perspective view which shows one Embodiment of the blade-tip-exchange-type cutting tool of this invention which attached the cutting insert of embodiment shown in FIG. FIG. 8 is a side view of the embodiment shown in FIG. 7. FIG. 8 is a bottom view of the embodiment shown in FIG. 7.

  FIGS. 1 to 6 show an embodiment of the cutting insert of the present invention, and FIGS. 7 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. Is. The blade-tip-exchangeable cutting tool of the present embodiment has an external cylindrical tool body 11 centering on the axis O that is rotated in the tool rotation direction T around the axis O, and the tool body 11 has a distal end outer peripheral portion. A plurality of chip discharge grooves 12 are formed at intervals in the circumferential direction, and the cutting insert of this embodiment is attached to and detached from the insert mounting seat 13 formed on the wall surface of the chip discharge grooves 12 facing the tool rotation direction T. This is a tip-changeable turning tool (end mill) that can be attached.

  The cutting insert includes a polygonal plate-like insert body 1 formed of a hard material such as a cemented carbide, and the insert body 1 has a substantially square plate shape in this embodiment, that is, two squares. It has a surface and four side surfaces arranged around it. At the center of the two square surfaces, a mounting hole 2 having a circular cross section passing through the insert body 1 in the plate thickness direction is opened. The insert body 1 is related to the insert center line C passing through the center of the mounting hole 2. The shape is 90 ° rotationally symmetric, that is, when the insert body 1 is rotated by 90 ° around the insert center line C, the outer shape overlaps with the insert body 1 in the original position.

  Cutting edges 4 each having a rake face 3 on one square surface are formed on four side ridges of one square surface of the insert body 1. Further, a chamfered corner portion is formed between adjacent side ridge portions of this one square surface. Further, the other square surface opposite to the one square surface is a seating surface 5 to the insert mounting seat 13, and the seating surface 5 is a flat surface perpendicular to the insert center line C. ing.

  Furthermore, the four side surfaces of the insert body 1 are flank surfaces 6 of the respective cutting blades 4, and these flank surfaces 6 are directed toward the inside of the insert body 1 at equal inclination angles toward the seating surface 5 side. So as to be inclined. That is, the cutting insert of this embodiment is a positive type cutting insert. The mounting hole 2 is formed to have a constant inner diameter after being reduced in diameter toward the seating surface 5 side.

  Each of the cutting edges 4 has a second end 4B opposite to the first end 4A from the first end 4A of the cutting edge 4 in one circumferential direction of the one square surface. It is inclined to gradually rise as it goes to. That is, the individual cutting blades 4 are arranged such that the distance from the seating surface 5 in the direction of the insert center line C gradually increases as the distance from the first end 4A to the second end 4B increases, or the insert center line C It is formed so as to protrude in the direction, and is inclined so as to protrude toward the side on which the one square surface faces.

  In the present embodiment, as shown in FIG. 2, the clockwise direction around the insert center line C in the plan view facing the one square surface is the one circumferential direction, and one cutting edge 4 The end portion on the clockwise direction side is the first end portion 4A, and the opposite end portion on the counterclockwise direction side is the second end portion 4B. Accordingly, the first and second end portions 4A and 4B of the cutting blades 4 are alternately arranged in the counterclockwise direction.

  Here, in the present embodiment, the cutting edge 4 is formed so as to gradually rise with a constant inclination from the first end portion 4A toward the second end portion 4B. Therefore, the cutting edge 4 has a first end portion 4A that is most recessed in the direction of the insert center line C and a second end portion 4B that protrudes most in the direction of the insert center line C. As shown in FIG. 2, it extends linearly, and the inclination angle with respect to a plane perpendicular to the insert center line C is, for example, in the range of 1 ° to 5 °. Furthermore, the cutting edge 4 also extends linearly between the first end 4A and the second end 4B as shown in FIG. 2 in the plan view.

  Further, the cutting edges 4 formed on the adjacent side ridges of one square surface include the first end 4A of one cutting edge 4 and the second end 4B of the other cutting edge 4. Are opposed to each other via a stepped portion 7 that is recessed from the second end portion 4B formed in the corner portion toward the first end portion 4A. In other words, in the present embodiment, the first and second end portions 4A and 4B of the cutting blade 4 having a linear shape as described above serve as a boundary between a side ridge portion and a corner portion of one square surface, and this corner portion is The stepped portion 7 is recessed toward the seating surface 5 as it goes from the second end 4B of the other cutting blade 4 facing the corner portion to the first end 4A of the one cutting blade 4. Or so as to recede in the direction of the insert center line C.

  Here, in the present embodiment, each corner portion of the one square surface has a crossed ridge line portion between adjacent flank surfaces 6 formed in a substantially 1/4 cylindrical surface shape, so that FIG. As shown in FIG. 1, the chamfer is chamfered in a ¼ arc shape in contact with the adjacent linear cutting edge 4. And the level | step-difference part 7 of this embodiment is the angle which the two side ridge parts which the said one square surface (polygonal surface) which the said rake face 3 makes when seeing from the direction which opposes the rake face 3 makes | forms. As seen in the bisector L direction (viewed in the direction of the arrow Y in FIG. 2), as shown in FIGS. 4 and 5, the convex portion that contacts the other cutting edge 4 from the second end 4B of the other cutting edge 4 It is formed so as to be indented while drawing a curve, and then further indented while drawing a concave curve in contact with this convex curve so as to contact one of the cutting edges 4 at the first end 4A.

  Further, in the present embodiment, the stepped portion 7 that is recessed from the second end 4B of the other cutting edge 4 toward the first end 4A of the one cutting edge 4 in the corner portion is thus formed in the one peripheral edge. In the rotating direction, the lowest concave portion 7A as shown in FIG. 5 is formed between the second end 4B of the other cutting edge 4 and the intersection P between the bisector L and the corner. Have. Here, in the present embodiment, in detail, in the side view shown in FIG. 5, the stepped portion 7 that is recessed while drawing a convex curve from the second end 4B of the other cutting edge 4 draws a concave curve as described above. However, the most recessed point of the further recessed portion is the lowest portion 7A, and in particular coincides with the intersection point P. After the stepped portion 7 draws a slight concave curve, As viewed, it bulges in a straight line shape in contact with the concave curve, and continues to the first end 4A of one of the cutting edges 4.

  The rake face 3 is formed from each cutting edge 4 except for a diagonal portion (the bisector L in the present embodiment) of the one square face from each corner portion to the insert center line C in the plan view. The first rake face 3A that moves toward the seating surface 5 with a gentle and substantially constant inclination toward the inside of the insert body 1 vertically, that is, recedes in the direction of the insert center line C, and protrudes inside the first rake face 3A. There is provided a second rake face 3C that is smoothly connected via the curved surface 3B and that faces the seating face 5 side with a substantially constant slope that is steeper than the first rake face 3A. In addition, the periphery of the opening of the one square surface mounting hole 2 is a flat surface perpendicular to the insert center line C.

  Further, the first rake face 3A is inclined in the direction along the cutting edge 4 so as to gradually rise from the first end 4A toward the second end 4B in the same manner as the cutting edge 4. Yes. The widths of the first and second rake surfaces 3A and 3C in the plan view are substantially constant along the cutting edge 4, and the width of the convex curved surface 3B is from the first end 4A to the second end. It is formed to become slightly wider as it goes to 4B.

  On the other hand, in the diagonal line portion, the one square surface is inclined so as to be directed toward the seating surface 5 as it goes toward the insert center line C as in the case of the rake face 3, and a portion continuous with the first rake face 3A is provided. Like the stepped portion 7, the second cutting edge 4 is recessed while drawing a concave curved surface in contact with the convex curved surface after being concaved while drawing a convex curved surface from the first rake face 3A on the second end 4B side, The first cutting edge 4 is formed so as to be in contact with the first rake face 3A on the first end 4A side. Further, the portion connected to the convex curved surface 3B is concaved from the second end portion 4B side of the other cutting edge 4 while the width in the plan view is narrowed, and the first end portion 4A side of the one cutting edge 4 is reduced. It is formed so that it may continue.

  In the cutting edge-exchangeable cutting tool of this embodiment to which such a cutting insert is attached, the rear end portion (the upper right portion in FIG. 7 and the upper portion in FIG. 8) of the tool main body 11 is attached to the spindle of the machine tool. As described above, while being rotated in the tool rotation direction T around the axis O, the workpiece is usually fed in a direction perpendicular to the axis O to perform shoulder machining or groove cutting on the work material. That is, the side attached to the spindle of the machine tool in this way is the rear end side of the tool main body 11, and the opposite side is the front end side of the tool main body 11.

  In the present embodiment, the four chip discharge grooves 12 are formed at equal intervals in the circumferential direction on the outer periphery of the tip of the tool body 11, and the tool rotation direction T increases from the tip of the tool body 11 toward the rear end side in the axis O direction. It is formed to be twisted toward the opposite side. Five insert mounting seats 13 to which the cutting inserts of the above-described embodiment are attached are respectively provided on the wall surfaces of the chip discharge grooves 12 facing the tool rotation direction T. Is formed in a spiral staircase shape that is twisted with a gap larger than the thickness of the insert body 1 in the direction of the insert center line C toward the opposite side.

  However, these insert mounting seats 13 are formed from a position spaced from the front end of the tool body 11 to the rear end side in the axis O direction, and are the most advanced on the wall surface of each chip discharge groove 12 facing the tool rotation direction T. An insert mounting seat 14 to which a cutting insert for a tip having a shape different from that of the cutting insert of the above embodiment is attached is formed. The insert mounting seat 14 of the tip insert is formed on the tool rotation direction T side with an interval from the insert mounting seat 13 that is continuous in a spiral staircase shape.

  The cutting insert for the tip attached to the insert mounting seat 14 is a positive type cutting insert including an insert body 21 which is also formed of a hard material such as cemented carbide and has a substantially parallelogram plate shape. Two L-shaped cutting edges 23 having the one parallelogram surface as the rake face 22 are formed on approximately half and the long side of the short side intersecting the acute angle portion of the two parallelogram surfaces. ing. On the rake face 22, the side ridge portion where the cutting edge 23 is formed is formed so that the thickness between the insert face 21 and the seating surface 24 is one step thicker. Further, a mounting hole 25 penetrating the insert main body 21 is also opened at the center portion of the rake face 22 and the seating face 24 of the tip insert.

  The most advanced insert mounting seat 14 of the tool main body 11 to which such a cutting insert for a tip is attached opens on the outer peripheral side of the tip of the tool main body 11, and a bottom surface 14 </ b> A facing the tool rotation direction T, and the tool main body 11. A wall surface 14B facing the outer peripheral side and a wall surface 14C facing the distal end side are provided. A screw hole (not shown) into which the clamp screw 26 inserted into the mounting hole 25 is screwed is formed on the bottom surface 14A.

  The insert for the tip of the insert mounting seat 14 has the seating surface 24 of the insert main body 21 in close contact with the bottom surface 14A, and the long side surface connected to one cutting edge 23 is the wall surface 14B and the short side surface is the wall surface 14C. It is made to contact | abut and it attaches to the insert attachment seat 14 so that attachment or detachment is possible by screwing in the clamp screw 26. The tip insert thus attached causes the long side portion of the other cutting blade 23 to protrude toward the outer peripheral side of the tool body 11 and causes the short side portion to protrude toward the tip side of the tool body 11. It arrange | positions so that the rotation locus | trajectory around the axis line O of the other one cutting blade 23 of the inserts for tips of the strip chip discharge groove 12 may correspond substantially.

  On the other hand, the insert mounting seat 13 to which the cutting insert of the above embodiment is mounted includes a bottom surface 13A facing the tool rotation direction T, a wall surface 13B facing the outer peripheral side of the tool body 11, and a wall surface facing the rear end side of the tool body 11. 13C. A screw hole is formed in the bottom surface 13A, and the cutting insert of the above embodiment has the seating surface 5 of the insert body 1 in close contact with the bottom surface 13A and one flank 6 on the inner peripheral side of the tool body 11. The other flank 6 is brought into contact with the wall surface 13B toward the tip side of the tool body 11 and the clamp screw 26 inserted through the mounting hole 2 is screwed into the screw hole. Is attached to the insert mounting seat 13 in a detachable manner.

  In the cutting insert according to the embodiment thus mounted on the insert mounting seat 13, one square surface formed with the rake face 3 of the insert body 1 is directed in the tool rotation direction T, and the one flank 6 The cutting edge 4 formed on the flank 6 directed toward the outer peripheral side of the opposite tool body 11 is projected to the outer peripheral side of the tool body 11 and used for cutting. Therefore, the first end 4A of the cutting edge 4 used for this cutting is directed to the front end side of the tool body 11, and the second end 4B is directed to the rear end side of the tool body 11, and the cutting edge 4 is used. The blade 4 is inclined so as to protrude in the direction of the insert center line C and gradually rise as it goes from the front end side to the rear end side of the tool body 11.

  However, the bottom surfaces 13A and 14A of the insert mounting seats 13 and 14 are both slightly inclined toward the opposite side of the tool rotation direction T toward the rear end side of the tool body 11, and in particular the insert mounting seat 13 The inclination angle of the bottom surface 13A with respect to the axis O is larger than the inclination angle with respect to a plane perpendicular to the insert center line C of the cutting blade 4. Therefore, when attached to the tool body 11, the cutting blades 4 and 23 protruded toward the outer peripheral side of the tool body 11 are directed toward the opposite side of the tool rotation direction T toward the rear end side of the tool body 11. Will be given a positive axial rake angle. In other words, the cutting edge-exchangeable cutting tool (end mill) of the present embodiment is a right-handed, right-handed, end-clockwise end mill.

  Further, in the cutting insert attached to the insert mounting seats 13 and 14 of one chip discharge groove 12, the cutting blades 4 and 23 projected to the outer peripheral side of the tool body 11 are one cylinder centered on the axis O. It is generally located on the surface. However, since the cutting edge 4 is in a straight line inclined with respect to the axis O as described above, it is not positioned exactly on one cylindrical surface. And on this one cylindrical surface, the cutting edges 4 and 23 are arrange | positioned so that the rotation locus | trajectory around the axis line O may continue or may overlap.

  That is, in the cutting insert of the above-described embodiment mounted on the five insert mounting seats 13, the tool body 11 rear end side with respect to the second end 4B of the cutting insert 4 of the cutting insert on the tool body 11 tip side. 4A of the cutting blade 4 of the cutting insert adjacent to is arrange | positioned so that it may be located in the same position or a little front end side in the axis line O direction. Further, the cutting insert adjacent to the rear end side of the tool body 11 is also provided to the rear end portion of the cutting blade 23 projected to the outer peripheral side of the tool body 11 of the cutting insert attached to the most advanced insert mounting seat 14. The first end 4A of the cutting edge 4 is arranged in the same manner.

  Furthermore, in the cutting inserts attached to the insert mounting seats 13 and 14 of the plural (four) chip discharge grooves 12, the above-mentioned cylinders in which the cutting blades 4 and 23 protruded to the outer peripheral side of the tool body 11 are located. It arrange | positions so that a surface may correspond. However, the positions of the first and second end portions 4A and 4B in the axis O direction are shifted from each other between the cutting inserts attached to the insert mounting seat 13 of the chip discharge groove 12 adjacent in the circumferential direction.

  For example, in this embodiment in which the four chip discharge grooves 12 are formed, the first cutting edge 4 of the cutting insert attached to the insert mounting seat 13 of every other two chip discharge grooves 12 in the circumferential direction. The positions of the second end portions 4A and 4B in the direction of the axis O are arranged at the substantially central portion in the direction of the axis O of the cutting blade 4 of the cutting insert attached to the insert mounting seat 13 of the remaining two chip discharge grooves 12. It is installed.

  In the cutting insert and the cutting edge exchangeable cutting tool configured as described above, the cutting blade 4 projected to the outer peripheral side of the tool body 11 of the cutting insert attached to the insert mounting seat 13 is a positive axial rake as described above. Since the angle is given, it is cut into the work material from the first end portion 4A located on the tool rotation direction T side and directed toward the tip end side of the tool main body 11 to generate chips. The generated chips are rounded into a string shape while rubbing the rake face 3, and the second end 4 </ b> B facing the rear end side of the tool body 11 located on the side opposite to the tool rotation direction T is cut. It is separated from the rake face 3 away from the material and discharged through the chip discharge groove 12.

  At this time, in the cutting insert having the above configuration, the cutting blade 4 is inclined with respect to the insert body 1 so as to gradually rise from the first end portion 4A toward the second end portion 4B. The rake face 3 is rubbed so as to be pushed up along the inclination of the cutting edge 4. And in the 2nd edge part 4B side from which a chip | tip separates, the 1st of the other cutting blade 4 located in the tool body 11 rear end side adjacent via the corner with respect to the cutting edge 4 used for cutting. 4A is arranged so as to be recessed with respect to the second end 4B via the stepped portion 7, so that when the chips leave, the first end 4A of the other cutting blade 4 Interference and strong pressing can be avoided.

  Further, the first end 4A of the cutting edge 4 is positioned in one circumferential direction (clockwise direction in the present embodiment) of the square surface, and the second end 4B is positioned opposite thereto. Therefore, even if the insert body 1 is rotated by 90 ° around the insert center line C by 90 ° in this embodiment and reattached to the insert mounting seat 13, the cutting edge protrudes to the outer peripheral side of the tool body 11 and is used for cutting. 4 is inclined so as to gradually rise from the first end 4A toward the second end 4B, and the first of the other cutting blades 4 positioned on the rear end side of the tool body 11 as described above. The chips do not interfere with the end 4A of the.

  Therefore, according to the cutting insert having the above-described configuration and the cutting edge-exchangeable cutting tool to which the cutting insert is attached as described above, a regular polygon in which the insert body 1 is rotationally symmetrical by a predetermined angle, particularly as in the present embodiment. Even if the work material is a difficult-to-cut material such as titanium when the cutting edge 4 is formed on all the side ridges of the at least one regular polygonal surface in the form of a plate, It is possible to prevent the other cutting blades 4 from being damaged by the chips generated by the cutting blades 4 used for cutting. For this reason, it is possible to prevent unused cutting blades 4 from becoming unusable due to damage, and to use all cutting blades 4 formed in the insert body 1 evenly and effectively.

  Further, as described above, it is possible to avoid that the chips are strongly pressed against the first end 4A of the other cutting edge 4, and as a result, unnecessary stress acts on the chips and the separation of the chips deteriorates. It can also prevent the situation from occurring. Therefore, according to the cutting insert and the cutting edge-exchangeable cutting tool having the above-described configuration, it is possible to promote the improvement of chip dischargeability, and it is possible to achieve efficient cutting.

  Further, in the cutting insert of the present embodiment, the cutting edge 4 is linear in plan view, and the corner portion of one square surface is chamfered in a quarter arc shape, that is, the boundary, that is, the cutting edge 4. The first and second end portions 4A and 4B are contact points between the first and second corner portions. And since the said level | step-difference part 7 is formed in the corner part chamfered in this way, long cutting edge length can be ensured to the cutting edge 4 which makes | forms linear form.

  For this reason, for example, in the cutting insert attached to the insert mounting seat 13 of one chip discharge groove 12 as described above, the second end 4B of the cutting blade 4 of the cutting insert on the tip side of the tool body 11 and the tool body 11 The cutting edge that is used for cutting with a small number of cutting inserts by disposing the first end 4A of the cutting edge 4 of the cutting insert adjacent to the rear end side at the same position in the direction of the axis O. The rotation trajectory around the four axis O can be continued long in the direction of the axis O. That is, since the number of cutting inserts required for one tool body 11 can be reduced, according to the present embodiment, more efficient and economical cutting can be performed.

  On the other hand, as in the present embodiment, in the chip discharge grooves 12 adjacent to each other in the circumferential direction of the tool main body 11, between the cutting inserts attached to the insert attachment seat 13, first and second in the axis O direction. By shifting the positions of the end portions 4A and 4B from each other, there is an interval between the first and second end portions 4A and 4B between the adjacent cutting inserts of the one chip discharge groove 12, so that the processing surface is formed. Even if uncut residue occurs, the uncut residue can be removed by the cutting blade 4 of the cutting insert located on the opposite side of the tool rotation direction T, and a high-quality processed surface can be formed.

  Furthermore, in the present embodiment, the stepped portion 7 formed in the corner portion in this way is from the direction facing the rake face 3 in the one circumferential direction from the second end portion 4B of the other cutting edge 4. When viewed from the direction of the bisector L of the angle formed by two adjacent side ridges of the one square surface (polygonal surface), that is, the direction facing the rake face 3, the two side ridges are extended. It is formed so as to have the lowest concave portion 7A between a straight line that bisects the angle formed by the two side ridges at the intersection of the lines and the intersection P with the corner. For this reason, in the rake face 3 connected to the cutting edge 4, it is possible to secure a large pocket that does not hinder the discharge of chips even from the lowest part 7A to the first end 4A. It is possible to improve the performance and to promote more efficient cutting.

  However, in one chip discharge groove 12, a side ridge portion where the cutting blade 4 of the cutting insert on the tip side of the tool body 11 is formed and a cutting blade 4 of the cutting insert adjacent to the rear end side of the tool body 11 are formed. In the case where the side ridges are overlapped with each other in the rotation trajectory around the axis O, the stepped portion 7 may be formed beyond the corner portion to the side ridge portion. Further, in the present embodiment, the corner portion is formed in an arc shape, but the intersecting ridge line portion of the adjacent flank 6 may be chamfered by a plane intersecting the flank 6 to form a chamfer-shaped corner portion. .

  In the present embodiment, the lowest portion 7A of the stepped portion 7 is the most recessed point in the portion where the stepped portion 7 forms a concave curve in the side view. It extends toward the first end 4A side at a certain level along a plane perpendicular to the insert center line C from the recessed point and intersects the first end 4A, or the first end 4A. It may be raised from the front of the first end 4A and may be continuous with the first end 4A. Even in such a case, if the lowest recessed portion 7A of the stepped portion 7 is partially located in the region between the second end 4B of the other cutting edge 4 and the intersection P, As described above, a large pocket can be secured.

  Further, in the present embodiment, the insert body 1 is formed in a substantially square plate shape, but may be another regular polygonal plate shape such as a substantially equilateral triangular plate shape. The present invention may be applied to a cutting insert that is attached to the tool body so as to selectively use cutting edges formed on the long side ridge portion and the short side ridge portion of the at least one rectangular surface. Moreover, although the cutting insert of this embodiment is a positive type, you may apply this invention to the negative type cutting insert in which a flank extends in parallel with the insert centerline C, and in this case, two polygonal surfaces Cutting edges may be formed on both side ridges.

  Furthermore, in this embodiment, the cutting edge 4 is formed in a linear shape that gradually rises with a certain inclination as it goes from the first end 4A to the second end 4B. Alternatively, it may be formed as a convex curve or a concave curve, or a combination of a curve and a straight line. In this case, the inclination angle of the cutting edge 4 with respect to the plane perpendicular to the insert center line C is within the range of 1 ° to 5 ° as the inclination angle of the straight line connecting the first and second end portions 4A and 4B. Good. In addition, when the cutting blade 4 is formed in a curved shape in this way, it becomes possible to position the cutting blade 4 in a state where it is attached to a cutting edge exchangeable cutting tool (end mill) on one cylindrical surface. A high-quality processed surface can be formed.

  Further, the cutting edge exchangeable cutting tool of the present embodiment is a right edge, right-twisted, clockwise edge-changing end mill, but the left edge, opposite to this, left-handed, counterclockwise edge-changing cutting tool ( The present invention may be applied to a turning tool. In this case, the cutting insert has a mirror-symmetric shape with respect to the cutting insert of the above-described embodiment, and one circumferential direction of the polygonal surface on which the rake face is formed is in a plan view facing the polygonal surface. The direction is counterclockwise about the insert center line C.

DESCRIPTION OF SYMBOLS 1 Insert body 2 Mounting hole 3 Rake face 4 Cutting edge 4A 1st edge part 4B of cutting edge 4 2nd edge part of cutting edge 4 5 Seating surface 6 Relief surface 7 Step part 7A Minimum part of step part 11 Tool Main body 12 Chip discharge groove 13, 14 Insert mounting seat C Insert center line O Tool axis 11 axis T Tool rotation direction L Adjacent sides of the polygonal surface (one square surface) when viewed from the direction facing the rake face 3 The bisector of the angle formed by the ridges P The intersection of the bisector L and the corner

Claims (4)

A polygonal plate-like insert body is provided, and each edge of the at least one polygonal surface of the insert body is formed with a cutting edge having a rake face on the polygonal surface, respectively.
The cutting edges gradually protrude from the first end of the cutting edge in one circumferential direction of the polygonal surface toward the second end opposite to the first end. As well as
The cutting edges formed on adjacent side ridges of the polygonal surface are such that the first end of one cutting edge and the second end of the other cutting edge are the other cutting edge. A cutting insert characterized by facing each other through a stepped portion that is recessed from the second end of the blade toward the first end of the one cutting blade.   2. The cutting insert according to claim 1, wherein a chamfered corner portion is formed between adjacent side ridge portions of the polygonal surface, and the step portion is formed in the corner portion. .   The intersection of the bisector of the angle formed by the adjacent edge of the polygonal surface when viewed from the second edge of the other cutting edge in the direction facing the rake face and the corner part The cutting insert according to claim 2, wherein the step portion has a lowest concave portion. A cutting edge exchangeable cutting tool in which the cutting insert according to any one of claims 1 to 3 is detachably attached to the outer periphery of a tip end of a tool body rotated around an axis,
In the cutting insert, one cutting edge is projected to the outer peripheral side of the tool body to give a positive axial rake angle, and the first end of the cutting edge is located on the tip side of the tool body. A cutting edge-exchangeable cutting tool, wherein the cutting tool is directed and the second end portion is directed to the rear end side of the tool body.

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