JP5594213B2 - Cutting insert - Google Patents

Description

  In the present invention, a laminar sintered body obtained by laminating a superhard sintered body such as CBN (cubic boron nitride) and a cemented carbide layered on the rake face of the insert body is raked. The present invention relates to a cutting insert which is disposed so as to be positioned at a corner portion of a surface, and is attached to, for example, a blade-tip-exchangeable front milling cutter to constitute the cutting blade.

  As described above, as a cutting insert in which an ultra-high hardness sintered body such as CBN is disposed at the corner portion of the rake face of the insert body, for example, a cutting insert described in Patent Document 1 is known. It has been. In the cutting insert described in Patent Document 1, the cutting edge with chamfer honing is formed on the ultra-high hardness sintered body thus arranged in the corner portion, and the honing angle is the tip of the corner portion. It is made larger than the position separated from the tip, and damage to the cutting edge at the corner tip can be prevented even at high feed processing, while the cutting blade located at a position away from the tip is used as a wiper blade. It is said that it is possible to reduce the cutting force in the radial direction and improve the finished surface accuracy and substantially improve the tool life.

International Publication No. 2006/091141 Pamphlet

  By the way, in the conventional cutting insert in which the ultra-high hardness sintered body is disposed in the corner portion as described above, as described in Patent Document 1, the cutting blade used for cutting is the ultra-high hardness sintered body. It is only the part formed in the. However, although such an ultra-high hardness sintered body has extremely high hardness, it also has high brittleness. For example, when used in a rolling process for intermittent cutting, the secondary cutting edge acts as the wiper blade. Chipping and chipping are likely to occur at the end opposite to the corner. In particular, as described in the above-mentioned Patent Document 1, in a cutting insert in which the honing angle of chamfer honing applied to the cutting blade at a position separated from the corner tip used as the wiper blade is reduced, this wiper blade Since the cutting edge strength is reduced, chipping and chipping become more prominent.

  The present invention has been made under such a background. As described above, a cutting insert in which a highly brittle ultra-high hardness sintered body is disposed in a corner portion of a rake face is used for a rolling process. However, an object of the present invention is to provide a cutting insert that can prevent chipping and chipping from occurring on the cutting edge.

  In order to solve the above problems and achieve such an object, the present invention provides a laminar sintered body obtained by laminating an ultra-high hardness sintered body and a cemented carbide alloy in layers on the rake face of the insert body. The ultra-high-hardness sintered body is disposed at the corner portion of the rake face so as to face the rake face side, and the corner is formed on the side ridge portion of the rake face on the layered sintered body. A cutting blade extending from the corner is formed, and the cutting blade is formed with a honing surface in which the honing angle gradually increases as the distance from the corner portion increases, and the ultrahigh hardness in the layered sintered body A boundary surface between the sintered body and the cemented carbide is crossed with a honing surface of the cutting blade.

  In the cutting insert configured as described above, a laminar sintered body of an ultrahigh hardness sintered body such as CBN and a cemented carbide alloy is disposed on the rake face of the insert body, and among these, the ultrahigh hardness sintered body Is positioned at the corner portion of the rake face and directed toward the rake face side, and a honing blade is formed on the layered sintered body. Here, the honing surface by this honing is designed so that the honing angle gradually increases as the distance from the corner portion increases, so that the cutting blade strength is ensured even when the cutting blade extending from this corner portion is used as a wiper blade. be able to.

  The boundary surface between the super-hard sintered body of the layered sintered body and the cemented carbide is intersected with the honing surface of the cutting edge, so that the honing surface of the cutting edge on the corner side is super high. The honing surface of the cutting blade on the opposite side to the corner portion is formed on the cemented carbide, whereas it is formed on the hardness sintered body. However, such a cemented carbide has a low hardness but sufficient hardness for cutting, while it has a high toughness compared to a super-hard sintered body such as CBN. Even in intermittent cutting, it is possible to prevent chipping and chipping from occurring on the cutting blade on the side opposite to the corner portion in combination with ensuring the cutting blade strength as described above.

  Here, when the cutting edge extending from the corner portion is used as the wiper blade as described above, the intersecting ridge line between the honing surface of the cutting edge substantially involved in cutting and the flank surface formed in the layered sintered body. When viewed from the direction facing the rake face, it is desirable to form a convex curve having a larger radius of curvature than the corner portion, which once protrudes as it moves away from the corner portion, then retreats after passing through the protruding end portion. That is, by making the intersecting ridge line into such a convex curve shape having a large curvature radius, the finished surface of the work material has a cross-sectional shape in which a concave curve having a large curvature radius is continuous, so that the cutting edge is inclined. Even if there is, it is possible to prevent the feed mark from being left on the finished surface.

  Further, when the intersection ridge line is a convex curve having a large radius of curvature that retreats from the corner portion through the tip when viewed from the direction facing the rake face, the intersection ridge line is a rake face. When viewed from the direction facing the flank along the flank, it is retracted so as to gradually move away from the rake face toward the opposite side of the corner from the tip, but the layered sintered body from the tip It is desirable that the amount of retreat of the intersecting ridge line up to the end of the cutting edge on the opposite side to the corner in the range from 0.005 mm to 0.02 mm.

  That is, the above-mentioned intersection ridgeline is retreated so as to gradually move away from the rake face as it goes from the tip when viewed from the rake face to the opposite side of the corner part, thereby flank along the rake face. The width of the honing surface when viewed from the direction opposite to the corner gradually increases from the tip toward the opposite side of the corner, so the chipping and chipping of the cutting edge can be prevented more reliably on the opposite side of the corner. Can do.

  However, if the amount of retraction is too large, the cutting edge will be too far away from the finished surface on the side opposite to the corner due to the clearance angle being given to the flank during machining, resulting in deterioration of the finished surface roughness or finishing. There is a risk of causing undulations on the surface, and if the retraction amount is too small to be as small as 0 mm, the above effect may not be obtained. Therefore, the retraction amount between the protruding end and the edge of the cutting edge opposite to the corner portion As described above, the difference is desirably 0.005 mm or more and 0.02 mm or less.

  If the honing surface is formed so that the width in the direction along the rake surface gradually increases as the distance from the corner portion increases, the edge strength on the opposite side of the corner portion is also improved, It is possible to reliably prevent chipping and chipping.

  As described above, according to the present invention, even in a cutting insert in which an ultra-high hardness sintered body that is both hard and highly brittle is disposed in a corner portion of a rake face, Chipping and chipping of the cutting edge can be prevented, and stable cutting can be performed over a long period of time even when the cutting edge is used as a wiper blade in intermittent cutting such as rolling.

It is a top view which shows one Embodiment of the cutting insert of this invention. It is a side view of the arrow X direction view of embodiment shown in FIG. It is a side view of the arrow line Y direction view of embodiment shown in FIG. It is a side view of the arrow Z direction view of embodiment shown in FIG. FIG. 2 is an enlarged plan view around a corner portion C of the embodiment shown in FIG. 1. It is an enlarged side view of the cutting blade part in FIG. It is a partially broken side view of the blade-tip-exchange-type front milling machine to which the embodiment shown in FIG. 1 is attached. It is a bottom view of the front milling machine shown in FIG. FIG. 8 is an enlarged side view of the front milling machine shown in FIG.

  FIGS. 1 to 6 show an embodiment of the cutting insert of the present invention, and FIGS. 7 to 9 show a face mill that is a cutting edge exchangeable cutting tool to which the cutting insert of this embodiment is attached. It is. In the cutting insert of this embodiment, the base body 1A of the insert body 1 is made of cemented carbide, and as shown in FIG. 1, one acute angle portion of a polygon, specifically a substantially parallelogram, becomes a right angle. A pair of flat plate surfaces having a polygonal shape (pentagonal shape) facing in the thickness direction of the insert body 1 (vertical direction in FIGS. 2 to 4). And five side surfaces arranged around the periphery.

  One of the pair of flat plate surfaces of the base body 1A of the insert body 1 (the upper flat plate surface in FIGS. 2 to 4) has one polygonal corner portion C (the right angle described above) formed by the flat plate surface. A rake face 2 is formed in a region including a corner portion cut out so that the right corner portion in FIG. 1 is included, and the other flat plate surface opposite to the one flat plate surface (FIG. 2 to FIG. 2). The lower flat plate surface in FIG. 4 is a seating surface 3 on the insert mounting seat formed on the tool body of the cutting edge exchangeable cutting tool.

  Of the five side surfaces of the insert body 1, two side surfaces connected to the corner portion C are flank surfaces 4, and gradually recede from the rake surface 2 toward the seating surface 3 side toward the inside of the insert body 1. Thus, the cutting insert of this embodiment is made a positive insert. Further, the three side surfaces (the upper side, the lower side, and the left side surface in FIG. 1) of the insert main body 1 excluding the side surface as the flank 4 extend along the thickness direction. The side surfaces connected to the side surfaces are parallel to each other, and the remaining one side surface is formed obliquely so as to intersect one of the parallel side surfaces with an acute angle and the other with an obtuse angle.

  Furthermore, a concave portion 5 is formed in the corner portion C of one flat plate surface on which the rake face 2 is formed so as to cut out the base body 1A of the insert body 1. The concave portion 5 is formed in an L shape as shown in FIGS. 2 and 3 on one side surface (the upper side surface of the one corner portion C in FIG. 1) of the two side surfaces to be the flank 4. While opening, on the other side surface (the lower side surface of the one corner C in FIG. 1), as shown in FIGS. 3, 4 and 6, the bottom surface 5A of the recess 5 is the one side surface. And a wall surface 5B extending in the thickness direction so as to intersect with the bottom surface 5A and facing the front end side of the corner portion C. ing.

  And in this recessed part 5, the layered sintered body 6 which integrally sintered the super-hard sintered body (CBN in this embodiment) 6A and cemented carbide 6B which consist of CBN or a diamond sintered body in layer form, Among them, the ultra-high hardness sintered body 6A portion is disposed at the corner portion C so as to face the rake face 2 side. That is, this layered sintered body 6 is obtained by integrally compacting and sintering the raw powder of the ultra-high hardness sintered body 6A and the raw powder of the cemented carbide 6B, and sintering into a thin plate shape. The material is cut into a predetermined shape by electric discharge machining or the like, and is joined and fixed to the recess 5 by brazing or the like.

  Here, the layered sintered body 6 in the present embodiment has an ultrahigh hardness sintered body 6A and an ultrahigh sintered body 6A as shown in FIG. Each of the hard alloys 6B has a certain thickness. Further, as the bottom surface 5A of the recess 5 is inclined along the other side surface which is also the flank 4 from this one side surface, the ultra-high hardness sintered body 6A portion becomes gradually thinner as it cuts toward the one flat plate surface side. In the middle, the thickness of the cemented carbide 6B portion becomes a constant thickness until the thickness of the ultra-hard sintered body 6A portion becomes zero, and then the thickness gradually decreases. It is formed so as to be interrupted before reaching zero. Therefore, the recess 5 is left between the end portion of the cemented carbide 6B portion and the base body 1A of the insert main body 1.

  Further, the layered sintered body 6 has a surface facing the rake face 2 side that is flush with the one flat plate surface of the base body 1A of the insert body 1 connected to the surface, and is perpendicular to the thickness direction. In addition, the surface connected to the two side surfaces of the base body 1A as the flank 4 is flush with these two side surfaces, and gradually recedes toward the seating surface 3 as with the two side surfaces. It is inclined like so. Note that, on the side opposite to the corner portion C of the one flat plate surface of the base body 1A, an inclined plane 1B that inclines toward the seating surface 3 side from one side to the other of the parallel side surfaces of the base body 1A. Is formed.

  A cutting edge 7 extending from the corner portion C is formed at a cross ridge line portion between the surface facing the rake face 2 side of the layered sintered body 6 and the surface continuous with the two side surfaces as the flank face 4 of the base 1A. In other words, these surfaces are used as the rake face 2 and the flank face 4 of the cutting edge 7, and the cutting edge 7 is formed on the edge of the rake face 2 on the layered sintered body 6. It will be. Further, the corner portion C is chamfered in a cylindrical surface from the intersecting ridge line portion of the two side surfaces of the base 1A to the layered sintered body 6, whereby the corner portion C of the cutting edge 7 is chamfered. A corner blade 7A having a substantially ¼ arc shape is formed.

  Further, honing is applied to the cutting edge 7, and a honing surface 8 is formed so as to intersect the rake face 2 and the flank face 4. Here, the honing in the present embodiment is a chamfer honing, and the honing surface 8 forms a straight line in a cross section perpendicular to the cutting edge 7 and intersects the rake surface 2 at an obtuse angle, while the honing surface 8 and the flank surface. The ridge line intersecting with 4 acts as a substantial cutting edge.

  The honing surface 8 includes the corner blade 7A of the cutting blade 7 and the portion extending from the corner blade 7A to the one side surface of the two side surfaces which are the flank 4 of the base body 1A of the insert body 1. The honing angle with respect to the rake face 2 is made constant, and the width formed by the honing face 8 in the direction along the rake face 2 in the cross section perpendicular to the cutting edge 7 is also made constant as shown in FIG. The portion of the cutting blade 7 extending from the corner blade 7 to the one side surface is the main cutting blade 7B when the cutting insert is attached to the cutting edge exchangeable cutting tool as described above. In the form, it extends linearly as a tangent line that touches a ¼ arc formed by the corner blade 7A.

  On the other hand, a portion of the cutting blade 7 extending from the corner blade 7A opposite to the main cutting blade 7B to the side of the other side surface as the flank 4 is a sub-cutting blade 7C. Here, when the intersection ridgeline of the honing surface 8 and the flank 4 substantially acting as the auxiliary cutting edge 7C is viewed from the direction perpendicular to the rake face 2 along the thickness direction, a corner blade is obtained. 7A is formed so as to form a convex curve that once protrudes toward the outside of the insert body 1 as it moves away from the corner portion C, and then retreats after passing through the protruding end portion P.

  However, the radius of curvature of the convex curve formed by the intersecting ridge line of the secondary cutting edge 7C is extremely large with respect to the radius of the arc formed by the corner blade 7A of the corner portion C, and is formed to be substantially linear. Further, on the side opposite to the corner portion C, the intersecting ridge line of the auxiliary cutting edge 7C intersects the obtuse angle with respect to the portion forming the convex curve having a large curvature radius when viewed from the direction facing the rake face 2. Thus, the straight line receding from the virtual extension line of the convex curve.

  In this embodiment, the honing surface 8 formed along the sub cutting edge 7C is configured to gradually increase the honing angle as the distance from the corner portion C increases. Further, the honing surface 8 along the secondary cutting edge 7C is a boundary surface between the superhard sintered body 6A portion on the corner portion C side of the layered sintered body 6 and the cemented carbide 6B portion exposed on the rake face 2. It extends beyond Q to the cemented carbide 6B portion, that is, the boundary surface Q intersects the honing surface 8 of the secondary cutting edge 7C.

  More specifically, the honing angle of the honing surface 8 along the auxiliary cutting edge 7C is from the corner blade 7A to the projecting end portion P when viewed from the direction facing the rake face 2, and the corner blade 7A and the main cutting edge The blade 7B has a constant angle equal to that of the blade 7B, and gradually increases from the protruding portion P toward the opposite side of the corner portion C. Accordingly, the honing surface 8 of the auxiliary cutting edge 7C has a twisted surface at the portion where the honing angle increases.

  In addition, the honing surface 8 along the secondary cutting edge 7C has a honing width in the direction along the rake face 2 in a cross section orthogonal to the secondary cutting edge 7C. The constant width is equal to the honing surface 8 of the main cutting edge 7B, and the width gradually increases as the distance from the protruding portion P to the corner portion C increases. Here, the honing surface 8 of the auxiliary cutting edge 7C is on the side opposite to the corner portion C from the protruding end portion P, as shown in FIG. 5, and intersects with the rake surface 2 when viewed from the direction facing the rake surface. Has a convex curve shape.

  In this way, the honing angle and the honing width of the honing surface 8 along the secondary cutting edge 7C gradually increase toward the opposite side of the corner portion C, so that the secondary cutting edge 7C substantially acts as a cutting edge. When the ridge line between the honing surface 8 and the flank 4 is viewed from the direction facing the flank 4 along the rake face 2, the ridge line 2 extends toward the rake face 2 from the protrusion P toward the opposite side of the corner C. On the other hand, it is retracted so as to be gradually separated in the thickness direction and extends toward the seating surface 3 side.

  However, the amount of receding of this intersecting ridge line is two ends R, that is, the end face R opposite to the corner part C of the auxiliary cutting edge 7C located in the cemented carbide 6B part of the layered sintered body 6, that is, the flank 4 Even at the position where the cemented carbide 6B is interrupted on the other side surface among the side surfaces, the retreat amount from the position in the thickness direction at the projecting end portion P is within the range of 0.005 mm or more and 0.02 mm or less. .

  As described above, the cutting insert configured as described above is detachably attached to a face mill, which is, for example, a cutting edge-replaceable rolling tool shown in FIGS. 7 to 9, and is finished by cutting. Used for cutting. This face mill is formed of a steel material or the like and has a disk shape centered on the axis O, and is sent in a direction perpendicular to the axis O while being rotated in the tool rotation direction T around the axis O. Then, cutting is performed by the cutting blade 7 of the cutting insert.

  A plurality of chip pockets 12 are formed on the outer periphery of the lower end portion (the lower portion in FIG. 7) of the tool body 11 in the axis O direction, and are spaced apart from each other in the circumferential direction. The above-described insert mounting seats 13 on which the cutting inserts are seated are formed on the rear side. The insert mounting seat 13 includes a bottom surface 13A facing the tool rotation direction T and a wall surface 13B facing the outer peripheral side of the tool main body 11 and moving toward the lower end side in the axis O direction. The surface 3 is brought into close contact with the bottom surface 13A, and the one of the parallel side surfaces is brought into contact with the wall surface 13B and is seated.

  Further, a recess is formed on the insert mounting seat 13 on the side of the tool rotation direction T so as to open to the chip pocket 12, and a mounting wedge 14 is accommodated in this recess, and this mounting wedge is accommodated by a clamp screw. By screwing 14 into the inner peripheral side of the tool body 11, the mounting wedge 14 presses the inclined plane 1 </ b> B of the insert body 1 and the cutting insert is attached to the insert mounting seat 13. In the recess formed on the upper end side in the axis O direction of the insert mounting seat 13 (upper side in FIGS. 7 and 9), an adjustment wedge 15 for adjusting the runout in the axis O direction of the cutting blade 7 of the cutting insert, A retaining screw 16 for preventing the adjustment wedge 15 from coming off is attached.

  In this way, the cutting insert attached to the insert attachment seat 13 is such that the corner portion C of the layered sintered body 6 is located on the outer periphery of the lower end of the tool body 11 and the rake face 2 is directed in the tool rotation direction T. The main cutting edge 7B formed on the layered sintered body 6 is projected to the outer peripheral side of the tool main body 11 so as to extend substantially parallel to the axis O when viewed from the tool rotation direction T side. The tool body 11 is protruded toward the lower end side so as to be substantially positioned on a plane perpendicular to O.

  Further, the cutting inserts mounted on the plurality of insert mounting seats 13 are configured such that the rotation trajectories of the cutting blades 7 coincide with each other with a relatively small cut by the corner blade 7A and the main cutting blade 7B as necessary. In addition to cutting the work material, the machined surface is smoothly finished with the auxiliary cutting edge 7C as the wiper blade. The secondary cutting edge 7C is given a positive radial rake angle and an axial rake angle.

  In the cutting insert having the above-described configuration used for cutting the work material in this manner, first, honing is applied to the cutting edge 7 formed on the layered sintered body 6 disposed on the rake face 2 of the insert body 1. The honing angle of the honing surface 8 is gradually increased as the auxiliary cutting edge 7C moves away from the corner portion C. For this reason, when the secondary cutting edge 7C extending from the corner C is used as a wiper blade as described above to finish the processing surface smoothly, the secondary cutting edge 7C, particularly on the opposite side of the corner C, is used. The crossing angle at the crossing ridgeline between the honing surface 8 and the flank 4 that substantially act as a cutting edge can be increased, and the cutting edge strength can be ensured.

  Further, the layered sintered body 6 is provided with an ultra-high hardness sintered body 6A having a high hardness in the corner portion C, whereas on the opposite side of the corner portion C of the auxiliary cutting edge 7C. The cemented carbide 6B is exposed, and the boundary surface Q between the cemented carbide 6B of the layered sintered body 6 and the cemented carbide 6B intersects with the honing surface 8 of the auxiliary cutting edge 7C. That is, on the side opposite to the corner portion C, the auxiliary cutting edge 7C is formed in this cemented carbide 6B portion.

  For this reason, according to the cutting insert having the above-described configuration, on the end R side opposite to the corner portion C of the sub-cutting blade 7C, sufficient hardness even if it is lower than the ultra-high hardness sintered body 6A, and Toughness higher than that of the ultra-high hardness sintered body 6A can be provided. Accordingly, in combination with the fact that the cutting edge strength can be ensured as described above, the cutting edge 7 can be intermittently cut as in the case of a rolling process using a cutting tool with an exchangeable cutting edge such as a face mill. Even when the cutting load acts intermittently, it is possible to prevent the cutting edge 7 from being chipped or chipped at the end R of the auxiliary cutting edge 7C, and to perform stable cutting over a long period of time. It becomes possible.

  In the cutting insert of the present embodiment, the boundary surface Q between the ultra-hard sintered body 6A of the layered sintered body 6 and the cemented carbide 6B is intersected with the honing surface 8 of the auxiliary cutting edge 7C in this way. The layered sintered body 6 has a constant thickness of the super-hard sintered body 6A and the cemented carbide 6B on the one side surface which becomes the flank 4 of the main cutting edge 7B, and the flank of the sub-cutting edge 7C. As the distance from the corner C is increased, the thickness of the ultra-high hardness sintered body 6A is gradually reduced to 0 on the way, and the cemented carbide 6B is The thickness of the ultra-high hardness sintered body 6A is made constant until the thickness becomes zero, and then gradually becomes thinner. For example, the boundary surface Q is perpendicular to the rake face 2, That is, in FIG. 5, all of the corner portion C side of the boundary surface Q is an ultra-high hardness sintered body 6. Is a, side opposite all even if being a cemented carbide 6B, it can be assumed that at the side opposite to the corner portion C and the minor cutting edge 7C formed on cemented carbide 6B portion from this.

  However, in that case, since the bonding area of the super-hard sintered body 6A portion of the layered sintered body 6 to the base body 1A of the insert body 1 becomes large, the base body 1A made of cemented carbide is layered as described above. When the sintered body 6 is joined by brazing, there is a possibility that sufficient joining strength cannot be obtained due to the low joining property between the cemented carbide alloy and the ultra-high hardness sintered body. In this case, since the portion occupied by the expensive ultra-high hardness sintered body 6A in the layered sintered body 6 also increases, the ultra-high hardness sintered body 6A portion of the sub-cutting blade 7C is used as in this embodiment. The boundary surface Q intersects with the flank 4 on the side of the corner C of the layered sintered body 6 and is opposite to the corner C of the sub-cutting blade 7C so as to gradually become thinner toward the end R side. Thus, it is desirable that the rake face 2 on the layered sintered body 6 also intersects at an acute angle.

  In the present embodiment, when viewed from the direction facing the rake face 2, the intersecting ridge line between the honing surface 8 and the flank 4 of the auxiliary cutting edge 7C forms a convex curve having a large curvature radius. When the sub-cutting edge 7C is used as a wiper blade with this intersecting ridge line as a substantial cutting edge, the finished surface of the work material has a cross-sectional shape in which a concave curve having a large curvature radius is conversely provided. For this reason, for example, compared with the case where the secondary cutting edge has a straight line shape, even if the secondary cutting edge 7C is inclined, the joint between the concave curves of the finished surface is prevented from protruding greatly, that is, the finished surface. Therefore, a smoother finished surface can be obtained.

  Further, in the present embodiment, the intersection ridgeline between the honing surface 8 and the flank 4 of the auxiliary cutting edge 7C that forms a convex curve having a large radius of curvature when viewed from the direction facing the rake face 2 is raked. When viewed from the direction facing the flank 4 of the secondary cutting edge 7C along the surface 2, the rake face 2 gradually recedes from the protruding portion P of the convex curve toward the opposite side of the corner portion C. Therefore, the width of the honing surface 8 when viewed from the direction facing the flank 4 is gradually increased toward the opposite side to the corner portion C. Therefore, the width on the opposite side to the corner portion C is increased. It is possible to improve the strength of the auxiliary cutting edge 7C and more reliably prevent the chipping and chipping.

  However, if the amount of retreat of the intersecting ridge line retreating from the rake face 2 becomes too large, a clearance angle is given to the flank 4 on which the intersecting ridge line is formed. When viewed, the radius of curvature of the convex curve formed by the intersecting ridge line becomes smaller on the side opposite to the corner part C, that is, the intersecting ridge line is too far from the finished surface of the work material on the opposite side to the corner part C. As described above, when the auxiliary cutting edge 7C is inclined, a smooth finished surface cannot be obtained, and the finished surface roughness may be deteriorated or the finished surface may be wavy. On the other hand, if the retraction amount is too small as it is close to 0 mm, there is a possibility that the above effect cannot be obtained. The difference in the retraction amount in the thickness direction from the rake face 2 at the end R of the auxiliary cutting edge 7C opposite to the part C is set to 0.005 mm or more and 0.02 mm or less as in the present embodiment. Is desirable.

  Furthermore, in this embodiment, the width in the direction along the rake face 2 of the honing surface 8 along the sub cutting edge 7C is gradually increased from the protruding portion P toward the opposite side to the corner portion C. Has been. Therefore, when the cross ridge line is retracted from the rake face 2 when viewed from the direction facing the flank 4 as described above, the actual honing width of the honing face 8, that is, the auxiliary cutting edge 7C. Since the width of the honing surface 8 in the cross section perpendicular to the intersecting ridge line can be gradually increased toward the opposite side of the corner portion C, it is possible to more reliably prevent the chipping and chipping.

  Next, the rake face 2 of the intersecting ridge line between the honing surface 8 and the flank 4 of the secondary cutting edge 7C when viewed from the direction facing the flank 4 of the secondary cutting edge 7C along the rake face 2 as described above. With respect to the amount of retreat with respect to the above, it is demonstrated that it is desirable that the amount is 0.02 mm or less by giving an example. In this example, the amount of retraction is 0 by changing the honing angle of the honing surface 8 at the projecting end portion P of the intersecting ridge line and the honing angle at the end portion R of the auxiliary cutting edge 7C based on the above embodiment. 5 types of cutting inserts of 0.005 mm or more and 0.02 mm or less were manufactured, and these were attached to the blade-tip-replaceable face mill shown in FIGS. 7 to 9 to perform a cutting test. The condition of the auxiliary cutting edge 7C, such as the presence or absence of abnormal wear and the magnitude of flank wear, is confirmed, and the finished surface roughness and finished surface waviness (arithmetic average roughness Ra and maximum height waviness Wz in JIS B0601: 2001) ) Was measured. Table 1 shows these cutting inserts as Examples 1 to 5 together with the honing angle and the amount of retraction.

  Moreover, as a comparative example with respect to these Examples 1 to 5, the honing angle at the projecting end portion P and the honing angle at the end portion R of the intersecting ridge line of the secondary cutting edge 7C remain constant, and therefore the retraction amount is 0. Manufactures two types of cutting inserts and two types of cutting inserts with a large honing angle at the end R so that the amount of retraction of the intersecting ridge line from the projecting end P to the end R exceeds 0.02 mm Then, a cutting test was performed under the same conditions as in Examples 1 to 5, and the state of the secondary cutting edge 7C was also confirmed, and the finished surface roughness and finished surface waviness were measured. These are referred to as Comparative Examples 1 to 4, and the results are shown in Table 1 together with the honing angle and the retraction amount.

  In the cutting inserts of Examples 1 to 5 and Comparative Examples 1 to 4, the basic shape of the insert body 1 is GDCN2004PDFR3 type manufactured by Mitsubishi Materials Corporation (the radius of the corner blade 7A is 1.2 mm), and the layered sintered body 6 is super High hardness sintered body 6A is CBN of MB730 manufactured by Mitsubishi Materials Corporation, cemented carbide 6B is equivalent to HTi manufactured by Mitsubishi Materials Corporation, and the curvature radius of the convex curve formed by the intersecting ridge line of the secondary cutting edge 7C is 250 mm. The length of the auxiliary cutting edge is 3 mm, and the protruding end P is disposed at a position of 1 mm from the end of the corner blade 7A along the auxiliary cutting edge 7C, and from the protruding end P along the auxiliary cutting edge 7C. The boundary surface Q appears at a position of 1 to 1.5 mm on the opposite side to the corner portion C.

  Further, the conditions of the cutting test were as follows: single blade cutting with only one cutting insert attached to the tool body 11 of a face-changing face mill, cutting speed 1000 m / min, feed rate 0.2 mm / tooth, A dry cutting with a cutting depth of 0.5 mm was performed, and a hydraulic casting block equivalent to FC300 as a work material was cut in a range of 250 mm × 110 mm.

  From the results shown in Table 1, the honing angle of the secondary cutting edge 7C on the honing surface 8 gradually increases from the projecting end portion P to the end portion R of the intersecting ridge line. However, in Examples 1 to 5 in which the retraction amount is 0.02 mm or less, the sub cutting edge 7C is not damaged, chipped, or abnormally worn, and the flank wear is small. It can be seen that the roughness of the finished surface and the waviness of the finished surface are also kept small.

  On the other hand, in Comparative Examples 1 to 4, the honing angle is the same at the projecting end portion P and the end portion R, and therefore when the crossed ridge line of the auxiliary cutting edge 7C is viewed from the direction facing the flank 4. In Comparative Examples 1 and 3 in which the retraction amount is set to 0 without retreating with respect to the rake face 2, in Comparative Example 3, the end R of the auxiliary cutting edge 7C is welded and chipping occurs. When 1, the sub-cutting edge 7C was deficient and the cutting test had to be stopped, and the finished surface roughness and waviness could not be measured. On the other hand, in Comparative Examples 2 and 4 where the difference in the honing angle between the projecting end portion P and the end portion R is large and the retreat amount of the intersecting ridge line of the auxiliary cutting edge 7C is more than 0.02 mm, Although no chipping or chipping as in No. 3 occurred, it was confirmed that the finished surface roughness and finished surface waviness were remarkably increased.

DESCRIPTION OF SYMBOLS 1 Insert body 1A Base body of insert body 1 Rake face 4 Relief face 5 Recessed part 6 Layered sintered body 6A Super hard sintered body 6B Cemented carbide 7 Cutting edge 7A Corner blade 7B Main cutting edge 7C Sub cutting edge (wiper blade) )
8 Honing surface 11 Tool body 13 Insert mounting seat C Corner portion P Projection end of intersection ridge line of honing surface 8 and flank surface 4 Boundary between super-hard sintered body 6A of layered sintered body 6 and cemented carbide 6B Surface R The edge of the secondary cutting edge 7C opposite to the corner C

Claims (3)

  On the rake face of the insert body, a layered sintered body obtained by sintering an ultra-high hardness sintered body and a cemented carbide alloy in layers, the ultra-high hardness sintered body is located at the corner portion of the rake face, and the rake A cutting blade that is disposed so as to face the surface side and that extends from the corner portion on the side ridge portion of the rake face on the layered sintered body is formed. A honing surface is formed in which the honing angle gradually increases as the distance from the surface is increased, and the boundary surface between the ultra-high hardness sintered body and the cemented carbide in the layered sintered body intersects with the honing surface of the cutting edge. Cutting insert characterized by being made.   When viewed from the direction facing the rake face, the intersecting ridge line between the honing face of the cutting edge and the flank face formed on the layered sintered body protrudes once as it moves away from the corner portion, and passes through the protruding end portion. A convex curve having a radius of curvature larger than that of the corner portion that retreats later, and when viewed from the direction facing the flank surface along the rake face, from the protruding end portion to the opposite side of the corner portion. The crossed ridge line is retreated from the tip end to the end of the cutting blade on the side opposite to the corner portion of the layered sintered body. The cutting insert according to claim 1, wherein the amount is in a range of 0.005 mm or more and 0.02 mm or less.   3. The cutting insert according to claim 1, wherein the honing surface gradually increases in width in a direction along the rake face as the distance from the corner portion increases. 4.

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