JP2009012116A - Cutting insert - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting insert allowing improvement of accuracy and quality of a cutting surface of a workpiece, extending of a service life of the insert, reduction of cutting resistance, exact formation of a front cutting edge with prescribed dimensional accuracy, and further simplifying finishing for removing a left core, in the cutting insert with a convenient side suitable for use for cutting-off workpiece, in particular. <P>SOLUTION: In this cutting insert, a cutting edge part 2 having a rake face 5 provided with the front cutting edge 4 extending in a direction intersecting the longitudinal direction is formed at an end part of an insert main body 1 extending in the longitudinal direction. The front cutting edge 4 is provided with: an inclined part 9 inclined to be gradually retreated in the longitudinal direction as it goes from one end part of the front cutting edge 4 toward the other end part side viewed from a direction opposed to the rake face 5; and a perpendicular part 10 extending perpendicularly in the longitudinal direction from the other end part of the front cutting edge 4 to the one end side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cutting insert that is used for grooving of a work material or particularly parting off in turning, and more particularly to a cutting insert having a right and left hand on a front cutting edge.

  In such a cutting insert used especially for cutting off the work material, the front cutting edge to be cut into the work material is viewed from the opposite side from one of the left and right ends when viewed from the direction facing the rake face. For example, Patent Documents 1 to 3 disclose cutting inserts with a right hand that are formed so as to be inclined with respect to the longitudinal direction of the insert main body toward the other end. According to such a cutting insert, the core portion left immediately before the work material is divided by parting off is cut from the cut surface of the work material located on the other end side of the front cutting edge on one end side. Since it becomes a conical shape that tapers toward the surface, it is difficult for the core to remain on one cut surface side on the one end portion side, and subsequent finishing can be simplified.

However, in such a cutting insert, since the front cutting edge is inclined, the cutting edge length tends to increase and the cutting resistance tends to increase, and this cutting resistance is the other end of the front cutting edge. Therefore, there is a problem that holding of the cutting insert tends to become unstable. Therefore, for example, in Patent Documents 4 and 5, the front cutting edge has a concave curved shape with one end projecting from the other end, and a notch is provided to reduce the resistance by dividing the chips. Or a recess with one end protruding from the other end and the front cutting edge retracted from the line connecting the both ends and tilted in the opposite direction on the one end side and the other end side. There has been proposed a configuration in which cutting forces acting in the lateral direction cancel each other out by forming a V shape.
JP-A-8-229705 Special table 2003-509224 gazette JP 2007-69291 A Japanese Utility Model Publication No. 61-50603 Japanese Utility Model Publication No. 7-11204

  However, when the front cutting edge is formed in a concave curved shape as in the cutting insert described in Patent Document 4 and the notch is provided in a recessed manner to divide the chips, the divided chips are separated from one end side of the front cutting edge and the other. Since it flows out toward the cut surface of the work material located on each side on the end side, these cut surfaces may be damaged by chips, and the accuracy and quality may be impaired. The same applies to the case where the both end portions of the front cutting edge are inclined in opposite directions to form a concave V shape like the cutting insert described in Patent Document 5.

  Further, as described in Patent Documents 4 and 5, when the front cutting edge is formed into a concave curved shape or a concave V shape, both ends of the front cutting edge are both tapered so that chipping is likely to occur. The risk of shortening the insert life is increased. Furthermore, even if the cutting forces acting in the lateral direction cancel each other out at both ends, the cutting edge length of the front cutting edge itself remains long as in Patent Documents 1 to 3, and thus acts on the entire front cutting edge. Cutting resistance is not reduced. Furthermore, it is not easy to reliably form a front cutting edge whose both end portions are tapered in this way with a predetermined dimensional accuracy so that one end portion projects beyond the other end portion.

  On the other hand, even in the cutting inserts described in Patent Documents 1 to 3 and the cutting inserts described in Patent Documents 4 and 5, since the core remains on the other cut surface, the work material was cut by parting off. Later, a finishing process must be performed to remove the core, but if these cutting inserts are used to perform a finishing process to remove the core as they are, cutting is performed with an inclined or curved cutting blade. Therefore, it is difficult to finish the other cut surface smoothly. Therefore, this finishing process has to use an unintentional cutting insert whose front cutting edge is perpendicular to the longitudinal direction, and the finishing process has not been sufficiently simplified.

  The present invention has been made under such a background, and particularly in a cutting insert suitable for use in the parting-off of the work material as described above, the accuracy and quality of the cut surface of the work material is improved. In addition to improving insert life, extending insert life and reducing cutting force, the front cutting edge can be accurately formed to the specified dimensional accuracy, and the finishing process to remove the remaining core is further simplified. The aim is to provide a cutting insert that can be urged.

  In order to solve the above-mentioned problems and achieve such an object, the present invention provides a rake face provided with a front cutting edge extending in a direction intersecting the longitudinal direction at the end of the insert body extending in the longitudinal direction. A cutting edge portion is formed, and the front cutting edge is gradually retracted in the longitudinal direction from one end portion of the front cutting edge toward the other end side when viewed from the direction facing the rake face. And a vertical portion extending perpendicularly to the longitudinal direction from the other end portion of the front cutting edge toward the one end portion side.

  Therefore, in such a cutting insert, even if one end portion side of the front cutting edge is an inclined portion, the other end portion is a vertical portion perpendicular to the longitudinal direction. The cutting edge length can be shortened and cutting resistance acting on the entire front cutting edge can be suppressed as compared with the case where the cutting edge is inclined in the same direction as in FIG. In addition, since the other end side of the front cutting edge is a vertical portion and does not taper in this way, it is possible to prevent the occurrence of chipping, and the front cutting edge can be used with reference to the vertical portion perpendicular to the longitudinal direction. It can be accurately formed according to the desired dimensional accuracy, and the core remaining on the cut surface of the work piece on the other end side after parting off is used as it is in the insert body by the vertical part using the cutting insert as it is. It can be removed and finished without causing runout.

  Further, since the other end portion side of the front cutting edge is a vertical portion in this way, the chips generated by the front cutting edge flow out in the longitudinal direction. As a result, the chips generated by the inclined portion by being pulled by the inclined portion can be prevented from flowing toward the cut surface of the work piece on the one end side where the inclined portion is formed. Therefore, the entire chip generated by the front cutting edge can be discharged in the longitudinal direction of the insert body through both the cutting surfaces of the work material, and the cutting surface can be prevented from being damaged by the cutting chips. Become.

  Here, in order to cause the chips generated by the front cutting edge to flow out in the longitudinal direction so that the chips generated by the inclined portion are pulled by the chips generated by the vertical portion, the chips are not pulled. The inclined portion is preferably formed in a concave curve shape in which at least the vertical portion side smoothly contacts the vertical portion when viewed from the direction facing the rake face. In addition, although the whole inclined part may be such a concave curve shape, in order to surely prevent chipping on the one end part side of the front cutting edge, at least the rake face on the one end part side. It is desirable to extend in a straight line when viewed from the direction opposite to.

  Further, it is desirable that the inclined portion is inclined in a direction intersecting at an angle of 3 ° to 50 ° with respect to the vertical portion at one end portion of the front cutting edge as viewed from the direction facing the rake face. If the angle is larger than this range, the inclined portion of the front cutting edge may be tapered and chipping may easily occur on one end side. On the other hand, if the angle is smaller than this range, the front cutting edge is close to a straight line extending straight from the vertical portion, and it may be difficult to form a tapered core on the work material during the parting process. Occurs.

  As described above, according to the present invention, it is possible to improve the machining accuracy and the quality by preventing the cut surface of the work material from being damaged by the chips, particularly in a cutting insert having a parting process for the work material. At the same time, chipping at the end of the front cutting edge can be prevented and the insert life can be extended. Further, cutting resistance acting on the entire front cutting edge can be reduced to promote efficient machining. Further, the front cutting edge can be accurately formed with a predetermined dimensional accuracy on the basis of the vertical portion, and finishing processing can be performed to remove the remaining core using the cutting insert as it is. Therefore, it becomes possible to further simplify the parting process.

  1 to 6 show a first embodiment of the present invention. In the present embodiment, the insert body 1 is formed of a hard material such as cemented carbide and has a substantially square shaft shape (square column shape) extending along the axis L. The insert body 1 is perpendicular to the axis L and is in the longitudinal direction. (Axis L direction. Left and right direction in FIGS. 2 to 5) A plane M located in the center, and a width direction of the insert body 1 perpendicular to the plane M (vertical direction in FIGS. 2 and 5; FIG. 6) (Left and right direction) 180 ° rotationally symmetric with respect to a line of intersection O with a plane N located in the center and extending in the thickness direction of the insert body 1 including the axis L (vertical direction in FIGS. 3, 4 and 6). It is formed into a shape. Accordingly, the axis L is perpendicular to the intersecting line O.

  A cutting blade portion 2 is formed at the end portion (both ends) of the insert body 1 in the longitudinal direction. The cutting blade portion 2 includes a pair of horizontal cutting blades 3 extending in the longitudinal direction, and a lateral portion thereof. A rake face 5 having a front edge 4 that intersects the longitudinal direction and extends in the width direction at the side ridge portion is formed between the tips of the cutting edges 3 so as to face the thickness direction. . Here, the rake face 5 has a substantially rectangular shape extending in the longitudinal direction as shown in FIG. 2 in a plan view as viewed from a direction perpendicular to the axis L and facing the rake face 5 in the thickness direction. ing. Further, corner blades 6 each having a substantially ¼ arc shape in the plan view are formed at a pair of corner portions intersecting the horizontal cutting blade 3 at both ends of the front cutting blade 4.

  Note that the upper surface portion 7 of the insert body 1 facing the same side as the rake face 5 in the thickness direction between the cutting edge portions 2 at both ends in the longitudinal direction is shown in FIGS. 3 and 4. The rake face 5 protrudes one step in the thickness direction. Furthermore, the upper surface portion 7 and the lower surface portion 8 of the insert body 1 opposite to the upper surface portion 7 are formed with mounting groove portions 7A and 8A having a V-shaped cross section over the entire length in the longitudinal direction. ing.

  Further, both end surfaces 7B of the upper surface portion 7 facing the longitudinal direction are inclined surfaces that are inclined toward the lower surface portion 8 side toward the cutting blade portion 2 side, A pair of cutout portions 8B are formed around the inner side of the position where both end surfaces 7B of the upper surface portion 7 are cut off in the longitudinal direction. In addition, the part between both the cutting edge parts 2 of this insert main body 1 is made into the symmetrical shape regarding the said plane M and the plane N, respectively.

  Further, the cutting edge portion 2 has a ridge edge 5 with the front edge of the front cutting edge 4, the corner edge 6, and the side cutting edge 3 on the leading edge side, as shown in FIGS. 1, 3, and 4. The portion of the part has a negative rake face part 5A that gradually recedes in the thickness direction toward the lower face part 8 side toward the tip side. On the other hand, a portion on the rear end side from the negative rake face portion 5A is a positive rake face portion 5B that gradually cuts back in the thickness direction toward the lower face portion 8 side toward the rear end side, and further this positive rake face portion. The rear end side of the surface portion 5B is a flat surface portion 5C perpendicular to the thickness direction, and is continuous with the end surface 7B of the upper surface portion 7.

  Further, the rake face 5 has a range from a position spaced from the front cutting edge 4 of the negative rake face part 5A in the longitudinal direction to the middle of the flat face part 5C, and in the transverse direction, A concave chip breaker 5D is formed in a range between the blade 3 and a position equidistant from each other. The chip breaker 5D has a concave curved surface in the cross section along the plane N, and in the cross section parallel to the plane M, the chip breaker 5D has a lower surface portion from the rake face 5 toward both sides in the width direction. After inclining to the 8 side, this central portion has a trapezoidal groove shape extending perpendicular to the thickness direction. Further, the distance between the chip breaker 5D and the front cutting edge 4 is smaller than the distance between the chip breaker 5D and the side cutting edge 3, and the negative scoop of the rake face 5 is provided between the front cutting edge 4 and the chip breaker 5D. The surface portion 5A is left with a very small constant width.

  Then, as shown in FIG. 2, the front cutting edge 4 is viewed from the direction facing the rake face 5, and the other end (lower end in FIG. 2) from one end (upper end in FIG. 2). And the vertical part 10 extending perpendicularly to the longitudinal direction from the other end part toward the one end part side. . Further, in the present embodiment, the inclined portion 9 is smoothly in contact with an arc formed by the corner blade 6 on one end portion of the front cutting edge 4 in the plan view, and is inclined linearly toward the other end portion. The linear portion 9A recedes in the longitudinal direction and the curved portion 9B having a concave curved shape that smoothly contacts the linear portion 9A and the vertical portion 10 in the same plan view.

  Of these, the inclined portion 9 has a cutting edge length longer than that of the vertical portion 10, and among them, the linear portion 9A is formed to be substantially the same length or slightly longer than the curved portion 9B. . Further, the curved portion 9B has a concave arc shape in the above-described plan view, and the radius thereof is sufficiently larger than the radius of the arc formed by, for example, the corner blade 6, and in the present embodiment, both the side cutting blade 3 and the corner blade 6 The width between the contact points, that is, the cutting width is set larger. Further, the vertical portion 10 is formed so as to be smoothly in contact with an arc formed by the corner blade 6 on the other end side of the front cutting edge 4 in the same plan view. On the other hand, the inclined portion 9 extends in a direction in which a tangent to the corner blade 6 at one end thereof (in this embodiment, the straight portion 9A) intersects with an angle θ of 5 °.

  Further, the pair of side cutting blades 3 are also in smooth contact with the corner blades 6 at both ends of the front cutting blade 4 and retreat in the width direction from each corner blade 6 toward the rear end side of the cutting blade portion 2. The back taper is slightly inclined and is provided with an equal back taper so as to approach each other on the plane N side. Since the rake face 5 is constituted by the negative rake face part 5A, the positive rake face part 5B, and the flat face part 5C as described above, the horizontal cutting edge 3 is also uneven in the thickness direction. Will be formed.

  On the other hand, the front end face of each cutting edge portion 2 facing the longitudinal direction is a flank 11 of the front cutting edge 4, and both side faces facing the width direction are flank 12 of the pair of side cutting edges 3. Here, in the cutting insert of this embodiment, these flank surfaces 11 and 12 are separated from the rake face 5 including the intersecting ridge line portions of the flank surfaces 9 and 10 connected to the corner blade 6 in the thickness direction. The positive flank is inclined so as to gradually recede in the longitudinal direction and the width direction as it goes to the lower surface 8 side, and a clearance angle is given to the front cutting edge 4 and the side cutting edge 3. It is considered as a positive type insert.

  Among these, the flank 11 of the front cutting edge 4 includes the inclined portion 9 and the vertical portion 10 as described above, and further includes the linear portion 9A and the curved portion 9B of the inclined portion 9. As it is configured, the inclined flat surface portion 11A that is connected to the linear portion 9A of the inclined portion 9 and is inclined so as to gradually recede in the longitudinal direction as it goes from the one end to the other end of the front cutting edge 4; The concave curved surface portion 11B that is continuous with the curved portion 9B and that is in contact with the inclined flat surface portion 11A and gradually recedes toward the other end side, and the flat surface that is continuous with the vertical portion 10 and is in contact with the concave curved surface portion 11B. And a vertical plane portion 11C extending perpendicularly to N. In this embodiment, the clearance angle of the front cutting edge 4 formed by the inclined flat surface portion 11A, the concave curved surface portion 11B, and the vertical flat surface portion 11C with respect to the linear portion 9A, the curved portion 9B, and the vertical portion 10 is as follows. The one end to the other end are substantially constant.

  Further, the end surface 13 and the side surface 14 of the insert main body 1 are formed between the clearance surfaces 11 and 12 of the cutting edge portion 2 and the lower surface portion 8 so as to extend in parallel with the thickness direction. Therefore, the end face 13 is located inside the front cutting edge 4 in the longitudinal direction, and the both side faces 14 are located inside the pair of horizontal cutting edges 3 in the width direction. Of these, the side surface 14 is generally a surface extending from the portion between the flank 12 and the lower surface portion 8 of the both cutting edge portions 2 to the side surface of the insert body 1 between these cutting edge portions 2. The plane is parallel to the plane N.

  On the other hand, in the present embodiment, the end surface 13 is configured such that one end portion side of the front cutting edge 4 is a flat surface portion 13A perpendicular to the axis L, that is, perpendicular to the longitudinal direction, and the other end portion of the front cutting edge 4 is. On the side, a relief portion 13B is set back in the longitudinal direction with respect to the flat surface portion 13A. The escape portion 13B is an inclined surface that intersects the flat surface portion 13A at an obtuse angle and gradually recedes toward the other end portion of the front cutting edge 4, and in this embodiment, in particular, is an inclined flat surface. As shown in FIG. 5 in a bottom view facing the lower surface portion 8 of the insert body 1, the insert body 1 is formed to be inclined at an angle β with respect to the flat surface portion 13A.

  In addition, the intersection ridgeline part of this end surface 13 and the said side surface 14 is continued to the intersection ridgeline part of the relief surfaces 9 and 10 continued to the said corner blade 6, and the said flat surface part 13A and the relief part 13B, and the side surface 14 of each side, It is a cylindrical surface that touches smoothly. Further, between these tangent lines of the cylindrical surface and the end surface 13, as shown in FIG. 6 when viewed from the direction facing the end surface 13 along the longitudinal direction, the area of the flat surface portion 13A is reduced. More specifically, the cross-ridge line P between the flat surface portion 13A and the relief portion 13B is located closer to the other end portion of the front cutting edge 4 than the plane N, 13 A of flat surface parts are formed so that it may extend to the other end part side from the plane N. In this embodiment, the intersecting ridge line P extends parallel to the plane N and intersects the concave curved surface portion 11B of the flank 11.

  Furthermore, in this embodiment, between this end surface 13, between the flat surface portion 13A on one end side of the front cutting edge 4 thus made perpendicular to the longitudinal direction, and the flank surface 11 that is a positive flank surface. As shown in FIG. 3, an overhang portion 15 is formed which is recessed so as to further recede in the longitudinal direction with respect to the extended surface Q of the positive clearance surface. In the present embodiment, the overhang portion 15 has a slope where the portion where the inclined flat portion 11A on the one end side of the front cutting edge 4 and the flat surface portion 13A intersect is a positive flank. The flat surface 11A is formed so as to be cut out by an inclined surface that gradually recedes at an angle α with respect to the extended surface Q as it crosses an obtuse angle and moves away from the front cutting edge 4 side.

  Accordingly, the intersecting ridge line R between the overhang portion 15 and the flat surface portion 13A is located closer to the front cutting edge 4 than the virtual intersecting ridge line between the extended surface Q and the flat surface portion 13A. As shown in FIG. 6, it extends perpendicularly to the plane N. In addition, the crossing angle between the overhang portion 15 and the flat surface portion 13A is substantially constant along the cross ridge line R. Therefore, the length of the overhang portion 15 in the thickness direction and the longitudinal length from the flat surface portion 13A. The protruding amount in the direction gradually increases toward one end of the front cutting edge 4. The overhang portion 15 is connected to the flank 12 so that the intersecting ridge line portion between the inclined flat surface 11A and the flank 12 connected to the corner blade 6 on one end side of the front cutting edge 4 is also cut out. Has been.

  On the other hand, on the other end portion side of the front cutting edge 4 opposite to the side on which the overhang portion 15 is formed, the inclined flat surface portion 11A, the concave curved surface portion 11B, and the vertical flat surface portion which are positive flank surfaces 11C is directly crossed with the flat surface portion 13A and the escape portion 13B of the end surface 13 as they are. For this reason, in this embodiment, the intersection ridgeline S between the flank 11 and the end surface 13 on the other end side of the front cutting edge 4 with respect to the overhang portion 15 is an intersection with the intersection ridgeline R as shown in FIG. Extends toward the front cutting edge 4 toward the other end side, and extends in a direction away from the front cutting edge 4 after approaching the front cutting edge 4 at the intersection with the intersecting ridgeline P. .

  In this embodiment, since the insert body 1 is formed to be 180 ° rotationally symmetric with respect to the intersecting line O as described above, such flank surfaces 11 and 12 are formed at both ends in the longitudinal direction. Further, the cutting edge portion 2, the end surface 13 on which the flat surface portion 13A and the relief portion 13B are formed, and the overhang portion 15 are provided.

  The cutting insert of this embodiment configured as described above has a mounting groove portion 7A, 8A formed in the upper and lower surface portions 7, 8 of the insert body 1 in an insert mounting seat formed in a holder of an insert detachable turning tool. By being in contact with and sandwiched between a pair of jaws having a V-shaped cross section facing each other, one of the cutting blades 2 is held by this holder in a protruding state. Further, at this time, on the end surface 13 connected to the flank 11 of the other cutting edge portion 2, the flat surface portion 13A is formed to be perpendicular to the axis L between the pair of jaw portions of the insert mounting seat. It is made to contact | abut to a contact surface, and, thereby, the insert main body 1 is supported and positioned by this other cutting blade part 2 side in the longitudinal direction.

  The cutting insert thus held by the holder is fed along the axis L along the axis L in the longitudinal direction to the distal end side of the one cutting edge 2 and is covered by the front cutting edge 4 of the one cutting edge 2. It is used for grooving and parting of the work material. Especially, in the parting process of cutting the work material, one end side of the front cutting edge 4 recedes in the longitudinal direction toward the other end side. Therefore, immediately before the work material is cut, a core that tapers toward the one end is formed around the rotation axis of the work material. When the tip of the workpiece is scraped off, the work material is cut. Accordingly, at this time, the core is left on the other cut surface on the other end side of the front cutting edge 4, but the core is not broken and remains on one cut surface on the one end side in the middle of cutting. Therefore, at the same time as the parting process, this one cut surface can be finished smoothly.

  Furthermore, according to the cutting insert having the above configuration, even when the core remaining on the other cut surface is removed after the work material is cut in this way, the other end side of the front cutting edge 4 is in the longitudinal direction of the insert body 1. Accordingly, the cutting insert can be used as it is to scrape the core by the vertical portion 10 and finish the other cut surface. That is, since the vertical portion 10 that scrapes off the core is perpendicular to the feed direction, the insert body 1 does not run out in the width direction due to the resistance acting during cutting, so that the cutting insert having one cut surface is left as it is. By only feeding to the front end side along the longitudinal direction, the core can be cut and the other cut surface can be finished smoothly, thereby simplifying the finishing process.

  Further, even in such a parting process or a grooving process in which an annular groove is formed on the outer periphery of the work material without reaching the work material, the cutting insert having the above-described configuration is used in this way. Since the end side is the vertical part 10 perpendicular to the longitudinal direction of the insert body 1, the cutting insert described in Patent Documents 1 to 3 in which the entire front cutting edge is inclined, and one end side and the other end side Therefore, the cutting edge length of the front cutting edge 4 can be kept short compared to the cutting inserts described in Patent Documents 4 and 5, which are concave V-shaped inclined in opposite directions. Therefore, it is possible to reduce the cutting resistance acting on the entire front cutting edge 4 during processing, and to perform efficient parting and grooving.

  Furthermore, since the cutting resistance is reduced in this way and the other end portion side of the front cutting edge 4 is set as the vertical portion 10 to ensure a corner angle with the side cutting edge 3, the other end portion side is also particularly tapered. Compared with the cutting inserts described in Patent Documents 4 and 5, it is possible to prevent chipping of the front cutting edge 4 at the other end, and to extend the insert life. In addition, when the cutting blade portion 2 is formed by forming a portion perpendicular to the longitudinal direction of the insert body 1 in this way, when the cutting blade portion 2 is formed, the dimensional accuracy and shape of each portion with the vertical portion 10 as a reference. The accuracy can be ensured accurately and easily, and the management of the dimensional and shape accuracy can be performed based on the vertical portion 10.

  Further, the other end side of the front cutting edge 4 is thus set as the vertical portion 10, so that in the cutting insert, chips generated by the vertical portion 10 during the parting process are along the longitudinal direction of the insert body 1. The chips generated by the inclined portion 9 so as to flow out and be pulled along with this also flow out so as to pass between the cut surfaces of the work material along the longitudinal direction. Therefore, the chip does not collide with one or both of the cut surfaces of the work material and damage the cut surface, and a cut surface with a smoother, finished surface accuracy and quality can be obtained.

  In particular, in the present embodiment, on the vertical portion 10 side of the inclined portion 9, a linear portion 9A of the inclined portion 9 and a curved portion 9B having a concave curved shape that smoothly contacts the vertical portion 10 are formed. Thus, the chips are generated integrally without being divided in the width direction over the entire length of the front cutting edge 4. For this reason, it is possible to reliably guide the chips from the inclined portion 9 to flow out in the longitudinal direction of the insert body 1, and to more effectively prevent the chips from interfering with and scratching the cut surface. It becomes.

  On the other hand, in the cutting insert of the present embodiment, one end portion side of the front cutting edge 4 is a linear portion 9A that is linearly inclined, and thus, for example, a concave arc shape that is continuous with the vertical portion 10 in the present embodiment. Compared with the case where the curved portion 9B is extended to the one end portion side of the front cutting edge 4 with the same radius, a large crossing angle between the front cutting edge 4 and the side cutting edge 3 at this one end portion can be secured. Therefore, according to the present embodiment, it is possible to prevent the chipping from occurring at the one end portion side, and in combination with the fact that the vertical portion 10 at the other end side can prevent the chipping as described above. The insert life can be further extended.

  In the present embodiment, the linear portion 9A on the one end side of the inclined portion 9 of the front cutting edge 4 in a direction facing the rake face 5 perpendicular to the axis L, that is, in a plan view from the direction of the intersection O, is The angle θ formed with respect to the vertical portion 10 is 5 °. However, if this angle θ is too large, the occurrence of chipping is sufficiently caused even if the one end portion side of the inclined portion 9 is formed as the linear portion 9A. There is a risk that it cannot be prevented. On the other hand, if the angle θ is too small, the front cutting edge 4 becomes almost straight and the core is easily broken during parting, so this angle θ is 3 ° to 50 °. It is desirable to set the range. For example, if the angle θ is set in such a range, the inclined portion 9 may be a concave curved curved portion 9B that smoothly contacts the vertical portion 10 as a whole.

  By the way, in the cutting insert with a self-handling which has the part which inclined so that it may recede in the longitudinal direction as the front cutting edge goes from one end to the other end in this way, such a front cutting edge is provided at both ends of the axial insert body. For example, as described also in Patent Documents 1 to 3, such a cutting blade is formed at both ends of the insert body. When forming a flat surface perpendicular to the longitudinal direction together with the part and using the cutting edge of one end of the insert body, the flat surface of the other end is brought into contact with the contact surface of the insert mounting seat. The insert main body is supported and positioned in the longitudinal direction.

  However, in such a cutting insert, if the front cutting edge is inclined over its entire length as described in Patent Documents 1 to 3, both the cutting edges are used as long as the clearance angle of the front cutting edge remains constant. At one end of the front cutting edge that will protrude in the longitudinal direction of the insert body at the part, the flank will cover the flat surface greatly, and it is not possible to secure a sufficient area on this flat surface The seating stability of the insert body on the insert mounting seat may be impaired. On the other hand, on the other end side of the front cutting edge retracted in the longitudinal direction, the amount of protrusion of the front cutting edge from the flat surface is small, so the width of the flank is also small, and the amount of relief between the work material Tends to be insufficient and may cause interference.

  However, in this regard, in the cutting insert described in Patent Document 1, an intermediate surface is formed between the flank and the flat surface, and in the cutting inserts described in Patent Documents 2 and 3, the flank is formed into a twisted surface. By reducing the clearance angle toward the other end of the blade, the area of the flat surface is secured, but in the former case, the portion immediately below the front cutting edge is located on the front cutting edge by the intermediate surface. Since it is notched along the entire length to form an overhang, the cutting edge strength is reduced and damage is likely to occur. In the latter case, the amount of relief is further insufficient on the other end side of the front cutting edge where the relief angle becomes small, and there is a risk that wear of the relief surface or flat surface is promoted or cutting resistance is increased. .

  On the other hand, in the cutting insert having the above-described configuration in which the vertical portion 10 is formed on the other end side of the front cutting edge 4, the angle θ on the one end side of the inclined portion 9 of the front cutting edge 4 is determined by these Patent Documents 1 to 3. Even if it is the same as the inclination angle of the front cutting edge of the cutting insert 3, the longitudinal direction from the vertical part 10 on the other end side to the one end part of the front cutting edge 4 protruding to the tip side of the cutting edge part 2 Since the protrusion amount can be made smaller than the protrusion amount of the front cutting edge of the cutting inserts of Patent Documents 1 to 3, even if the clearance angle is substantially constant over the entire length of the front cutting edge 4 as in the above embodiment, It is possible to prevent the flank 11 from largely covering the end surface 13 on the one end side, and to secure the area of the flat surface portion 13A perpendicular to the longitudinal direction.

  On the other hand, the other end side of the front cutting edge 4 is a vertical portion 10 and does not extend while the cutting edge continues to retreat, so that the front cutting edge is removed from the flat surface portion 13A perpendicular to the longitudinal direction. Even if the amount of protrusion up to one end of 4 is the same, the amount of protrusion of the front cutting edge 4 on the other end side can be increased to ensure the amount of escape and avoid interference with the work material.

  Further, in the cutting insert of the above embodiment, first, one end portion side of the front cutting edge 4 on the end face 13 is thus formed as a flat surface portion 13A perpendicular to the longitudinal direction, while the other end of the front cutting edge 4 is provided. Since the end face 13 on the part side is formed with a relief portion 13B that recedes in the longitudinal direction with respect to the flat surface portion 13A, the end face that tends to be insufficient with respect to the work material as described above. Thus, a sufficient clearance can be secured on the other end side of the front cutting edge 4 at 13, and interference with the work material can be prevented more reliably.

  Furthermore, the flat surface portion 13A has a larger area as viewed from the direction facing the end surface 13 along the longitudinal direction than the projected portion of the escape portion 13B, and thus forms the escape portion 13B. Even so, the seating stability of the insert body 1 is not impaired. In addition, in the present embodiment, the escape portion 13B is an inclined surface that intersects the flat surface portion 13A at an obtuse angle and gradually recedes toward the other end portion of the front cutting edge 4, so that, for example, one step retreats from the flat surface portion 13A. As compared with the case where the stepped relief portion is formed, the insert main body 1 is not cut out more than necessary, and the cutting edge strength can be prevented from being lowered.

  In addition, if the above-mentioned angle β formed by the inclined surface 13B with respect to the flat surface portion 13A is too small, it is insufficient to secure clearance by providing the escape portion 13B. The other end side of the front cutting edge 4 may be overhanged as described above, and the cutting edge strength may be impaired. For this reason, it is desirable that the angle β formed by the escape portion 13B with respect to the flat surface portion 13A is set in a range of 2 ° to 20 °.

  Secondly, in the cutting insert of the present embodiment, the inclined flat surface portion 11 </ b> A that is a positive flank on the one end portion side of the front cutting edge 4 is a flank 11 on the one end portion side of the front cutting edge 4. And the flat surface portion 13A are formed with an overhang portion 15 that further recedes in the longitudinal direction with respect to the extended surface Q of the positive flank, on the other end side of the front cutting edge 4, Such an overhang portion 15 is not formed, and a part of the inclined flat surface portion 11A and the concave curved surface portion 11B and the vertical flat surface portion 11C of the flank surface 11 which are also positive flank surfaces are directly on the end surface 13. Crossed.

  That is, the overhang portion 15 is formed only on one end portion side of the front cutting edge 4 where the flank 11 largely covers the flat surface portion 13A of the end surface 13, so that the overhang portion 15 is formed on the contact surface of the insert mounting seat. While the abutting flat surface portion 13A can be ensured to be larger, for example, compared to the cutting insert described in Patent Document 1, for example, the flank 11 is cut out so that there are few overhanging portions, and therefore the cutting blade It is possible to prevent the occurrence of damage and the like by further reliably preventing the strength from decreasing. The overhang portion 15 is an inclined surface that gradually recedes with respect to the extended surface Q as it crosses an obtuse angle with the inclined flat surface portion 11A that is the positive flank surface of the flank 11 and moves away from the front cutting edge 4 side. Therefore, the cutting edge strength of the front cutting edge 4 can be ensured even at the one end side that is overhanged.

  As for the overhang portion 15 formed by the inclined surface in this way, if the angle α with respect to the extended surface Q is too small, the area of the flat surface portion 13A cannot be sufficiently secured, whereas if it is too large. There is a risk that the strength of the cutting edge on one end side of the front cutting edge 4 may be impaired. For this reason, it is desirable that the angle α formed by the inclined surface formed by the overhang portion 15 with respect to the extended surface Q is set in a range of 2 ° to 45 °.

  However, in this embodiment, the clearance angle of the front cutting edge 4 is made constant as described above, and the overhang portion is formed on the one end side where the clearance surface 11 largely covers the flat surface portion 13A of the end surface 13 as a result. 15 is formed to ensure a contact area with the contact surface of the insert mounting seat. For example, as in the second embodiment of the present invention shown in FIGS. 4, the clearance angle 11 is changed so as to gradually decrease from one end side toward the other end side, and the flank 11 becomes the full length of the front cutting edge 4 without forming the overhang portion 15 as described above. As a result, the end surface 13 of the insert body 1 may be directly crossed as it is. In the second embodiment, the same reference numerals are assigned to portions common to the first embodiment, and description thereof is omitted.

  That is, in the cutting insert of the second embodiment, the flank 11 is changed from the inclined flat surface portion 11A connected to the linear portion 9A of the inclined portion 9 of the front cutting edge 4 to the concave curved surface portion 11B connected to the curved portion 9B. After that, a twisted surface is formed so that the clearance angle in a cross section parallel to the plane N gradually decreases from one end portion of the front cutting edge 4 to the other end portion until reaching the vertical plane portion 11C connected to the vertical portion 10. Has been. The flank 11 has a substantially constant length in the thickness direction as shown in FIG. 12 when viewed from the longitudinal direction. The flank 11 has a substantially straight line perpendicular to the plane N on the end face 13 of the insert body 1. The crossing ridge line T is directly crossed.

  Accordingly, even in the cutting insert of the second embodiment, the front cutting edge 4 is composed of the inclined portion 9 on one end side and the vertical portion 10 on the other end side. Similar effects can be obtained. And according to this 2nd Embodiment, the flank 11 cross | intersects the end surface 13 of the insert main body 1 directly over the other end part from the one end part of the front cutting edge 4 as mentioned above. Since there is no overhanging portion, the cutting edge strength of the front cutting edge 4 can be more reliably ensured to prevent damage and the like. Moreover, since the escape portion 13B is formed on the end face 13 on the other end side of the front cutting edge 4 where the relief angle becomes small, interference with the work material can be prevented.

  In the first and second embodiments, the end surface 13 including the cutting blade portion 2 including the front cutting blade 4 and the flat surface portion 13A is formed at both end portions of the insert body 1 extending in the axial shape as described above. When the parting process is performed by the front cutting edge 4 at one end, the flat surface part 13A at the other end is in contact with the contact surface of the insert mounting seat. If the inclined portion 9 is provided on the part side and the vertical portion 10 is provided on the other end side, for example, the cutting edge portion 2 is formed only at one end portion in the longitudinal direction of the insert body 1, and the other end portion is pressed against the other end portion. Only the contact portion may be formed. In the above description, the case where the cutting insert according to the present invention is used for parting-off processing has been described. However, it is also possible to use it for grooving of a work material.

1 is a perspective view showing a first embodiment of the present invention. It is the partial top view which looked at the embodiment shown in FIG. 1 from the direction which opposes the rake face 5 perpendicularly to the longitudinal direction of the insert body 1. FIG. 2 is a partial side view of the embodiment shown in FIG. 1 as viewed in a direction facing the side surface 14 from the other end side of the front cutting edge 4 perpendicular to the longitudinal direction of the insert body 1. FIG. 2 is a partial side view of the embodiment shown in FIG. 1 as viewed in a direction perpendicular to the longitudinal direction of the insert body 1 from one end side of the front cutting edge 4 to the side surface 14. FIG. 2 is a partial bottom view of the embodiment shown in FIG. 1 viewed in a direction perpendicular to the longitudinal direction of the insert body 1 and facing the lower surface portion 8. It is the front view which looked at embodiment shown in FIG. 1 in the direction which opposes the end surface 13 along the longitudinal direction of the insert main body 1. FIG. It is a perspective view which shows the 2nd Embodiment of this invention. It is the fragmentary top view which looked at the embodiment shown in FIG. 7 from the direction which opposes the rake face 5 perpendicular | vertical to the longitudinal direction of the insert main body 1. FIG. It is the partial side view which looked at embodiment shown in FIG. 7 in the direction which opposes the side surface 14 from the other end part side of the front cutting blade 4 perpendicularly | vertically to the longitudinal direction of the insert main body 1. FIG. It is the partial side view which looked at the embodiment shown in FIG. 7 in the direction which opposes the side surface 14 from the one end part side of the front cutting edge 4 perpendicularly | vertically to the longitudinal direction of the insert main body 1. FIG. It is the partial bottom view which looked at the embodiment shown in FIG. 7 in the direction which opposes the lower surface part 8 at right angles to the longitudinal direction of the insert main body 1. FIG. It is the front view which looked at embodiment shown in FIG. 7 in the direction which opposes the end surface 13 along the longitudinal direction of the insert main body 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insert body 2 Cutting edge part 3 Horizontal cutting edge 4 Front cutting edge 5 Rake face 6 Corner blade 9 Inclined part 9 of the front cutting edge 4 Linear part 9A of the inclined part 9B Curved part of the inclined part 9 10 Vertical part 11, DESCRIPTION OF SYMBOLS 12 Flank 11A The inclined plane part 11B of the flank 11B The concave curved surface part 11C of the flank 11C The vertical plane part of the flank 11 13 End surface of the insert main body 13A 13A Flat surface part of the end face 13B 13 Flank part of the end face 15 15 Overhang part L Axis θ of the insert body 1 When viewed from the direction facing the rake face 5 perpendicular to the axis L, the angle formed by the inclined portion 9 (straight portion 9A) at one end of the front cutting edge 4 with respect to the vertical portion 10

Claims (4)

  A cutting edge portion having a rake face with a front cutting edge extending in a direction intersecting the longitudinal direction is formed at an end of the insert body extending in the longitudinal direction, and the front cutting edge is opposed to the rake face. As viewed from the direction in which the front cutting edge is moved from one end of the front cutting edge toward the other end, and an inclined portion that is inclined so as to gradually retreat in the longitudinal direction, and from the other end of the front cutting edge toward the one end. And a vertical part extending perpendicularly to the longitudinal direction.   2. The cutting insert according to claim 1, wherein at least the vertical portion side of the inclined portion is formed in a concave curve shape that smoothly contacts the vertical portion when viewed from a direction facing the rake face.   The cutting insert according to claim 1 or 2, wherein at least the one end side of the inclined portion is formed in a straight line when viewed from a direction facing the rake face.   The inclined portion is inclined in a direction intersecting with the vertical portion within a range of 3 ° to 50 ° at one end portion of the front cutting edge as viewed from the direction facing the rake face. The cutting insert as described in any one of Claims 1-3.

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