JP4949890B2 - Cutting insert, throw-away drill and cutting method of work material - Google Patents

Description

  The present invention relates to a cutting insert mounted on a drilling tool for drilling, a throw-away drill using the same, and a method for cutting a work material.

  Conventionally, there is a throw-away drill as a turning tool for drilling holes in a work material such as metal. This drill is provided with an inner blade insert provided with an inner cutting edge portion for cutting the inner peripheral side of the hole bottom and an outer cutting edge portion for cutting the outer peripheral side of the hole bottom at the tip of the drill body having a substantially cylindrical shape. The outer blade insert is detachably mounted and mounted so that the rotation trajectories of the inner cutting blade portion and the outer cutting blade portion cross each other.

  Here, there is a cutting insert provided with the inner cutting edge part and the outer cutting edge part in one insert (for example, refer to Patent Document 1). Such a cutting insert is convenient because it can be used for both the inner blade insert and the outer blade insert.

  FIG. 7 is a schematic plan view showing a conventional cutting insert as described in Patent Document 1. As shown in FIG. FIG. 8 is a schematic explanatory view showing a cutting state by a conventional cutting insert. FIG. 9 is a schematic front view showing a conventional throw-away drill. In addition, the cutting insert shown with a broken line in FIG. 8 has shown the state which the cutting insert shown with a continuous line rotated 180 degree | times.

  As shown in FIG. 7, this cutting insert 100 has a plate shape, specifically, a cutting edge 103 at the intersecting ridge line portion between the upper surface 101 and the side surface 102 of the base body which is an insert body portion having a polygonal plate shape. is doing. The cutting edge 103 has an inner cutting edge portion 104 and an outer cutting edge portion 105 adjacent to the inner cutting edge portion 104. In addition, a breaker groove 107 for processing chips is formed on the upper surface 101 along the cutting edge.

  As shown in FIGS. 8 and 9, such a cutting insert 100 is provided at the tip of one drill body 110 with one of the two cutting inserts 100 serving as an inner blade insert 100 a and the other serving as an outer blade insert 100 b. Installed. Specifically, as shown in FIG. 8, an inner blade insert 100 a is radially inward of the drill body 110 and an outer blade insert 100 b is radially formed of the drill body 110. It is mounted on the outside by changing the mounting direction.

  That is, the inner cutting edge 104 is protruded from the axial front end side of the drill body 110 and the inner cutting edge 104 is formed in the inner cutting edge 104 of the inner blade insert 100a and the outer cutting edge portion 105 of the outer blade insert 100b. The part 104 and the outer cutting edge part 105 are mounted so that the rotation trajectories cross each other.

  As shown in FIG. 9, the inner blade insert 100a and the outer blade insert 100b thus mounted have their upper surfaces 101 oriented in the same rotational direction (arrow A direction). That is, the upper surface 101 of the inner blade insert 100a and the upper surface 101 of the outer blade insert 100b are in a state of being opposite to each other by 180 degrees. Then, the drill body 110 is rotated in the direction of the arrow A around the axis 111 of the drill body 110, and the work material is drilled with the inner blade insert 100a and the outer blade insert 100b.

  Here, the inner cutting edge portion 104 and the outer cutting edge portion 105 are respectively bent portions 106a and 106b that are bent in a convex shape in the top view of the inserts 100a and 100b, the hole bottom inner peripheral corner portions 104a and 105a, It has bottom outer peripheral side corner portions 104b and 105b (see FIG. 8). The bent portions 106a and 106b are for adjusting the balance of cutting resistance.

  With such bent portions 106a and 106b, in a state where the cutting insert 100 is attached to the drill body 110, cutting blades having inclinations opposite to each other with respect to the bottom surface of the hole with the bent portions 106a and 106b as boundaries are located in the cutting blade portion. It is formed. In addition, by having such bent portions 106a and 106b, the inner cutting edge portion 104 and the outer cutting edge portion 105 can have the bent portions 106a and 106b and the hole bottom inner peripheral corner in the top view of the inserts 100a and 100b, respectively. The outer peripheral cutting edge portions 104d and 105d are provided between the inner peripheral cutting edge portions 104c and 105c and the bent portions 106a and 106b and the hole bottom outer peripheral corner portions 104b and 105b between the portions 104a and 105a. Is done.

  However, as shown in FIG. 9, the inner cutting edge portion 104 and the outer cutting edge portion 105 are mounted on the drill main body 110 in a positional relationship parallel to each other in the radial direction. Moreover, the inner peripheral side cutting edge portions 104c and 105c and the outer peripheral side cutting edge portions 104d and 105d are all linear in a side view of the inserts 100a and 100b (that is, linear cutting edge portions). Therefore, the inserts 100a and 100b (that is, the cutting insert 100) generate a force for suppressing the deflection when a specific radial direction along the inner cutting edge portion 104 and the outer cutting edge portion 105 occurs. I can't. For this reason, when bending occurs due to force applied in the lateral direction of the drill main body 110 (in the direction of arrow B in FIGS. 8 and 9) during cutting, the inner cutting edge portion 104 and the outer cutting edge portion 105 slide in that direction. As a result, there is a problem that the drill body 110 is likely to swing and as a result, the dimensional accuracy of the processed hole is deteriorated.

  In order to solve such a problem, either the insert 100a or the insert 100b is disposed on the drill body so as to be inclined rearward with respect to the rotation direction in the front end view, so that the inner cutting edge portion 104 and the outer cutting portion 104 It is conceivable to prevent the blade portion 105 from being parallel in the front end view.

However, in such a case, the force that suppresses the lateral deflection of the drill can be prevented from becoming significantly small in one specific direction, but the force that suppresses the lateral deflection of the drill can be prevented. However, it becomes extremely small in two specific directions. Specifically, in two directions parallel to the inner cutting edge portion and the outer cutting edge portion, the force for suppressing the lateral deflection is reduced. As a result, there is still a problem that the dimensional accuracy of the processed hole is deteriorated.
JP-A-11-235606

  An object of the present invention is to provide a cutting insert, a throw-away drill, and a method for cutting a work material, which are excellent in drilling accuracy.

As a result of intensive studies to solve the above problems, the present inventor has found a solution means having the following configuration, and has completed the present invention.
(1) It has a cutting edge in the intersection ridgeline part of the upper surface and side surface of a base, and the cutting edge is the inner cutting edge part, the outer cutting edge part, and the first located on one end side of the inner cutting edge part. A corner part, and a second corner part located on the other end side of the inner cutting edge part and located on one end side of the outer cutting edge part, and connecting the inner cutting edge part and the outer cutting edge part; A third corner portion located on the other end side of the outer cutting edge portion, and the inner cutting edge portion bends in a convex shape when viewed from above, and the bending portion and the first corner portion. A first inner cutting edge portion located between the second bending edge and the second corner portion, and the outer cutting edge portion is viewed from above. A bent portion bent in a convex shape, a first outer cutting edge portion located between the bent portion and the second corner portion, and a second portion located between the bent portion and the third corner portion. With outer cutting edge A throw-away type cutting insert for a drill, wherein, in a side view, the first inner cutting edge portion of the inner cutting edge portion has a linear shape, and at least the first outer cutting edge portion of the outer cutting edge portion is recessed or A cutting insert having a protruding shape.

(2) The cutting insert according to (1), wherein, in a side view, the first outer cutting edge portion of the outer cutting edge portion has a curved shape that is recessed or protruded.
(3) The lowest point in the thickness direction of the first outer cutting edge portion of the outer cutting edge portion is located on the second corner portion side with respect to the intermediate point in the width direction of the outer cutting edge portion. The cutting insert according to (1) or (2), which is characterized in that
(4) The cutting according to any one of (1) to (3), wherein the second inner cutting edge portion of the inner cutting edge portion has a shape inclined linearly toward the lower surface side of the base body. insert.
(5) The cutting insert according to (4), wherein the inclination angle of the second inner cutting edge portion of the inner cutting edge portion is 5 degrees to 15 degrees.
(6) The cutting insert according to any one of (1) to (5), wherein the third corner portion is positioned higher in the thickness direction than the second corner portion.
(7) The cutting insert according to any one of (1) to (6), wherein a protruding portion that protrudes outward of the base is provided on the third corner portion side of the outer cutting edge portion when viewed from above.

(8) At the tip of the drill body, a cutting insert with an inner cutting edge and a cutting insert with an outer cutting edge are detachable and the rotation trajectory between the inner cutting edge and the outer cutting edge is A throw-away drill mounted so as to cross each other, wherein the cutting insert is the cutting insert according to any one of (1) to (7).
(9) Arranged so that the second outer cutting edge portion of the outer cutting edge portion is inclined rearward in the rotational direction with respect to the first inner cutting edge portion of the inner cutting edge portion in the front end view of the drill body. The throw-away drill according to (8) above, wherein

  (10) A cutting method of cutting a work material using the throw-away drill according to (8) or (9), wherein at least one of the throw-away drill or the work material is rotated, A step of bringing the throw-away drill close to a work material; a step of bringing a cutting edge of the cutting insert into contact with a surface of the work material; and cutting the work material; and the throw away from the work material. And a step of retracting the type drill.

  According to the above (1), (8), (10), in the side view of the cutting insert, the first inner cutting edge portion of the inner cutting edge portion has a linear shape, and at least the first outer cutting edge of the outer cutting edge portion. The shape is a concave or protruding part. Thereby, the cutting blade of the direction different from a linear cutting blade part is formed in the 1st outer cutting blade part of an outer cutting blade part. Therefore, when bending occurs in the lateral direction of the drill body, the force to suppress it is prevented from becoming significantly small in a specific direction (that is, a specific radial direction along the inner and outer cutting edges). can do. As a result, runout of the drill body can be suppressed during cutting, and processing accuracy can be increased. Moreover, even when performing offset machining with a lathe by attaching the insert to the holder so that the linear portion is in the same direction as the offset direction of the lathe by making the first inner cutting edge portion into a linear shape, Since the core height does not change, cutting performance is not deteriorated even in offset machining. Thereby, drilling of various diameters can be handled with a single drill.

According to the above (2), since the first outer cutting edge portion of the outer cutting edge portion has a curved concave shape or a projected shape in a side view, the force applied during cutting is increased in more radial directions. It can disperse | distribute uniformly and can suppress effectively that a drill shakes to a specific radial direction.
According to the above (3), the lowest point in the thickness direction of the first outer cutting edge part of the outer cutting edge part is located closer to the second corner part than the intermediate point in the width direction of the outer cutting edge part. Among the outer cutting edge portions, the second corner portion does not protrude upward, and the cutting edge strength on the second corner portion side can be improved.
According to the above (4) and (5), since the second inner cutting edge portion of the inner cutting edge portion is linearly inclined toward the lower surface side of the insert main body portion, the force from the lateral direction of the drill main body It is possible to further prevent the force that suppresses the deflection generated by the above from being significantly reduced in a specific direction. In addition, since a wider space can be secured on the upper side of the inner cutting edge portion, it is possible to improve chip dischargeability.

According to the above (6), the third corner portion is positioned higher in the thickness direction than the second corner portion, so that the contact of the chips with the inner wall of the machining hole can be reduced, and the chip dischargeability can be reduced. And the accuracy of the finished surface can be improved.
According to said (7), since a protrusion part is provided in the said 3rd corner part side of an outer cutting-blade part, the biting to the work material of an outer cutting-blade part is improved, and the defect | deletion of a cutting blade is suppressed. Can do.
According to said (9), in the front end view of a holder main body, the 2nd outer cutting blade part of the said outer cutting blade part is on the back side of a rotation direction with respect to the 1st inner cutting blade part of the said inner cutting blade part. Since it is arranged so as to be inclined, a part of the force deflected to the radially outer peripheral side generated by the outer cutting blade portion having a recessed or protruded shape can be directed to the radially inner peripheral side, and the outer cutting blade Since excessive deflection to the radially outer peripheral side by the portion can be suppressed, the drilling accuracy is further improved.

  Hereinafter, an embodiment according to a cutting insert and a throw-away drill of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view showing a cutting insert according to the present embodiment. FIG. 2 is a side view showing the throw-away drill according to the present embodiment. FIG. 3 is a partially enlarged side view showing the vicinity of the tip of the throw-away drill according to the present embodiment. FIG. 4 is a schematic explanatory view showing a cutting state by the cutting insert according to the present embodiment. FIG. 5 is a front view showing the throw-away drill according to the present embodiment. FIG. 6 is a partially enlarged perspective view showing the vicinity of the tip of the throw-away drill according to the present embodiment. In addition, in FIG. 4, the insert shown with a broken line has shown the state which the insert shown with a continuous line rotated 180 degree | times.

  As shown in FIG. 1, a cutting insert (hereinafter simply referred to as “insert”) 10 according to the present embodiment has a plate shape, specifically, a base body that is an insert main body portion having a polygonal plate shape. A cutting edge 3 is provided at the intersecting ridge line portion between the upper surface 1 forming the rake face and the side surface 2 forming the flank face. The base is made of, for example, a sintered body such as cemented carbide, cermet, or ceramic coated with a film.

  The film is for improving the wear resistance of the insert 10, and examples of the composition thereof include titanium compounds such as titanium carbide, titanium nitride, and titanium carbonitride, and alumina. Moreover, the film | membrane should just be at least 1 layer, and may be comprised by multiple layers. The substrate is not limited to the one coated with such a film, and a substrate made of a sintered body such as cemented carbide, cermet, ceramics, etc. that does not cover the film may be used.

  A breaker groove 7 for processing chips is formed on the upper surface 1 along the cutting edge 3. Further, a through hole 50 is formed at the center of the upper surface 1. The through hole 50 is a screw hole for fixing the insert 10 to a drill body described later. The insert 10 has a shape that is 180 degrees rotationally symmetric with respect to the central axis of the through hole 50. When one of the cutting blades is worn, the insert 10 is rotated 180 degrees and used. This is economical because the other cutting edge can be used.

  The cutting blade 3 has an inner cutting edge portion 4 that cuts the inner peripheral side of the hole bottom surface and an outer cutting edge portion 5 that is adjacent to the inner cutting edge portion 4 and cuts the outer peripheral side of the hole bottom surface. Further, the outer cutting edge portion 5 is provided with a protruding portion 13 on the other end side (outer peripheral side) in a top view. More specifically, the protruding portion 13 is located on the side of a third corner portion 5b described later, and protrudes outward from the base body in a top view. Thereby, the biting to the work material of the outer cutting edge part 5 can be improved, and the defect | deletion of a cutting edge can be suppressed.

  The protruding portion 13 has curved end portions 13a and 13b. The curved end portions 13a and 13b mean those in the range of 60-160- when the angle formed by the straight line continuous to the curved portion is close to a right angle when viewed from above. Further, by providing a concave cutting edge portion adjacent to the curved end portion 13b and having a configuration in which the step between the protruding portion and the other cutting edge portion is increased, it is possible to divide the chips and to improve the chip dischargeability. Can be improved. Specifically, when the angle formed by the straight line continuous to the curved portion of the curved end portion is set to a smaller value within the above range, that is, an acute angle, the stepped portion becomes larger and the action of dividing chips is enhanced. And chip discharge | emission property can be improved effectively. In addition, the structure of the outer cutting blade part 5 is not limited to the structure which provides the protrusion part 13 in the other end side, The structure which does not provide the protrusion part 13 according to a use may be sufficient.

  Here, the throw-away drill according to the present embodiment is provided with two inserts 10 as described above. That is, as shown in FIGS. 2 to 6, the throw-away drill 30 according to the present embodiment has one drill body 31 with one of the two inserts 10, the inner blade insert 10 a and the other the outer blade insert 10 b. It is attached to the tip of the.

  Specifically, as shown in FIG. 2, the drill main body 31 has a substantially cylindrical shape, and has a shank portion 32 for fixing the drill main body 31 to the machine tool on the rear end side. Moreover, the chip | tip discharge groove | channel 33 for discharging | emitting a chip | tip from the front-end | tip to the shank part 32 side is formed in the front end side of the drill main body 31 spirally along the longitudinal direction. And the pockets 34 and 35 for attaching the inner blade insert 10a and the outer blade insert 10b are provided in the front-end | tip part of the drill main body 31, respectively.

  Each of the pockets 34 and 35 is formed by opening the tip end side in the axial direction of the drill body 31. The pocket 34 is for detachably mounting the inner blade insert 10 a and is formed on the radially inner side of the drill body 31. The pocket 35 is for detachably mounting the outer blade insert 10 b and is formed on the radially outer side of the drill body 31. Further, the pocket 35 is also opened on the outer peripheral side of the hole bottom. Therefore, the inner blade insert 10a that cuts the inner peripheral side of the hole bottom is changed in the mounting direction to the radially inner side of the drill body 31, and the outer blade insert 10b that cuts the outer peripheral side of the hole bottom is changed to the outer radial direction of the drill main body 31. Are mounted in the pockets 34 and 35.

  That is, the inner cutting edge portion 4 is protruded from the axially distal end side of the drill body 31 and the inner cutting edge 4 is protruded from the axially distal end side of the outer blade insert 10b. The rotation trajectories of the part 4 and the outer cutting edge part 5 cross each other and are mounted in the pockets 34 and 35 so as to cover from the axial center 36 to the side surface 37 of the drill body 31. 2 and 3, the mounting screws 51 are inserted into the through holes 50 of the inner blade insert 10a and the outer blade insert 10b, respectively, and the distal ends of the tightening screws 51 are formed in the pockets 34 and 35, as shown in FIGS. This is performed by screwing into a screw hole (not shown).

  As shown in FIGS. 5 and 6, the inner blade insert 10 a and the outer blade insert 10 b thus mounted have their upper surfaces 1 oriented in the same rotational direction (arrow A direction). That is, the upper surface 1 of the inner blade insert 10a and the upper surface 1 of the outer blade insert 10b are in a state of being opposite to each other by 180 degrees. Then, the drill body 31 is rotated in the direction of arrow A about the axis 36 of the drill body 31, and the work material is drilled with the inner blade insert 10a and the outer blade insert 10b (FIGS. 4 and 4). 5).

  Here, the insert 10 (inner blade insert 10a, outer blade insert 10b) according to the present embodiment has cutting blades in directions different from the linear cutting blade portions on the inner cutting blade portion 4 and the outer cutting blade portion 5, respectively. While forming, a part of the inner cutting edge part 4 is made into a linear shape. As shown in FIGS. 4 to 6, the cutting blade 3 according to the present embodiment is a first located on one end side of the inner cutting edge portion 4 in addition to the inner cutting edge portion 4 and the outer cutting edge portion 5 described above. The corner part 4a and the second corner part 4b which is located on the other end side of the inner cutting edge part 4 and located on one end side of the outer cutting edge part 5 and connects the inner cutting edge part 4 and the outer cutting edge part 5 (5a) and a third corner portion 5b located on the other end side of the outer cutting edge portion 5. 4 to 6, 4b and 5a all indicate the second corner portion.

  As shown in FIG. 4, when the insert 10 is mounted on the drill body as an inner blade and an outer blade, in the inner blade insert 10a, the first corner portion 4a is a hole bottom inner peripheral corner portion, a second corner. The portion 4b (5a) is a hole bottom outer peripheral corner portion, and in the outer blade insert 10b, the second corner portion 5a (4b) is a hole bottom inner peripheral corner portion, and the third corner portion 5b is a hole bottom outer peripheral corner portion. It becomes.

  And the inner cutting edge part 4 has the bending part 6a bent in convex shape in the top view. The bent portion 6a is for adjusting the balance of cutting resistance. Further, the inner cutting edge portion 4 has a first inner cutting edge portion 4c positioned between the bent portion 6a and the first corner portion 4a, and between the bent portion 6a and the second corner portion 4b in the top view. And a second inner cutting edge portion 4d. When the insert 10 is mounted on the drill body as the inner blade insert 10a, the first inner cutting edge portion 4c is an inner peripheral cutting edge portion, and the second inner cutting edge portion 4d is an outer peripheral cutting edge portion. Then, in a side view of the inner blade insert 10a, the first inner cutting edge portion 4c has a linear shape (that is, a linear cutting blade portion), and the second inner cutting edge portion 4d is inclined linearly toward the lower surface 8 side of the base. It has a different shape. Thereby, the cutting blade of the direction different from a linear cutting blade part is formed in the inner cutting blade part 4. FIG. In addition, when the first inner cutting edge portion 4c has a linear shape, the insert is attached to the holder so that the linear portion is in the same direction as the offset machining direction of the lathe. However, since the core height does not change, cutting performance is not deteriorated even in offset machining. Thereby, drilling of various diameters can be handled with a single drill.

  When the second inner cutting edge portion 4d is linearly inclined toward the lower surface 8 side of the base body, an angle α formed by an extension line L extending the first inner cutting edge portion 4c and the second inner cutting edge portion 4d. However, it is preferable to incline the second inner cutting edge portion 4d linearly toward the lower surface 8 side so as to be about 5 to 15 degrees (see FIG. 6). Thereby, it can further prevent that the force which suppresses the bending which generate | occur | produces with the force from the horizontal direction of the drill main body 31 becomes remarkably small in a specific direction. In addition, since a wider space can be secured on the upper side of the inner cutting edge portion 4, it is possible to improve the chip discharging property. The shape of the second inner cutting edge portion 4d is not limited to the shape inclined at the angle α, and may be inclined at an arbitrary angle depending on the application.

  On the other hand, the outer cutting edge part 5 includes a bent part 6b bent in a convex shape in a top view, a first outer cutting edge part 5c positioned between the bent part 6b and the second corner part 5a (4b), It has the 2nd outer cutting edge part 5d located between the bending part 6b and the 3rd corner part 5b. When the insert 10 is mounted on the drill body as the outer blade insert 10b, the first outer cutting edge portion 5c is an inner peripheral cutting edge portion, and the second outer cutting blade portion 5d is an outer peripheral cutting edge portion.

  And in the side view of the outer blade insert 10b, the third corner portion 5b side of the second outer cutting blade portion 5d is a linear cutting blade portion, the bent portion 6b side of the second outer cutting blade portion 5d and the first outer cutting edge. The blade portion 5c has a curved shape. As a result, the outer cutting edge portion 5 is formed with a cutting edge in a direction different from the linear cutting edge portion, and the force applied at the time of cutting can be evenly distributed radially in many directions, so that the drill can be specified. Can be effectively prevented from swinging in the radial direction.

  In particular, it is preferable that the bent portion 6b side of the second outer cutting edge portion 5d and the first outer cutting edge portion 5c have a concave shape in an arc shape. (R) is preferably recessed so as to be about 15 mm to 50 mm, but the present invention is not limited to this.

  As described above, the second inner cutting edge portion 4d of the inner cutting edge portion 4 and at least the first outer cutting edge portion 5c of the outer cutting edge portion 5 are each cut in a direction different from the linear cutting edge portion. A blade is formed. Therefore, the force which suppresses the deflection | deviation which generate | occur | produces with the force (arrow B direction in FIG. 4) from the horizontal direction of the drill main body 31 is a specific direction (namely, the inner cutting edge part 4, the outer cutting edge part 5). It is possible to prevent a significant decrease in the radial direction). As a result, the deflection of the drill body 31 can be suppressed during cutting, and the processing accuracy can be increased. Further, the first inner cutting edge portion 4c of the inner cutting edge portion 4 is formed to have a linear shape. As a result, the center height does not change even when performing offset machining on a lathe by attaching the insert to the holder so that the linear portion is in the same direction as the lathe offset machining direction. In this case, the cutting performance is not deteriorated. Thereby, drilling of various diameters can be handled with a single drill.

  On the other hand, if the cutting blade 3 is not configured in the specific shape described above, the above-described effects cannot be achieved. That is, for example, in the side view of the inserts 10a and 10b, the first inner cutting edge portion 4c, the first outer cutting edge portion 5c, the second inner cutting edge portion 4d, and the second outer cutting edge portion 5d are all linear cutting edge portions. When the holder is mounted, all the cutting edge portions of the insert are directed in a specific radial direction, and the force that suppresses the deflection generated by the force from the lateral direction of the drill body 31 is the specific direction. Therefore, it is impossible to prevent the above-described effects from being significantly reduced.

  Here, the reason why the outer peripheral cutting edge 4d of the inner cutting edge 4 is linearly inclined toward the lower surface 8 instead of the arc shape is that the chips generated by the cutting edge are more smoothly cut. This is because it flows toward the pocket and is easily discharged to the outer peripheral side. Moreover, in this embodiment, although the outer cutting blade part 5 illustrated what made the shape dented in one circular arc shape, the outer cutting blade part 5 seems to become a shape dented or protruded. A plurality of linear / inclined cutting edge portions may be used. Even with such a configuration, it is possible to achieve the effect of suppressing the deflection of the drill body during cutting by dispersing the resistance applied during cutting in various directions. In addition, since the space which arises between the scoop surface of an outer blade insert and a drill main body becomes wider, it is more preferable at the point which can aim at the improvement of chip | tip discharge | emission ability. .

  The third corner portion 5b is preferably configured to be positioned higher in the thickness direction than the second corner portion 5a (4b). Thereby, when insert 10a, 10b is mounted | worn with a holder, the height of the both ends of the inner cutting blade part 4 and the outer cutting blade part 5 can be made into a suitable position. Thereby, it can reduce that a chip contacts the inner wall of a processing hole, can improve chip | tip discharge | emission property, and can improve the precision of a finishing surface. Specifically, the first corner portion 4a which is a corner portion located on the outer peripheral side of the insert 10a is more in the thickness direction than the second corner portion 5a (4b) which is a corner portion located on the inner peripheral side of the insert 10a. It will be located at a low level. And the 2nd corner part 5a (4b) which is a corner part located in the inner peripheral side of the insert 10b is located in the lower position in the thickness direction than the 3rd corner part 5b which is a corner part located in the outer peripheral side of the insert 10b. Will be.

  With such a configuration, since the outer peripheral side of the inner cutting edge portion 4 becomes lower, the discharge of chips generated by the inner cutting edge portion 4 becomes smooth, and the chip discharging property is improved. Further, since the outer cutting edge portion 5 has a higher outer peripheral side, the inflection point of the outer cutting blade portion 5 is provided on the inner peripheral side, and the outer cutting edge portion (second outer cutting edge) of the outer cutting blade portion 5 is provided. The strength of the part 5d) can be improved. Therefore, a drill insert with high machining accuracy that can be suitably used for offset machining can be realized while suppressing the deflection of the drill in the lateral direction with an insert using four corners as in this embodiment.

  Moreover, it is preferable that the lowest point in the thickness direction of the first outer cutting edge part 5 c is located on the second corner part 5 a (4 b) side with respect to the intermediate point in the width direction of the outer cutting edge part 5. Thereby, the 2nd corner part 5a (4b) does not protrude upward among the outer cutting edge parts 5, Therefore The cutting edge intensity | strength by the side of the 2nd corner part 5a (4b) can be improved.

  Furthermore, it is preferable that the second outer cutting edge portion 5d is disposed so as to be inclined rearward in the rotational direction with respect to the first inner cutting edge portion 4c in the front end view of the drill body. As a result, a part of the force that is excessively deflected in the radially outer peripheral side generated by the outer cutting blade portion having a recessed or protruded shape can be directed to the radially inner peripheral side. Excessive deflection to the outer peripheral side in the direction can be suppressed, so that the drilling accuracy is further improved.

Finally, a method for cutting a work material according to the present invention using the above-described throw-away drill will be described.
The cutting method of the work material of this invention cuts a work material using the throw away type drill which concerns on this invention mentioned above. Specifically, at least one of a throw-away drill or a work material is rotated to bring the cutting blade close to the work material, and the cutting blade formed on the cutting insert is brought into contact with the surface of the work material. And a step of cutting the work material and a step of retracting the cutting blade from the work material. Thereby, the fracture resistance of a drill improves and it can show the outstanding processing precision. As a result, it is possible to obtain a good finished surface even with a more severe cutting condition or a difficult work material. In addition, stable processing is possible for a long time.

  As mentioned above, although one embodiment concerning the present invention was shown, the present invention is not limited to the above-mentioned embodiment, and it is needless to say that the present invention can be applied to modifications and improvements without departing from the gist of the present invention. Yes. For example, in the insert 10 according to the above-described embodiment, the shape of the outer cutting edge portion 5 is such that the third corner portion 5b side of the second outer cutting edge portion 5d is a linear cutting edge in a side view of the outer blade insert 10b. And the shape of the second outer cutting edge 5d side and the first outer cutting edge 5c is recessed, but the shape of the outer cutting edge according to the present invention is not limited to this. Absent. That is, the shape of the outer cutting edge portion according to the present invention may be a shape in which at least the first outer cutting edge portion of the outer cutting edge portion is recessed or protruded in the side view. Therefore, for example, the entire outer cutting edge portion 5 may be recessed or protruded in an arc shape in the side view.

It is a top view which shows the cutting insert concerning one Embodiment of this invention. It is a side view which shows the throw away type drill concerning one Embodiment of this invention. It is a partial expanded side view which shows the tip part vicinity of the throwaway type drill concerning one Embodiment of this invention. It is a schematic explanatory drawing which shows the cutting state by the cutting insert concerning one Embodiment of this invention. It is a front view which shows the throwaway type drill concerning this embodiment concerning one Embodiment of this invention. It is a partial expansion perspective view which shows the front-end | tip part vicinity of the throw away type drill concerning one Embodiment of this invention. It is a schematic plan view which shows the conventional cutting insert. It is a schematic explanatory drawing which shows the cutting state by the conventional cutting insert. It is a schematic front view which shows the conventional throwaway type drill.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper surface 2 Side surface 3 Cutting blade 4 Inner cutting edge part 4a 1st corner part 4b, 5a 2nd corner part 4c 1st inner cutting edge part 4d 2nd inner cutting edge part 5b 3rd corner part 5c 1st outer cutting edge part 5d Second outer cutting edge portion 5 Outer cutting edge portion 6a, 6b Bending portion 7 Breaker groove 8 Lower surface 10 Cutting insert 10a Inner blade insert 10b Outer blade insert 13 Protruding portion 13a, 13b Curved end portion 30 Throwaway drill 31 Drill Main body 32 Shank portion 33 Chip discharge groove 34, 35 Pocket 36 Axle 37 Side surface 50 Through hole 51 Tightening screw

Claims (9)

It has a cutting edge at the intersection ridge line part of the upper surface and the side surface of the substrate,
The cutting blade includes an inner cutting blade portion, an outer cutting blade portion, a first corner portion positioned on one end side of the inner cutting blade portion, and the other cutting end portion of the inner cutting blade portion. A second corner portion located on one end side of the blade portion and connecting the inner cutting edge portion and the outer cutting edge portion; and a third corner portion located on the other end side of the outer cutting blade portion. And
The inner cutting edge portion includes a bent portion that is bent in a convex shape in a top view, a first inner cutting edge portion positioned between the bent portion and the first corner portion, the bent portion, and the second corner. A second inner cutting edge part located between the two parts,
The outer cutting edge portion includes a bent portion bent in a convex shape in a top view, a first outer cutting edge portion positioned between the bent portion and the second corner portion, the bent portion, and the third corner. A second outer cutting edge portion located between the two, and a throw-away type drill cutting insert having:
In a side view, the first inner cutting edge portion of the inner cutting edge portion has a linear shape, and at least the first outer cutting edge portion of the outer cutting edge portion has a recessed or protruded shape. Cutting insert.   2. The cutting insert according to claim 1, wherein, in a side view, the first outer cutting edge portion of the outer cutting edge portion has a shape that is recessed or protruded in a curved shape.   The lowest point in the thickness direction of the first outer cutting edge portion of the outer cutting edge portion is located on the second corner portion side with respect to the intermediate point in the width direction of the outer cutting edge portion. The cutting insert according to claim 1 or 2.   The cutting insert according to any one of claims 1 to 3, wherein the second inner cutting edge portion of the inner cutting edge portion is linearly inclined toward the lower surface side of the base body.   The cutting insert according to claim 4, wherein an inclination angle of the second inner cutting edge portion of the inner cutting edge portion is 5 degrees to 15 degrees.   The cutting insert according to any one of claims 1 to 5, wherein the third corner portion is positioned higher in the thickness direction than the second corner portion.   The cutting insert according to any one of claims 1 to 6, further comprising a protruding portion protruding outward of the base body on the third corner portion side of the outer cutting edge portion when viewed from above. A cutting insert with an inner cutting edge and a cutting insert with an outer cutting edge are detachably attached to the tip of the drill body and the rotation trajectories of the inner cutting edge and the outer cutting edge cross each other. It is a throw-away type drill mounted as follows,
A throw-away drill, wherein the cutting insert is the cutting insert according to any one of claims 1 to 7. A cutting method of cutting a work material by using the throwaway drill according to claim 8 Symbol mounting,
Rotating at least one of the throwaway drill or the work material, and bringing the throwaway drill in proximity to the work material;
Contacting the cutting edge of the cutting insert with the surface of the work material, and cutting the work material;
Retracting the throwaway drill from the work material;
A cutting method comprising:

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