JP5383149B2 - Drill and cutting method - Google Patents

Description

  The present invention relates to a drill and a cutting insert used for the drill.

  Conventionally, there is a throw-away drill as a drilling tool for drilling a workpiece such as metal. This drill has a first insert provided with a cutting edge (outer blade) for cutting the outer peripheral side of the hole bottom, and a cutting blade (inner blade for cutting the inner peripheral side of the hole bottom) at the tip of a drill holder having a substantially cylindrical shape. ) Is detachably mounted. The second insert is arranged on the axis side of the drill holder, and the first insert is arranged on the outer peripheral side of the drill holder. At this time, the rotation locus of the cutting blade of the second insert and the rotation locus of the cutting blade of the first insert intersect each other.

  Patent Document 1 discloses a drill insert having an inner blade and an outer blade and having a breaker groove formed along each of the cutting blades. In the drill insert, the rising wall of the breaker groove along the inner blade gradually increases or decreases from one of the inner blades toward the other, and the rising wall of the breaker groove along the outer blade extends from one of the outer blades. It is formed so as to gradually become higher or lower toward the other side.

In the insert having such a configuration, there has been a problem that, in cutting of a work material having a high ductility, the generated chips get over the breaker groove without being curled and are entangled with the drill holder.
JP 2003-62712 A

  An object of the present invention is to provide a drill having excellent chip dischargeability and a cutting insert used for the drill.

One embodiment of the drill according to the present invention is a drill holder having a first insert pocket formed on the outer peripheral side of the tip portion, and a second insert pocket formed on the center axis side of the tip portion, A first cutting insert attached to the first insert pocket for cutting the outer peripheral side of the hole bottom; and a second cutting insert attached to the second insert pocket for cutting the inner peripheral side of the hole bottom. the first cutting insert, and a top surface having a first side adjacent to the corner portion and the corner portion, and a first cutting edge which is formed to extend from the front Symbol corner along the first side, of the upper surface A first rake face along the first cutting edge, and the first cutting edge is bent so that the center protrudes outward in a top view, and one end close to the corner portion, The corner Has to the other end was, spaced from, at least partially, with protrudes from the outer circumferential surface and the front end surface of the drill holder along the front end surface of the drill holder, the corners the drill holder One end of the first cutting edge is disposed closest to the outer peripheral surface of the drill holder among the first cutting edges so that the first rake face is located on the outer peripheral end of the first cutting edge. A first region that is located on one end side of the first cutting edge with respect to the bending point and a rake angle is substantially constant, and is located on the other end side of the first cutting edge with respect to the bending point of the first cutting edge. to with rake angle anda larger second region closer to the other end, the rake angle of the first rake face at the other end of said first cutting edge, said at one end of said first cutting edge Be larger than the rake angle of the first rake face And features.

  Furthermore, one embodiment of a cutting method of a work material according to the present invention is a method of cutting a work material, the step of rotating at least one of the work material and the drill described above, A step of bringing the first cutting edge close to the work material; a step of bringing the first cutting edge into contact with a surface of the work material; and cutting the work material; and the first cutting edge of the work material. And a step of separating from the material.

According to drill according to the present invention, machining the wall surface of the thickness at the inner periphery side of the chip generated by the first cutting edge, and thinner than the thickness of the chips on the outer peripheral side, chips can workpiece When it touches, chip can be bent stably. As a result, the chips are easily divided in the length direction of the chips, and the chips can be prevented from being entangled with the holder, thereby improving the chip dischargeability.

  Moreover, according to the cutting method of the work material which concerns on this invention, since the drill which suppresses that a chip | tip gets entangled with a holder and exhibits the outstanding chip | tip discharge | emission property is used, a workpiece with high finishing surface accuracy is obtained. be able to.

<Drill>
The drill 10 by 1st embodiment which concerns on this invention is demonstrated in detail using FIG. 1 thru | or FIG.

  1 is a side view of the drill 10, FIG. 2 is an enlarged view of a main part of FIG. 1, and FIG. 3 is a front view of FIG.

  As shown in FIG. 1, the drill 10 has a drill holder 11 and two cutting inserts 1.

  Specifically, the drill holder 11 of the present embodiment has a substantially cylindrical shape. The rear end side of the drill holder 11 is fixed to a machine tool or a connection member. And the drill holder 11 has the 1st insert pocket 12A formed in the outer peripheral side of a front-end | tip part, and the 2nd insert pocket 12B formed in the central-axis side of a front-end | tip part.

  As shown in FIGS. 2 and 3, the first insert pocket 12 </ b> A and the second insert pocket 12 </ b> B are both open at the distal end side in the axial direction of the drill holder 11. The first insert pocket 12A is also opened on the radially outer peripheral side. The first insert pocket 12 </ b> A and the second insert pocket 12 </ b> B are located on the opposite sides in the radial direction with respect to the axis L of the drill holder 11.

  The drill holder 11 is provided with two flutes 13 (13A, 13B) that serve as a passage until chips are discharged outward from the drill 10. The flute 13A communicates with the first insert pocket 12A, and the flute 13B communicates with the second insert pocket 12B. In the present embodiment, the flutes 13 </ b> A and 13 </ b> B are formed in the drill holder 11 in a spiral shape as concave grooves.

  The first insert 1A is mounted on the first insert pocket 12A, and the second insert 1B is mounted on the second insert pocket 12B. Specifically, each insert 1 </ b> A, 1 </ b> B is attached to the corresponding insert pocket (12 </ b> A, 12 </ b> B) by the screw member 14.

  The first insert 1A is an insert having a cutting edge (outer blade) that performs cutting on the outer peripheral side of the hole bottom. And the 2nd insert 1B is an insert with the cutting blade (inner blade) which performs the cutting of a hole bottom inner peripheral side.

  The first insert 1 </ b> A is mounted in the first insert pocket 12 </ b> A so that at least a part of the outer blade protrudes from the tip of the drill holder 11. And 2nd insert 1B is mounted | worn with the 2nd insert pocket 12B so that at least one part of an inner blade may protrude from the front-end | tip part of the drill holder 11. FIG. At this time, the rotation trajectory of the outer blade and the rotation trajectory of the inner blade on the distal end side intersect each other in an arbitrary cross section passing through the axis L of the holder 11. And the 1st insert 1A and the 2nd insert 1B are each arranged so that the rotation locus of an outer blade and the rotation locus of an inner blade may cover from the central axis of drill holder 11 to an outer peripheral surface. In FIG. 2, the position of the 2nd insert 1B at the time of rotating the 2nd insert 1B 180 degree | times centering on the axis line L of the drill holder 11 is shown with the dotted line.

  The first insert 1A and the second insert 1B mounted in this way are arranged so that the upper surfaces of both faces in the same rotational direction. That is, the upper surface of the first insert 1A and the upper surface of the second insert 1B are in a state in which they are directed in opposite directions by 180 degrees. Then, the drill holder 11 is rotated around the axis L of the drill holder 11, and the workpiece is drilled with the first insert 1A and the second insert 1B.

  In the present embodiment, both the first insert 1A and the second insert 1B are mounted on the drill holder 11 so as to have a positive axial rake.

In the present embodiment, the inserts having the same shape are mounted in different positions (changing the mounting direction) in each of the first insert pocket 12A and the second insert pocket 12B. That is, the 1st insert 1A and the 2nd insert 1B are inserts which make the same shape which has an outer blade and an inner blade. When the insert is used as the first insert 1 </ b> A, the outer blade is disposed so as to protrude from the tip of the drill holder 11. On the other hand, when the insert is used as the second insert 1 </ b> B, the inner blade is arranged so as to protrude from the tip of the drill holder 11. Thus, the insert of this embodiment is excellent in terms of storage and management of the insert or cost because one type of insert can be used as both the first insert 1A and the second insert 1B.
<Cutting insert>
(First embodiment)
Hereinafter, an insert 1 according to an embodiment of the present invention mounted on a drill according to the present embodiment will be described in detail with reference to FIGS. 4 and 5.

  4A is a top view of the insert 1, FIG. 4B is a side view of one side (short side view), FIG. 4C is another side view (long side view), and FIG. 4, (a) AA sectional view, (b) BB sectional view, (c) CC sectional view, (d) DD sectional view, (e) EE sectional view. .

  As shown in FIG. 4, the insert 1 according to the present embodiment has a plate shape, specifically, a polygonal plate shape. The insert 1 is made of, for example, a sintered body such as cemented carbide, cermet, ceramic, or the like, and the sintered body covered with a film.

  The insert 1 has an upper surface 2, a lower surface 3, and a side surface 4. The upper surface 2 has a corner part c and a first side 21.

  The insert 1 further has a first cutting edge 5 and a first rake face 7. The first cutting edge 5 is formed extending from the corner portion c along the first side 21. The first cutting edge 5 is located at least at a part of the intersection with the side surface 4.

  The first cutting edge 5 is a cutting edge located on the outer peripheral side of the drill holder 11 when the insert 1 is mounted on the drill holder 11 as the first insert 1A. That is, as shown in FIGS. 2 and 3, the first cutting edge 5 is arranged so that at least a part thereof protrudes from the tip surface and the outer peripheral surface of the drill holder 11. At this time, the corner portion c is located at the outer peripheral end of the drill holder 11. By arrange | positioning in this way, the 1st cutting blade 5 functions as a cutting blade (outer blade) which cuts the hole bottom outer peripheral side.

  The first rake face 7 is an area along the first cutting edge 5 in the upper face 2. In addition, the area | region which follows the 1st cutting blade 5 among the side surfaces 4 functions as a flank. The lower surface 3 functions as a seating surface that comes into contact with an insert pocket formed in the drill holder 11.

  FIG. 5A is a cross-sectional view taken along the line AA of FIG. 4 as described above, and is a cross-sectional view of the outer peripheral side end portion of the first cutting blade 5. Specifically, it is a cross-sectional view that passes through one end p <b> 1 of the first cutting edge 5 and is substantially perpendicular to the lower surface 3. FIG. 5E is a cross-sectional view taken along the line E-E in FIG. 4, and is a cross-sectional view of the inner peripheral side end portion of the first cutting edge 5. Specifically, it is a cross-sectional view that passes through the other end p <b> 2 of the first cutting edge 5 and is substantially perpendicular to the lower surface 3.

  Here, the insert 1 of the present embodiment is characterized by satisfying the following relationship.

  5A and 5E, the rake angle of the first rake face 7 at one end p1 of the first cutting edge 5 is θ1, and the first rake face 7 at the other end p2 of the first cutting edge 5 is. When the rake angle is θ2, θ1 <θ2.

  Thereby, the thickness of the chip | tip produced | generated with the 1st cutting blade 5 can be made thinner in the inner peripheral side rather than the outer peripheral side. The chip having such a shape is curled and inverted by the first rake face 7 and is stably bent when it comes into contact with the machining wall surface of the work material.

  Hereinafter, the bending of chips in the insert 1 of this embodiment will be described in detail.

  First, as described above, chips are bent when the chips come into contact with the processed wall surface of the work material. The part of the chip that comes into contact with the machining wall surface of the workpiece first is the outer peripheral side of the chip that has the highest rotational speed and is closest to the machining wall surface of the workpiece. Therefore, the starting point of chip folding is the outer peripheral side of the chip.

  Moreover, in this embodiment, the chip | tip produced | generated with the 1st blade 5 makes the shape where the thickness of the chip | tip of an inner peripheral side is thinner than the thickness of the chip | tip of an outer peripheral side as mentioned above. Thereby, the chip | tip produced | generated with the 1st blade 5 of this embodiment becomes easy to extend the inner peripheral side in the bending part of a chip | tip.

  Therefore, the chips generated by the first blade 5 have a stable shape. This stabilizes the chip discharge direction. That is, the chips having a stable shape are smoothly discharged to the outside of the drill 10 along the flute 13 having a helically twisted shape. As a result, the resistance between the chips and the inner wall surface of the flute 13 is reduced, and the chips can be prevented from being entangled with the drill holder 11.

  Further, the chip whose inner peripheral side extends in this way has a shape in which the macro shape is more straight and extended. For this reason, the chips are easily divided in the length direction of the chips due to contact with the inner wall surface of the flute having a twisted shape, a centrifugal force when coming out from the surface of the work material, or the like. As a result, the chip dischargeability can be further improved.

  Such an improvement in chip dischargeability by the first blade 5 of the present embodiment can be suitably obtained also in a cutting work of a work material rich in ductility, for example, a work material such as stainless steel.

  In addition, the inner peripheral side of a chip here is a part located in the axis line L side of the drill holder 11 when a chip is produced | generated.

  The rake angle θ referred to here is, as shown in FIG. 5, the first rake face 7 relative to the lower face 3 in the cross section of the insert 1 perpendicular to the first cutting edge 5 and perpendicular to the lower face 3 as viewed from above. The inclination angle. When the 1st rake face 7 is comprised by the curved surface, let the inclination angle with respect to the lower surface 3 of the tangent in the edge part by the side of the 1st cutting blade 5 be the rake angle (theta).

  Furthermore, in the present embodiment, the rake angle θ of the first rake face 7 gradually increases as it goes from one end p1 to the other end p2. That is, as shown in FIG. 5, the rake angle in the AA cross section that passes through one end p1 is θ1, the rake angle in the EE cross section that passes through the other end p2 is θ2, and a bending point p3 described later is set. The rake angle in the CC cross section, which is a cross section passing through, is θ3, the rake angle in the BB cross section, which is a cross section passing through an arbitrary position between the one end p1 and the bending store p3, is θ4, the bending point p3 and the other end p2 A rake angle in a DD section which is a section passing through an arbitrary position between and is .theta.5. At this time, in the present embodiment, the rake angles θ1 to θ5 in the respective sectional views passing through the first cutting edge 5 of the first rake face 7 are θ1 <θ4 <θ3 <θ5 <θ2.

  As a result, it is possible to improve the above-described chip discharge property while suppressing the sharpening of the cutting edge strength. For this reason, it is possible to suppress the chipping of the cutting edge and the chipping of the holder due to chip clogging, and the tool life of the insert can be improved.

  In the present embodiment, θ1 to θ5 are θ1 = 10 degrees, θ4 = 12 degrees, θ3 = 15 degrees, θ5 = 18, and θ2 = 20 degrees, respectively.

  Furthermore, in the present embodiment, the first cutting edge 5 is provided with the center bent outward in a top view. That is, the first cutting edge 5 includes two cutting edge portions having different inclination angles with respect to the bending point p3. In the present embodiment, the angle formed by the two cutting blade portions on the upper surface is an obtuse angle. Such a cutting edge shape can reduce the impact when the largest impact is applied to the insert 1, that is, when the first cutting edge comes into contact with the work material. Therefore, variations in the machining diameter can be suppressed and the tool life of the insert 1 can be improved.

  In such a cutting edge shape, the increasing rate of the rake angle θ of the first rake face 7 on the other end p2 side of the first cutting edge 5 from the bending point p3 of the first cutting edge 5 is the first cutting edge 5. It is desirable that the rate of increase of the rake angle θ of the first rake face 7 on the one end p1 side of the first cutting edge 5 is larger than the bending point p3. With such a configuration, the chip thickness on the inner peripheral side away from the outer peripheral side, which is the starting point of chip folding, becomes thinner. Therefore, since the shear layer of the chips is bent by forming the bent shape, even if the chips are harder to be bent than the linear cutting blade, the chips are stably bent to the inner peripheral side. Therefore, the shape of the chip can be stabilized and the volume of the chip can be reduced. As a result, the impact when the first cutting edge comes into contact with the work material is reduced to suppress variation in the machining diameter, and the chip discharge performance is improved.

  Moreover, the insert 1 of this embodiment also has the 2nd cutting blade 8 which functions as an inner blade in addition to the 1st cutting blade 5 which functions as an outer blade, as mentioned above. As shown in FIGS. 4 and 5, the second cutting edge 8 is provided along the second side 22 of the upper surface 2.

  The second cutting edge 8 is a cutting edge located on the axis line side of the drill holder 11 when the insert 1 is mounted on the drill holder 11 as the second insert 1B. That is, as shown in FIGS. 2 and 3, at least a part of the second cutting edge 8 protrudes from the tip surface of the drill holder 11, and is closer to the axis of the drill holder 11 than the first cutting edge 5. Is arranged. By being arranged in this way, the second cutting blade 8 functions as a cutting blade (inner blade) for cutting the inner peripheral side of the hole bottom.

  In the present embodiment, the through hole 6 through which the screw member 14 is inserted when the drill holder 11 is mounted is provided from the upper surface 2 to the lower surface 3. The insert 1 has a 180-degree rotationally symmetric shape with respect to the central axis of the through hole 6. Therefore, the insert 1 of this embodiment has two first cutting edges 5 and two second cutting edges 8 each.

  As described above, the insert 1 according to this embodiment can exhibit excellent chip discharge performance. Therefore, a drill is formed by mounting one insert 1 in the first insert pocket 12A as the first insert 1A in the drill holder 11 and mounting one insert 1 in the second insert pocket 12B as the second insert 1B. 1 can suppress the clogging of chips in the flutes 13A and 13B. Therefore, it is possible to prevent the chips from damaging the work material or damaging the drill holder 11. As a result, machining accuracy and tool life can be improved.

(Second embodiment)
Hereinafter, insert 1 'by 2nd embodiment which concerns on this invention is demonstrated in detail using FIG. 6 and FIG. 6A is a top view of the insert 1 ′, FIG. 6B is a side view of one side (short side view), and FIG. 6C is another side view (long side view). (A) AA sectional view, (b) BB sectional view, (c) CC sectional view, (d) DD sectional view, (e) EE sectional view of FIG. is there. In addition, about the structure similar to the insert 1 of 1st embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The insert 1 ′ of the present embodiment, like the insert 1, can be used as both the first insert 1 </ b> A and the second insert 1 </ b> B. Both two cutting edges 8 are provided.

  In this embodiment, unlike the insert 1 in the first embodiment, the configuration of the first rake face 7 is different. Specifically, in the present embodiment, the first rake face 7 ′ has a first region 71 and a second region 72. The first region 71 is located on one end p1 side and has a constant rake angle θ. The second region 72 is positioned closer to the other end p2 than the first region 71, and increases as the rake angle θ approaches the other end p2.

  Specifically, as shown in FIG. 6, the rake angles θ1 to θ5 in each cross section are θ1 = θ4 = θ3 <θ5 <θ2 in the present embodiment. Here, θ1 to θ5 are rake angles in the same cross section as in the first embodiment described above. With such a configuration, it is possible to maintain the strength of the cutting edge portion that generates the outer peripheral side of the chip that is easily bent, and to reduce the thickness of the inner peripheral side of the chip that is difficult to be bent.

  In particular, as described in the first embodiment, the present embodiment also has a bent cutting edge shape in a top view. In the case of such a cutting edge shape, it is folded along a line on the outer peripheral side in a sheared layer of bent chips. In the form having such a chip folding mechanism, by satisfying the relationship of the rake angles θ1 to 5 described above, the cutting edge strength is increased on the outer peripheral side that is easy to bend because the chip folding line is along the shear layer. Can be improved. At the same time, on the inner peripheral side where the chip fold line does not follow the shear layer, the rake angle can be increased to reduce the thickness of the generated chip. As a result, it is possible to combine the improvement of the cutting edge strength and the improvement of chip discharge.

  In the present embodiment, θ1 to θ5 are θ1 = θ4 = θ3 = 12 degrees, θ5 = 18 degrees, and θ2 = 20 degrees, respectively.

  In the present embodiment as well, the first cutting edge 5 has a bent shape so that the center protrudes outward in a top view, as in the first embodiment. In the insert 1 ′ having such a bending point p3, the first region 71 is located on the one end p1 side with respect to the bending point p3, and the second region 72 is located on the other end p2 side with respect to the bending point p3. ing. In the present embodiment, the first region 71 is a region from one end p1 to the bending point p3, and the second region 72 is a region from the bending point p3 to the other end p2.

  With such a configuration, even with the first cutting edge 5 having a bent cutting edge shape, chips can be stably bent from the outer peripheral side to the inner peripheral side. Therefore, the chip dischargeability can be improved.

(Third embodiment)
Hereinafter, an insert 1 ″ according to a third embodiment of the present invention will be described in detail with reference to FIGS. 8 and 9. FIG. 8 shows (a) a top view of the insert 1 ″ and (b) one of the drawings. FIG. 9 is a side view (: short-side side view), (c) another side view (: long-side side view), and FIG. 9 is (a) AA cross-sectional view of FIG. 8, (b) B- B sectional drawing, (c) CC sectional drawing, (d) DD sectional drawing, (e) EE sectional drawing. In addition, about the structure similar to the insert 1 of 1st embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The insert 1 ″ of the present embodiment is the same as the insert 1 in that the first cutting edge 5 serving as the outer blade and the first cutting blade serving as the inner blade are used as the first insert 1A and the second insert 1B. Both two cutting edges 8 are provided.

  In the insert 1 ″ of the present embodiment, a first land 9 extending from the first cutting edge 5 toward the inside of the upper surface 2 is provided along the first cutting edge 5. And FIG. 8 and FIG. As shown in FIG. 9, the inclination angle φ <b> 2 with respect to the lower surface 3 of the first land 9 at the other end p <b> 2 of the first cutting edge 5 is larger than the land angle φ <b> 1 of the first land 9 at one end p <b> 1 of the first cutting edge 5.

  Even with such a configuration, the thickness of the chip on the inner peripheral side can be made thinner than the thickness of the chip on the outer peripheral side. Therefore, the inner peripheral side of the chip that is difficult to be bent can be stably bent. As a result, the shape of the chip to be discharged is stabilized, the volume of the chip can be reduced, and the chip can be discharged.

  Here, for the sake of convenience, the inclination angle of the first land 9 with respect to the lower surface 3 is hereinafter referred to as a land angle φ.

  Note that the land angle φ here is also similar to the rake angle θ described above, as shown in FIG. 9, in the cross section of the insert 1 ″ perpendicular to the first cutting edge 5 and perpendicular to the lower surface 3 as viewed from above. The inclination angle of the first land 9 with respect to the lower surface 3. When the first land 9 is formed of a curved surface, the inclination angle with respect to the lower surface 3 of the tangent at the end on the first cutting edge 5 side is the land angle φ. To do.

  In addition, it is desirable that the land angle φ is gradually increased from the one end p1 toward the other end p2. Specifically, as shown in FIG. 9, it is desirable that the land angles φ1 to φ5 in each cross section satisfy φ1 <φ4 <φ3 <φ5 <φ2 as in the present embodiment. With such a configuration, the inner peripheral thickness of the generated chips can be made smaller than the outer peripheral thickness. Therefore, the chips can be bent stably, and the chip discharge performance can be improved. Note that. By setting the land angles φ1 to 5 to be in the above relationship, cutting heat generated at the time of contact with the work material can be suppressed. Therefore, when the work material is a material that causes work hardening, work hardening on the inner peripheral side of the chip can be reduced. As a result, the inner peripheral side of the chip can be more easily bent.

  Furthermore, in the present embodiment, as shown in FIG. 9A, the land angle φ1 at one end p1 is 0 degree. With such a configuration, the first cutting that is likely to receive a large impact during cutting can improve the cutting edge strength of one end p1 (outer end portion) of 5. Therefore, the chip dischargeability described above can be improved while suppressing the loss of the first cutting edge 5.

  In the present embodiment, φ2 to φ5 are φ4 = 3 degrees, φ3 = 5 degrees, φ5 = 8 degrees, and φ2 = 10 degrees, respectively.

  As in the case of the rake angle θ described above, there may be a region where the land angle is constant between the one end p1 and the other end p2.

(Fourth embodiment)
Hereinafter, an insert 1 ″ ′ according to a fourth embodiment of the present invention will be described in detail with reference to FIGS. 10 and 11. FIG. 10 shows (a) a top view of the insert 1 ″ ′, and (b). FIG. 11 is a side view of one side (: side view of short side), (c) another side view (: side view of long side), and FIG. 11 is a cross-sectional view of FIG. It is BB sectional drawing, (c) CC sectional drawing, (d) DD sectional drawing, (e) EE sectional drawing. In addition, about the structure similar to the insert 1 of 1st embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  The insert 1 ″ ′ of the present embodiment, like the insert 1, becomes the first cutting edge 5 serving as the outer blade and the inner blade so that it can be used as the first insert 1A and also as the second insert 1B. Both the second cutting edge 8 and the second cutting edge 8 are provided.

  In the insert 1 ″ ′ of the present embodiment, a first land 9 extending from the first cutting edge 5 toward the inside of the upper surface 2 is provided along the first cutting edge 5.

  10 and 11, the width W1 of the first land 9 at the other end p2 of the first cutting edge 5 is smaller than the width W2 of the first land 9 at one end p1 of the first cutting edge 5. . Even with such a configuration, the thickness of the chip on the inner peripheral side can be made thinner than the thickness of the chip on the outer peripheral side. Therefore, the inner peripheral side of the chip that is difficult to be bent can be stably bent. As a result, the shape of the chip to be discharged is stabilized, the volume of the chip can be reduced, and the chip can be discharged.

  Note that the width W1 of the first land 9 here is a dimension of the first land 9 in a direction perpendicular to the first cutting edge 5 in a top view, as shown in FIG.

  In the present embodiment, the land width W is constant from one end p1 to the bending point p3, and from the bending point p3 to the other end p2, the land width W increases from the bending point p3 to the other end p2. , Gradually decreases from one end p1 to the other end p2. Specifically, as shown in FIG. 11, land widths W1 to W5 in each cross section are W1 = W4 = W3> W5> W2. With such a configuration, the thickness of the inner peripheral side of the chip corresponding to the portion that is difficult to be bent from the bending point p3 to the other end p2 can be made smaller than the thickness of the outer peripheral side. Therefore, it is possible to stably fold the chips while maintaining the cutting edge strength, and to improve the chip dischargeability. Similarly to the land angle φ, when the land width satisfies the above relationship, when the work material is a material that causes work hardening, work hardening on the inner peripheral side of the chip can be reduced. As a result, the inner peripheral side of the chip can be more easily bent.

  In the present embodiment, W1 to W5 are W1 = W4 = W3 = 0.1 mm, W5 = 0.07 mm, and W2 = 0.06 mm, respectively.

  As in the case of the rake angle θ and the land angle φ described above, there is no region in which the land width W is constant between one end p1 and the other end p2, that is, from one end p1 to the other end p2. The land width W may be gradually reduced.

  As described above, as the embodiment according to the present invention, the form in which any one of the rake angle θ, the land angle φ, and the land width W has a characteristic configuration has been illustrated. The embodiment according to the present invention is not limited to this, and may be a combination of the configurations of the plurality of embodiments, such as a configuration in which both the rake angle θ and the land angle φ are configured as described above.

  In addition, as described above, in the drill having a configuration in which the inner blade insert and the outer blade insert are mounted on the drill holder as in the present embodiment, the first cutting functioning as the outer blade as described above. The rotation trajectories of the blade and the second cutting blade functioning as the inner blade intersect. Therefore, the rake angle of the first rake face at the other end of the first cutting edge is larger than the rake angle of the first rake face at one end of the first cutting edge means that the inner circumference of the cutting edge portion functioning as an outer cutter It is sufficient that the rake angle is larger at the side end portion than at the outer peripheral side end portion. That is, the other end of the first cutting edge is an outer peripheral end of the cutting edge that substantially functions as an outer cutting edge, and does not have to be positioned at one corner of the upper surface.

  The method of changing each angle and width is not limited to the above-described form, and any configuration may be used as long as the thickness of the inner peripheral chip is smaller than the thickness of the outer peripheral chip.

  Further, in the above-described embodiment, the first cutting blade 5 is exemplified as a form having a bent shape in the top view, but is not limited thereto, and the first cutting blade 5 has a linear form in the top view. It doesn't matter.

  Furthermore, in the above-described embodiment, the form in which the breaker groove 15 is formed along the first cutting edge 5 is illustrated. However, the present invention is not limited to this, and the same surface as the first rake face 7 is the upper surface 2. It may be a form extending to the center.

In addition, when the breaker groove is formed, it is desirable to form a concave shape with respect to the first cutting edge 5 and a substantially arc shape in a top view. In particular, it is desirable that the portion of the breaker groove 15 having a substantially arc shape is provided at a position corresponding to the inner peripheral side of the first cutting edge 5 configured to reduce the thickness of the chip.
When the breaker groove 15 has such a shape, the chip can be curled so that the cross-sectional shape on the inner peripheral side of the chip becomes a curved shape. Thereby, the cross-sectional shape of the generated chips can be made concave. Such a chip having a concave cross-sectional shape easily breaks the inner peripheral side when the chip is bent as described above. Chips whose inner peripheral side is torn are more easily made to conform to the flute shape. Therefore, the chips are discharged further smoothly out of the drill 10 along the flute 13 having a helically twisted shape. As a result, the resistance between the chips and the inner wall surface of the flute 13 is reduced, and the effect of suppressing the chips from being entangled with the drill holder 11 is enhanced.

Furthermore, as an embodiment described above, a throw-away type drill in which an insert is mounted on a drill holder has been exemplified, but the present invention is not limited to this, and has a configuration of a rake angle, a land angle, and a land width as described above. A solid drill may be used.
<Cutting method of work material>
Finally, an embodiment of a cutting method for a work material according to the present invention will be described in detail with reference to FIGS. 12A to 12C, taking the case of using the drill 10 as an example.

  The cutting method of the work material concerning this embodiment has the following processes (i)-(iv).

(I) As shown in FIG. 12A, the drill 10 is rotated in the direction indicated by the arrow H around the axis L of the holder 31. (ii) As shown in FIG. To move the first cutting edge 5 of the first insert 1A of the drill 10 and the second cutting edge 8 of the second insert 1B close to the work material 60, respectively (iii) FIG. As shown in (b), the drill 10 is further moved in the direction indicated by the arrow F, and at least a part of the first cutting edge 5 and the second cutting edge 8 of the drill 10 is brought into contact with the surface of the work material 60. Cutting the workpiece 60 (hole machining)
(Iv) As shown in FIG. 12 (c), the drill 10 is moved in the direction indicated by the arrow G, and the first cutting edge 5 and the second cutting edge 8 are separated from the work material 60. 10 is equipped with the above-described insert 1. Therefore, the cutting method of this embodiment can suppress that chips are entangled with the drill holder 11 during the cutting process. Therefore, it is possible to suppress the entangled chips from blocking the flute serving as the chip discharge passage and preventing the chips from being discharged. Thereby, it can suppress that a chip | tip clogs and damages the process wall surface of a workpiece. As a result, it is possible to realize cutting with high finished surface accuracy.

In the step (i), at least one of the drill 10 and the work material 60 may be rotated. In the step (ii), each cutting blade and the work material 60 may be relatively close to each other. For example, the work material 60 may be close to each cutting blade. Similarly, in the step (iv), the work material 60 and each cutting edge only need to be relatively distant from each other. For example, the work material 60 may be kept away from each cutting edge. In the case of continuing the cutting process, the state in which the drill 10 and / or the work material 60 is rotated and the cutting blades of the drill 10 are brought into contact with different portions of the work material 60 may be repeated. . When the cutting blade used is worn, the insert 1 may be rotated 180 degrees with respect to the central axis of the through hole 6 and an unused cutting blade may be used.

  As mentioned above, although some embodiment concerning this invention was shown, this invention is not limited to embodiment mentioned above, It can apply also to what was changed and improved in the range which does not deviate from the summary of this invention. Needless to say.

1 is a side view of a drill 10 according to a first embodiment of the present invention. It is a principal part enlarged view of FIG. It is a front view of the drill 10 of FIG. (A) top view of cutting insert 1 by a 1st embodiment concerning the present invention, (b) one side view (: short side side view), (c) other side view (: long side side view) ). It is (a) AA sectional drawing of FIG. 4, (b) BB sectional drawing, (c) CC sectional drawing, (d) DD sectional drawing, (e) EE sectional drawing. (A) Top view of cutting insert 1 'by 2nd Embodiment which concerns on this invention, (b) One side view (: Short side side view), (c) Other side view (: Long side side surface) Figure). 7A is a cross-sectional view taken along line AA, FIG. 6B is a cross-sectional view taken along line BB, FIG. 6C is a cross-sectional view taken along line CC, FIG. 6D is a cross-sectional view taken along line DD, and FIG. (A) Top view of cutting insert 1 ″ according to the third embodiment of the present invention, (b) One side view (: short side view), (c) Other side view (: long side view) Figure). It is (a) AA sectional drawing of FIG. 8, (b) BB sectional drawing, (c) CC sectional drawing, (d) DD sectional drawing, (e) EE sectional drawing. (A) top view, (b) one side view (: short side view), (c) other side view (: long side) of a cutting insert 1 ″ ′ according to a fourth embodiment of the present invention Side view). It is (a) AA sectional drawing of FIG. 10, (b) BB sectional drawing, (c) CC sectional drawing, (d) DD sectional drawing, (e) EE sectional drawing. It is a figure explaining each process of the cutting method of the cut material which concerns on this invention.

Explanation of symbols

1 Cutting insert (1A 1st insert)
(1B 2nd insert)
2 Upper surface 3 Lower surface 4 Side surface 5 First blade p1 One end (outer end)
p2 other end (inner side)
p3 bending point 6 through-hole 7 first rake face 71 first region 72 second region 8 second cutting edge 9 first land 10 drill 11 drill holder 12 insert pocket (12A first insert pocket)
(12B 2nd insert pocket)
13 Flute (13A 1st Flute)
(13B 2nd flute)
14 Screw member 15 Breaker groove L Drill holder 11 axis θ Rake angle φ Land angle W Land width

Claims (6)

A drill holder having a first insert pocket formed on the outer peripheral side of the tip portion, and a second insert pocket formed on the center axis side of the tip portion;
A first cutting insert attached to the first insert pocket for performing cutting on the outer peripheral side of the hole bottom;
A drill equipped with a second cutting insert attached to the second insert pocket for cutting on the inner peripheral side of the hole bottom,
Wherein the first cutting insert has a top surface having a first side adjacent to the corner portion and the corner portion, and a first cutting edge which is formed to extend from the front Symbol corner along the first side, of the upper surface A first rake face along the first cutting edge,
Said first cutting edge is provided by bending so that the center in top view projecting outwardly, one end close to the corner portion has a, then the other end was spaced apart from the corner portion, at least A part of the first cutting blade protrudes from the outer peripheral surface of the drill holder and the front end surface along the front end surface of the drill holder, and the corner portion is positioned at the outer peripheral end portion of the drill holder. One end of the first cutting blade is arranged on the outermost surface side of the drill holder,
The first rake face is positioned closer to one end of the first cutting edge than the bending point of the first cutting edge and the rake angle is substantially constant, and from the bending point of the first cutting edge. And a second region that is located on the other end side of the first cutting edge and that increases as the rake angle approaches the other end,
The drill said at the other end of the first cutting edge a first rake face rake angle, being larger than the rake angle of the first rake face in one end of said first cutting edge. The first cutting insert further includes a first land extending from the first cutting edge toward the inside of the upper surface along the first cutting edge;
Claims inclination angle with respect to the lower surface of the first land at the other end of the pre-Symbol first cutting edge, and greater than the inclination angle with respect to the lower surface of the first land at one end of said first cutting edge The drill according to 1 . The drill according to claim 2, wherein an inclination angle of the first land with respect to the lower surface gradually increases from one end of the first cutting blade toward the other end. The first cutting insert further includes a first land extending from the first cutting edge toward the inside of the upper surface along the first cutting edge;
Drill according to claim 1 the width of the first lands, characterized in that less than the width of the first land at one end of said first cutting edge at the other end of the pre-Symbol first cutting edge. The drill according to claim 4, wherein the width of the first land gradually decreases from one end of the first cutting edge toward the other end. A method of cutting a work material,
A step of rotating at least one of the work material and the drill according to any one of claims 1 to 5 ;
Bringing the first cutting edge close to the work material;
Cutting the work material by bringing the first cutting edge into contact with the surface of the work material;
And a step of separating the first cutting edge from the work material.

Images