JP2013208692A - Drill and method for manufacturing cutting workpiece using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drill capable of improving the accuracy of a hole position and the smoothness of an inner wall face of a machined hole.SOLUTION: A drill includes a columnar cutting part including: a first cutting part 11A having a first cutting blade 11a positioned at a top and continuous to a first chisel edge 11a1; a second cutting part 11b having a second cutting blade 11b continuous to a second chisel edge 11b1; first and second grooves 12a, 12b continuous to the first and second cutting blades and spirally extended toward a rear end; and first and second outer peripheral parts extended to the second and first grooves in a tip view. The second cutting part is positioned to be closer to a rear end side than the first cutting part, and the other end of the second cutting blade is positioned between a first intersection 16A which is an intersection of a cutting part outer edge and a first extended line formed by extending the first chisel edge in a rotational axis direction of the cutting part, and a second intersection 16B which is an intersection of the cutting blade outer edge and a second extended line formed by extending a center line in parallel with the first cutting blade and passing through a rotational axis in the rotational axis direction.

Description

  The present invention relates to a drill and a method of manufacturing a cut product using the drill.

  Conventionally, for example, Patent Document 1 discloses a single blade provided with a cutting blade that continues to a pair of chisel edges and extends to the outer peripheral end of the drill body, and a non-cutting portion whose rotational trajectory is retracted compared to the cutting blade. A drill is disclosed. And the structure by which two main grooves and two lands connected to it were provided from the front-end | tip of a drill main body corresponding to a cutting blade and a non-cutting part is disclosed.

  However, in such drilling with one cutting edge, it cannot be said that the cutting balance is still sufficient, and it has been difficult to improve the hole position accuracy and inner wall smoothness of the processed holes.

  Therefore, a drill capable of improving the hole position accuracy and inner wall surface smoothness of the processed hole and a method of manufacturing a cut product using the drill have been demanded.

JP 2010-162643 A

The drill which concerns on one Embodiment of this invention has the 1st cutting part which has the 1st chisel edge located in the front-end | tip part, and the 1st cutting edge in which one end continues to the said 1st chisel edge, A second cutting portion having a second chisel edge continuously located on the first chisel edge and a second cutting edge having one end continuous with the second chisel edge; and continuously with the first cutting edge A first groove that extends spirally toward the rear end, a second groove that continues to the second cutting edge and extends spirally toward the rear end, and A first outer peripheral portion that is continuous with the other end of the one cutting edge and extends to the second groove along the outer edge in a front end view;
A cylindrical cutting portion that is continuous with the other end of the second cutting edge and has a second outer peripheral portion extending to the first groove along the outer edge in the front end view, and in the front end view, When the part having the same distance from the rotation axis of the cutting part is viewed, the second cutting part is located closer to the rear end part than the first cutting part. The other end of the cutting edge includes a first intersection that is an intersection of a first extension line formed by extending the first chisel edge in the rotation axis direction of the cutting portion and the outer edge of the cutting portion, and the first cutting edge. It is located between a second extension line formed by extending a center line parallel to the blade and passing through the rotation axis in the direction of the rotation axis and a second intersection point that is an intersection of the outer edge of the cutting portion.

  A manufacturing method of a cut product according to an embodiment of the present invention includes a step of rotating the drill around a rotation axis, and the first cutting edge and the second cutting edge of the rotating drill. A step of contacting the work material, and a step of separating the work material from the drill.

According to the drill of one embodiment of the present invention, when the portion having the same distance from the rotation axis of the cutting part is viewed in the front end view, the second cutting part is more than the first cutting part. Since it is located on the rear end side, in the initial stage of drilling, only the first cutting part bites into the work material first and performs cutting, so the center position of the rotation of the drill Is slightly displaced with respect to the rotation axis of the cutting part, thereby forming a machining hole having a slightly smaller diameter with respect to the outer edge (outer diameter) of the cutting part. In the front end view, the other end of the second cutting edge is an intersection of a first extension line formed by extending the first chisel edge in the rotation axis direction of the cutting part and the outer edge of the cutting part. A second intersection point that is an intersection point between a first intersection point, a second extension line that is parallel to the first cutting edge and passes through the rotation axis, and extends in the rotation axis direction, and the outer edge of the cutting portion. When the second cutting part (second cutting edge) is in a stage that contributes to the cutting, the outer edge of the cutting part as described above is slightly increased. A small-diameter machining hole can be cut by the other end of the second cutting blade located substantially opposite to the first cutting part and the rotation shaft so as to expand to the size of the outer edge of the cutting part. At the same time, it is possible to improve the smoothness by removing the burrs existing in the processed holes and the irregularities on the inner walls of the processed holes. Kill.

It is a figure which shows the drill which concerns on embodiment of this invention, (a) is a whole side view, (b) is the front view seen from the front-end | tip part side, (c) is A of FIG. FIG. It is the elements on larger scale which show the front-end | tip part side among the cutting parts of the drill shown in FIG. 1, (a) is the side view seen from arrow A, (b) is the side view seen from arrow B. It is the elements on larger scale which show the front-end | tip part side among the cutting parts of the drill shown in FIG. 1, (a) is the side view seen from arrow C, (b) is the side view seen from arrow D. FIG. 2 is a view showing a side view of the drill shown in FIG. 1 corresponding to a tip view with reference to the rotation axis O, (a) is a side view seen from an arrow E, and (b) is seen from an arrow F. FIG. FIG. 2 is a view showing a side view of the drill shown in FIG. 1 corresponding to a tip view with reference to the rotation axis O, (a) is a side view seen from an arrow G, and (b) is seen from an arrow H. FIG. It is a figure explaining the manufacturing method of the cut workpiece which concerns on embodiment of this invention, (a) is a figure which shows the process of making a drill approach a Y direction toward a workpiece, (b) is a figure which covers a drill. It is a figure which shows the process made to contact a cutting material, (c) is a figure which shows the process of separating a drill from a work material in a Z direction.

<Drill>
(First embodiment)
Hereinafter, a drill according to an embodiment of the present invention will be described in detail with reference to FIGS.

  As shown in FIG. 1A, a drill 1 of the present embodiment is roughly composed of a main body 20 that is gripped by a rotating spindle or the like of a machine tool, and a cutting portion 10 provided on one end side of the main body 20. And. The main body 20 is a part designed according to the shape of the rotating shaft of the machine tool. The cutting unit 10 is a part that contacts the work material 30. The arrow a indicates the direction of rotation of the drill 1.

As shown in FIGS. 2 and 3, the cutting unit 10 is a part having a main role in cutting the work material 30. Specifically, two cutting edges 11 (a first cutting edge 11a and a second cutting edge 11b) that are positioned apart from each other via a pair of chisel edges 11a1 and 11b1 to be described later are formed at the distal end portion 10a. In addition, two grooves 12 (first groove 12a and second groove 12b) corresponding to the two cutting edges 11 are formed on the outer edge (outer periphery) 10c of the cutting portion 10 from the front end portion 10a to the rear end portion 10b. Has been. Here, as shown in FIGS. 1B and 4, the first cutting part 11A has a first chisel edge 11a1 and a first cutting edge 11a, and the second cutting part 11B has a second chisel edge 11b1 and a second chisel edge 11b1. It has a cutting edge 11b. In this embodiment,
The first cutting part 11A functions as a main cutting edge, and the second cutting part 11B functions as an auxiliary cutting edge.

  Moreover, in this embodiment, the shape of the cutting part 10 is a column shape. That is, in the cross section perpendicular to the rotation axis O, the cutting portion 10 has a relationship T1 and T2 where T1 is a diameter at the tip portion 10a and T2 is a diameter at a portion other than the tip portion 10a. doing. Further, the diameter of the cutting portion 10 is constant from the front end portion 10a to the rear end portion 10b in a cross section perpendicular to the rotation axis O. In addition, the outer edge (outer periphery) 10c of the cutting part 10 is shown as the continuous line in FIG.1 (b), FIG.4, and FIG.5. Here, in this specification, the rotation axis O is a line passing through the center of the cutting part 10 in the front end view and passing through a point where the pair of chisel edges 11a1 and 11b1 are continuous. Further, in the present specification, the front end view means that the drill 1 is viewed from the front end portion 10a side.

  The two chisel edges (the first chisel edge 11a1 and the second chisel edge 11b1) are located on the most distal end portion 10a side of the cutting portion 10, as shown in FIGS. In the present embodiment, the first chisel edge 11a1 has a role of cutting the work material 30 together with the first cutting edge 11a and the second cutting edge 11b, whereas the second chisel edge 11b1 is positively active. It does not have a role of cutting. As shown in FIG. 1B, the first chisel edge 11a1 and the second chisel edge 11b1 do not exist at a rotationally symmetric position of 180 ° with respect to the rotation axis O (axis) of the cutting portion 10. . Specifically, as shown in FIG. 1B, the second zel edge 11b1 is inclined with respect to the first chisel edge 11a1 when viewed from the front end. In addition, as shown in FIG. 1B, the length of the second zel edge 11b1 is longer than the length of the first chisel edge 11a1. According to this, the distance between the end of the second zel edge 11b1 on the outer edge 10c side and the outer edge 10c can be reduced, and a large core thickness of the drill 1 can be ensured, which contributes to an improvement in drill strength. To do.

  As shown in FIG. 4, when viewed from the side, the inclination angle θ11a1 of the first chisel edge 11a1 is greater than the inclination angle θ11b1 of the second chisel edge 11b1 when the plane perpendicular to the rotation axis O of the cutting portion 10 is used as a reference. Is also small. 4A and 4B are views showing the side view and the tip view of the drill 1 in correspondence with each other. FIG. 4A is a side view seen from an arrow E perpendicular to the first chisel edge 11a1, and FIG. It is the side view seen from the arrow F perpendicular | vertical to 11b1. For example, the tilt angle θ11a1 of the first chisel edge 11a1 can be set to 5 to 10 ° and the tilt angle θ11b1 of the second chisel edge 11b1 can be set to 10 to 25 ° with respect to the plane perpendicular to the rotation axis O. According to this, at the time of drilling the work material 30, the first chisel edge 11a1 comes into contact with the work material 30 prior to the second chisel edge 11b1, and is used for cutting work. Here, what is necessary is just to use the 2nd zel edge 11b1 as a cutting blade for assisting the cutting process by the 1st chisel edge 11a1 as needed.

  In the present embodiment, as shown in FIG. 1B, a third chisel edge 11c1 is further provided at the intersection of a later-described third flank 14c and fourth flank 14d. According to this, a positional balance can be improved by providing in addition to the 1st chisel edge 11a1 and the 2nd chisel edge 11b1 which are mutually asymmetrically arranged, and straight advanceability of the drill 1 can be improved. In the present embodiment, at the time of drilling, the third chisel edge 11c1 is provided at a position where the bottom surface of the drilled hole is slightly rubbed, so that the straightness of the drill 1 can be further improved.

The two cutting edges 11 are formed in the front-end | tip part 10a of the cutting part 10, as shown in FIG. In the present embodiment, the first cutting edge 11a and the second cutting edge 11b also do not exist at rotationally symmetric positions of 180 ° with respect to the rotation axis O (axis line) of the cutting unit 10. Specifically, as shown in FIG. 1B, the second cutting edge 11 with respect to the first cutting edge 11a in the front end view.
b is inclined. Moreover, as shown in FIG.1 (b), the length of the 2nd cutting blade 11b is longer than the length of the 1st cutting blade 11a. In addition, as shown in FIG.1 (b), the 2nd cutting blade 11b is curvilinear in front end view. Specifically, in the front end view, the second cutting edge 11b has a curved shape that is convex toward the outer edge 10c. In addition, it is preferable that the angle | corner which the 1st chisel edge 11a1 and the 1st cutting edge 11a make is set to 130-150 degrees, for example in front end view.

  As shown in FIG. 5, when viewed from the side, the inclination angle θ11a of the first cutting edge 11a is the inclination angle of the second cutting edge 11b when the plane perpendicular to the rotation axis O of the cutting unit 10 is used as a reference. It is smaller than θ11b. FIG. 5 is a view showing the side view and the tip view of the drill 1 in correspondence with each other, (a) is a side view seen from an arrow E perpendicular to the first cutting edge 11a, and (b) is a second view. It is the side view seen from the arrow F perpendicular | vertical to the cutting blade 11b. For example, with respect to a plane perpendicular to the rotation axis O, the inclination angle θ11a of the first cutting edge 11a is set to 15 to 40 °, and the inclination angle θ11b of the second cutting edge 11b is set to 30 to 60 °. it can. According to this, in combination with the magnitude relationship between the inclination angle θ11a1 of the first chisel edge 11a1 and the inclination angle θ11b1 of the second chisel edge 11b1 as described above, the first cutting edge 11a is ahead of the second cutting edge 11b. Is brought into contact with the work material 30 for cutting. Here, the 2nd cutting blade 11b is used as a cutting blade for assisting the cutting process by the 1st cutting blade 11a. Specifically, it has a role of cutting a hole having a slightly smaller diameter with respect to the outer edge 10 c formed by the first cutting part 11 </ b> A so as to expand to the size of the outer edge 10 c of the cutting part 10. In other words, the second cutting edge 11b has a region corresponding to the difference between the machining hole having a slightly smaller diameter with respect to the outer edge 10c and the outer edge (outer diameter) 10c of the cutting portion 10 as the other end 11bb of the second cutting edge 11b. It can cut using the side part.

  Further, on the first cutting part 11A side, the first flank 14a continuous with the first cutting edge 11a is inclined to the rear end part 10b side, for example, by 5 to 15 ° with respect to the first cutting edge 11a. And the 2nd flank 14b continuing to the 1st flank 14a should just set so that it may incline to the rear end part 10b side 5-40 degrees on the basis of the 1st flank 14a. On the other hand, on the second cutting portion 11B side, the third flank 14c continuous with the second chisel edge 11b1 is inclined to the rear end portion 10b side, for example, by 10 to 40 ° with respect to the second chisel edge 11b1, and The fourth flank 14d that is continuous with the third chisel edge 11c1 may be set so as to be inclined toward the rear end portion 10b, for example, by 10 to 40 ° with respect to the third chisel edge 11c1.

  As described above, according to the drill 1 according to the present embodiment, when the portion having the same distance from the rotation axis O of the cutting unit 10 is viewed in the front end view, as shown in FIGS. Since the 2nd cutting part 11B is located in the rear end part 10b side rather than the 1 cutting part 11A, only the 1st cutting part 11A precedes the work material 30 in the initial stage of drilling. Since cutting is performed by biting, the center position of the rotation of the drill 1 is slightly deviated from the rotation axis O of the cutting part 10, so that the diameter is slightly smaller than the outer edge (outer diameter) 10 c of the cutting part 10. A processing hole 31 is formed. That is, as shown in FIG. 4 (a), it is possible to compare the positions in the side view of the first cutting part 11A and the second cutting part 11B passing through the same circle with the rotation axis O as the midpoint in the front end view, It is clearly shown that the second cutting portion 11B is located closer to the rear end portion 10b than the first cutting portion 11A at a portion where the distance from the rotation axis O is the same. For example, when viewing the plane P perpendicular to the rotation axis O and the planes L1 to L3 parallel to the plane P, the second cutting is performed more than the first cutting portion 11A in any of the planes L1, L2, and L3. It can be seen that the part 11B is located on the rear end part 10b side. Therefore, only the first cutting part 11 </ b> A bites into the work material 30 first and performs cutting.

Then, as shown in FIG. 1B, the other end 11bb of the second cutting edge 11b, when viewed from the tip, is a first extension line formed by extending the first chisel edge 11a1 in the direction of the rotation axis O of the cutting portion 10. A first intersection 16A, which is an intersection with the outer edge 10c of the cutting part 10, and a second extension line formed by extending a center line parallel to the first cutting edge 11a and passing through the rotation axis O in the direction of the rotation axis O, and the cutting part 10 outer edges 10c
Since the second cutting portion 11B (second cutting edge 11b) is in a stage that contributes to the cutting, the above-described process is performed. The other end 11bb of the second cutting edge 11b in which the machining hole 31 having a slightly smaller diameter with respect to the outer edge 10c of the cutting part 10 is positioned on the substantially opposite side across the first cutting part 11A and the rotation axis O. Thus, cutting can be performed so as to expand to the size of the outer edge 10c of the cutting portion 10, and burrs existing in the processed hole 31 and unevenness of the inner wall of the processed hole 31 can be removed to improve smoothness.

  In the present embodiment, the other end 11ab of the first cutting edge 11a is point-symmetric with the other end 11bb of the second cutting edge 11b with respect to the rotation axis O of the cutting portion 10 in the front end view. According to this, the position balance of the 1st cutting blade 11a which functions as a main cutting blade and the 2nd cutting blade 11b which functions as an auxiliary cutting blade is good, and exhibits the above effects more effectively. Can do.

  The two grooves 12 are mainly intended to discharge chips generated by the two cutting edges 11. Specifically, as shown in FIGS. 1 to 3, the first groove 12 a and the second groove 12 b are continuous with the first cutting edge 11 a and the second cutting edge 11 b, respectively, and the tip of the cutting portion 10. It is located in a spiral shape from the part 10a to the rear end part 10b (main body part 20 side). At the time of cutting, chips formed by the first cutting edge 11a are discharged to the rear end portion 10b side through the first groove 12a that is basically continuous to the first cutting edge 11a, and the second Chips formed by the cutting blade 11b are discharged to the rear end portion 10b side through the second groove 12b that is basically continuous with the second cutting blade 11b. In this embodiment, as shown in FIG. 1B, the depth D2 of the second groove 12b is the depth of the first groove 12a with respect to the rotation axis O side with respect to the outer edge 10c of the cutting portion 10. It is smaller than the depth D1. As described above, since the second cutting edge 11b is a cutting edge having a function of assisting the cutting with the first cutting edge 11a, the second cutting edge 11b also has a depth D2 of the second groove 12b continuous to the second cutting edge 11b. This is because it is only necessary to ensure a depth within a range necessary for discharging chips generated by the blade 11b. And by setting the depth D2 of the 2nd groove | channel 12b smaller than the depth D1 of the 1st groove | channel 12a, since the core thickness of the drill 1 can be ensured large, it contributes to the improvement of drill strength. Further, the twist angle of the first groove 12a and the twist angle of the second groove 12b are the same. Further, the chips generated by the first chisel edge 11a1 continuous with the one end 11aa of the first cutting edge 11a and the chips generated by the second chisel edge 11b1 continuous with the one end 11ba of the second cutting edge 11b are: It is discharged to the rear end portion 10b side through the first groove 12a and the second groove 12b via the fourth flank 14d and the second flank 14b positioned corresponding to the chisel edges 11a1 and 11b1, respectively.

  As shown in FIG. 1B, the outer peripheral portion 16 (first outer peripheral portion 16a, second outer peripheral portion 16b) is a region where the groove 12 is not formed, and in this region, the drill diameter (outer diameter) is The size before the groove 12 is formed is maintained. That is, the outer peripheral portion 16 is a portion substantially corresponding to the outer edge (outer periphery) 10c of the cutting portion 10 in a cross-sectional view, and has an arc shape.

  As shown in FIG. 1B, the first outer peripheral portion 16a is continuous with the other end 11ab of the first cutting edge 11a, and extends to the second groove 12b along the outer edge 10c in the front end view. As shown in FIG. 1B, the first outer peripheral portion 16a is located on the same circumference as the outer edge 10c in the front end view. According to this, the 1st outer peripheral part 16a is provided with the function which guides the drill 1 in sliding contact with the inner wall of the processed hole 31 of the workpiece 30 at the time of drilling.

  As shown in FIG. 1B, the second outer peripheral portion 16b is continuous with the other end 11bb of the second cutting edge 11b, and extends to the first groove 12a along the outer edge 10c in the front end view. Similar to the first outer peripheral portion 16a, the second outer peripheral portion 16b is located on the same circumference as the outer edge 10c in the front end view, as shown in FIG. 1 (b). According to this, the 2nd outer peripheral part 16b is provided with the function which slides and contacts the inner wall of the process hole 31 of the workpiece 30, and guides the drill 1 at the time of drilling.

  In the present embodiment, as shown in FIG. 1B, the length of the second outer peripheral portion 16b along the outer edge 10c of the cutting portion 10 is shorter than the first outer peripheral portion 16a in the front end view. According to this, the strength of the first outer peripheral portion 16a continuing to the first cutting portion 11A functioning as the main cutting edge is strong, and the second outer peripheral portion 16b continuing to the second cutting portion 11B functioning as an auxiliary cutting edge. By securing only the required strength, it is possible to reduce scorching due to contact with the inner wall of the processed hole 31.

  In addition, the drill 1 of this embodiment is used suitably, for example as a small diameter drill and a deep hole processing drill whose outer diameter of the cutting blade 11 is less than 0.6 mm, preferably less than 0.3 mm. In particular, it is suitable for drilling a printed circuit board or the like. Further, the drill 1 of the present embodiment is made of ultra-fine particle carbide, for example, the length of the axis (the length from the cutting edge 11 to the end of the groove 12) is L, and the diameter (outside of the cutting edge 11). When the diameter is D, it is suitably used for deep hole machining where L / D is 5 or more.

<Manufacturing method of cut product>
Next, the manufacturing method of the cut workpiece which concerns on embodiment of this invention is demonstrated in detail, giving the case where the drill 1 which concerns on the above-mentioned embodiment is used as an example. Hereinafter, a description will be given with reference to FIG.

  The manufacturing method of the cut workpiece according to the present embodiment includes the following steps (i) to (iv).

(I) The process of arrange | positioning the drill 1 upwards with respect to the prepared work material 30 (refer Fig.6 (a)).

  (Ii) A step of rotating the drill 1 in the direction of the arrow a around the rotation axis O to bring the drill 1 closer to the work material 30 (see FIGS. 6A and 6B).

  This step can be performed, for example, by fixing the work material 30 on a table of a machine tool to which the drill 1 is attached and bringing the drill 1 closer in a rotated state. In this step, the work material 30 and the drill 1 may be relatively close to each other. For example, the work material 30 may be close to the drill 1.

(Iii) The drill 1 rotating by bringing the drill 1 closer to the work material 30
The first cutting blade 11a and the second cutting blade 11b are brought into contact with desired positions on the surface of the work material 30 to form a machining hole (through hole) 31 in the work material 30 (FIG. 6B). )reference).

  In this step, from the viewpoint of obtaining a good finished surface, it is preferable to set so that a part of the cutting portion 10 of the drill 1 on the rear end portion 10 b side does not penetrate the work material 30. That is, by making this partial region function as a margin region for chip discharge, it is possible to achieve excellent chip discharge properties through the region.

  (Iv) A step of separating the drill 1 from the work material 30 (see FIG. 6C).

  Also in this step, similarly to the above-described step (ii), the work material 30 and the drill 1 may be relatively separated from each other. For example, the work material 30 may be separated from the drill 1.

  By going through the steps as described above, excellent hole workability can be exhibited.

In addition, when performing the cutting process of the workpiece 30 as described above a plurality of times, for example, when forming a plurality of processed holes (through holes) 31 on one workpiece 30, the drill 1 What is necessary is just to repeat the process which makes the 1st cutting edge 11a and the 2nd cutting edge 11b of the drill 1 contact the different location of the cut material 30, hold | maintaining the state which rotated.

  As mentioned above, although some embodiment and modification which concern on this invention were illustrated, this invention is not limited to these, It cannot be overemphasized that it is arbitrary, unless it deviates from the summary of this invention. .

  For example, the shape of the cutting part 10 is not limited to the structure of the above-mentioned embodiment, The shape normally used by those skilled in the art can be adopted. For example, the cutting part 10 may be tapered so that the core thickness of the inscribed circle increases from the front end part 10a toward the rear end part 10b. Moreover, the cutting part 10 may be inclined so that the drill diameter (outer diameter) becomes larger or smaller as it goes from the front end part 10a to the rear end part 10b. Further, the cutting part 10 may be provided with a so-called undercut part or clearance part.

  In the above-described embodiment, the groove widths of the first groove 12a and the second groove 12b are the same, but instead, the one of the first groove 12a and the second groove 12b that is located on the tip portion 10a side. The groove width may be increased. According to this, it becomes possible to discharge | emit effectively about the comparatively big chip through the groove | channel 12 by the side of the front-end | tip part 10a. Further, the distance may increase or decrease from the front end portion 10a toward the rear end portion 10b.

  Moreover, the groove length of the 1st groove | channel 12a and the 2nd groove | channel 12b may differ. Furthermore, the two grooves may be joined by changing the twist angle of one or both of the first groove 12a and the second groove 12b.

DESCRIPTION OF SYMBOLS 1 Drill 10 Cutting part 10a Tip part 10b Rear end part 10c Outer edge 11 Cutting edge 11a First cutting edge 11aa One end 11ab Other end 11b Second cutting edge 11ba One end 11bb Other end 11a1 First chisel edge 11b1 Second chisel edge 11c1 Third chisel edge 11A First cutting part 11B Second cutting part 12 Groove 12a First groove 12b Second groove 14 Flank 14a First flank 14b Second flank 14c Third flank 14d Fourth flank 16 Outer part 16a First outer part 16b 2nd outer peripheral part 16A 1st intersection 16B 2nd intersection 20 Main-body part 30 Work material 31 Process hole (through-hole)
O Rotating shaft

Claims (13)

A first cutting portion having a first chisel edge located at a tip portion and a first cutting edge having one end continuous to the first chisel edge;
A second cutting portion having a second chisel edge continuously located at the tip portion of the first chisel edge and a second cutting edge having one end continuous with the second chisel edge;
A first groove that is continuous with the first cutting edge and extends spirally toward the rear end;
A second groove that is continuous with the second cutting edge and extends spirally toward the rear end;
A first outer peripheral portion that is continuous with the other end of the first cutting edge and extends to the second groove along the outer edge in a front end view;
A cylindrical cutting part that is continuous with the other end of the second cutting edge and has a second outer peripheral part extending to the first groove along the outer edge in a front end view;
When looking at the same distance from the rotation axis of the cutting part in the front end view, the second cutting part is located closer to the rear end part than the first cutting part,
In the front end view, the other end of the second cutting edge is an intersection of a first extension line formed by extending the first chisel edge in the rotation axis direction of the cutting portion and the outer edge of the cutting portion. An intersection point and a second intersection point that is an intersection point of a second extension line formed by extending a center line parallel to the first cutting edge and passing through the rotation axis in the direction of the rotation axis, and the outer edge of the cutting portion. A drill located between them.   2. The drill according to claim 1, wherein the other end of the first cutting edge is point-symmetric with the other end of the second cutting edge with respect to the rotation axis of the cutting portion in a front end view.   In a side view, the inclination angle of the first cutting edge is smaller than the inclination angle of the second cutting edge when a plane perpendicular to the rotation axis of the cutting part is used as a reference. The drill described.   The drill according to any one of claims 1 to 3, wherein the second cutting edge is inclined with respect to the first cutting edge in a front end view.   The drill according to any one of claims 1 to 4, wherein the second cutting edge has a curved shape in a front end view.   6. The drill according to claim 5, wherein the second cutting edge has a curved shape convex toward the outer edge in a front end view.   The length of the said 2nd cutting blade is a drill in any one of Claims 1-6 longer than the length of the said 1st cutting blade.   8. The tilt angle of the first chisel edge is smaller than the tilt angle of the second chisel edge when a side surface of the cutting portion is perpendicular to the rotation axis in a side view. Drill as described in.   The drill according to any one of claims 1 to 8, wherein a length of the second chisel edge is longer than a length of the first chisel edge.   The drill according to any one of claims 1 to 9, wherein the second chisel edge is inclined with respect to the first chisel edge in a front end view.   The drill according to any one of claims 1 to 10, wherein the second outer peripheral portion has a shorter length along the outer edge of the cutting portion than the first outer peripheral portion in a front end view.   The depth to the said rotating shaft side on the basis of the said outer edge of the said cutting part has the depth D2 of the said 2nd groove | channel smaller than the depth D1 of the said 1st groove | channel in any one of Claims 1-11. The drill described. Rotating the drill according to any one of claims 1 to 12 around a rotation axis;
Contacting the work piece with the first cutting edge and the second cutting edge of the rotating drill;
Separating the work material and the drill;
A method for manufacturing a cut product.

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