JP6410544B2 - Drill and cutting method - Google Patents

Description

  The present invention relates to a drill and a method for manufacturing a cut product.

  In Patent Document 1, in a stepped drill, the first-stage cutting edge from the tip is less than the second and subsequent cutting edges, the number of cutting blades is reduced, the tip angle is increased, or It is described that the thrust resistance of cutting is reduced by increasing the clearance angle. Further, Patent Document 1 describes that a work material in which a metal member and a fiber reinforced resin composite material are stacked is drilled at a time using the above-described drill.

  However, when the above-described work material is drilled using the drill of Patent Document 1, there is a problem that the operability of the drill is lowered because the thrust resistance during cutting becomes unstable. This tendency was remarkable in the hand drill. Moreover, since the drill of patent document 1 has a complicated structure, there also existed a problem that it was difficult to manufacture.

JP 2013-843 A

  One of the problems of the present invention is to provide a drill and a method for manufacturing a cut workpiece, which are relatively simple in structure and have stable operability and excellent hole workability.

  The drill according to the embodiment of the present invention has a first region located at the tip portion and at least one step portion having a diameter that increases toward the rear end portion side. And a second region that is continuous with the first region at an end portion that is positioned, and includes a substantially cylindrical cutting portion that extends along the rotation axis, and the at least one step portion is The first region has a plurality of first cutting blades positioned at the front end, and the plurality of first cutting blades side to the rear end side. A plurality of first grooves extending toward the end, and from the end located on the outer peripheral side of the cutting portion of each of the plurality of first cutting blades toward the rear end portion. The diameter is reduced, and the second region includes a plurality of second rear cutting edges located in the rear stage portion, 2 A plurality of second rear grooves extending from the rear cutting edge side toward the rear end portion side, and an end portion of each of the plurality of second rear cutting blades located on the outer peripheral portion side from the rear side. And a rear region having a constant diameter toward the end side.

  The manufacturing method of the cut workpiece which concerns on embodiment of this invention is a process which rotates the drill which concerns on embodiment mentioned above around the said rotating shaft, These 1st cutting blades of the said drill which is rotating, and these plurality A step of bringing the second rear cutting edge into contact with the work material, and a step of separating the drill from the work material.

  The drill according to the embodiment of the present invention has an effect that the configuration is relatively simple and the hole workability is excellent.

It is a figure which shows the drill which concerns on embodiment of this invention, (a) is a perspective view, (b) is an enlarged front view. It is the figure which looked at the drill of FIG. 1 from the direction perpendicular | vertical to a rotating shaft, (a) is a X1 arrow view of FIG.1 (b), (b) is a X2 arrow view of FIG.1 (b), (c ) Is a view taken along arrow X3 in FIG. 1B, and FIG. 5D is a view taken along arrow X4 in FIG. In addition, each arrow of X1-X4 of FIG.1 (b) has shown the direction for every 90 degrees in the opposite direction to the rotation direction of a drill. It is the elements on larger scale which looked at the front-end | tip part vicinity of the drill of FIG. 1 from the direction perpendicular | vertical to a rotating shaft. It is a figure which shows the drill of FIG. 1, Comprising: It is a broken sectional view which shows the state which cut | disconnected the cutting part along each line of Y1-Y3 of FIG.2 (b), (a) is a Y1-Y1 line expanded fracture surface. FIG. 5B is an enlarged sectional view taken along line Y2-Y2, and FIG. 5C is an enlarged sectional view taken along line Y3-Y3. It is a figure which shows the manufacturing method of the cut workpiece which concerns on embodiment of this invention, (a)-(c) is explanatory drawing which shows each process.

<Drill>
Hereinafter, the drill which concerns on embodiment of this invention is demonstrated in detail using FIGS. 1-4.
As shown in FIG. 1, the drill 1 of the present embodiment includes a substantially cylindrical cutting portion 2 that can rotate in the direction of arrow A around the rotation axis S and extends along the rotation axis S. . The cutting part 2 of the present embodiment is a part having a main role in the cutting of the work material 100 to be described later, and has a first region 3 and a second region 4 in order from the tip 1a side of the drill 1. .

(First area)
The first region 3 is located at the tip 1 a of the drill 1. As shown in FIGS. 1 and 2, the first region 3 of the present embodiment includes a plurality of first cutting edges 31 positioned at the tip of the drill 1 and a plurality of first cutting edges 31 from the side of the plurality of first cutting edges 31. And a plurality of first grooves 32 extending toward the rear end 1b side.

  In the present embodiment, the plurality of first cutting edges 31 are positioned so as to be rotationally symmetric with respect to the rotation axis S at intervals from each other in the front end view shown in FIG. The tip view means a state in which the drill 1 is viewed from the tip 1a side of the drill 1. The plurality of first cutting edges 31 of the present embodiment are three in number, and are positioned so as to be 120 ° rotationally symmetric with respect to the rotation axis S in the front end view. According to such a configuration, it becomes possible to improve the straight running stability of the drill 1 when machining the work material 100. In addition, the number of the 1st cutting blade 31 is not limited to three, Usually, it can select arbitrarily from 2-5 ranges.

  All the chips generated from the plurality of first cutting edges 31 pass through the plurality of first grooves 32 and are discharged to the rear end 1b side. Since the plurality of first grooves 32 are all positioned corresponding to the plurality of first cutting edges 31, the number of first grooves 32 is the same as the number of first cutting edges 31. In the present embodiment, since the number of first cutting edges 31 is three, the number of first grooves 32 is also three.

  The plurality of first grooves 32 of the present embodiment are all continuous with the plurality of first cutting edges 31. According to such a configuration, it is possible to improve the biting property to the work material 100. In addition, a rake face can also be located between the 1st groove | channel 32 and the 1st cutting blade 31 from a viewpoint of stabilizing the discharge direction of the chip | tip produced | generated from the 1st cutting blade 31. FIG.

  The plurality of first grooves 32 of the present embodiment are separated from each other over the entire length of the first region 3. Further, each of the plurality of first grooves 32 of the present embodiment extends in a spiral shape. The plurality of first grooves 32 can also extend substantially parallel to the rotation axis S, that is, straight.

  The 1st field 3 of this embodiment is located in the back of the direction of rotation of drill 1 shown with arrow A rather than the 1st cutting edge 31 among the tip of drill 1 as shown in Drawing 1 (b). A first flank 34 is further provided. The first flank 34 is a part having a role of reducing the cutting resistance by avoiding contact with the work material 100 and has a clearance angle. The clearance angle of the first clearance surface 34 means an angle formed by a reference surface (not shown) perpendicular to the rotation axis S and the first clearance surface 34. The clearance angle of the first flank 34 is preferably 5 to 30 °, but is not limited thereto.

  The first region 3 of the present embodiment further has a biting portion 35 located on the rotation axis S side of the tip of the drill 1. The biting portion 35 is a portion that improves the biting property to the work material 100, and is configured by applying a so-called thinning process for thinning the thickness to the chisel edge. A chisel edge shall mean the site | part comprised when the edge part located in the rotating shaft S side of the some 1st cutting blade 31 mutually cross | intersects.

  In the present embodiment, the biting portion 35 is configured by thinning the chisel edge so that the chisel edge does not remain. The plurality of first cutting edges 31 are either continuous to the biting portion 35 or connected by one or more straight lines or curves. According to these configurations, it is possible to improve the biting property to the work material 100. Note that the thinning process is not limited to performing the chisel edge so as not to remain, and can be performed so that a part of the chisel edge remains depending on the composition of the work material 100, the cutting conditions, and the like.

(Second area)
On the other hand, as shown in FIG. 1A, the second region 4 is continuous to the first region 3 at one end 4a located on the first region 3 side. The second region 4 of the present embodiment has at least one step portion 5. As shown in FIG. 3, the stepped portion 5 is a portion where the diameter D becomes larger toward the rear end portion 1 b side. The diameter D can be determined in a cross-sectional view perpendicular to the rotation axis S as shown in FIG.

  The number of the step portions 5 may be at least one, and can be arbitrarily selected from 1 to 5 ranges according to the composition of the work material 100, cutting conditions, and the like. In the present embodiment, as shown in FIG. 3, the number of step portions 5 is two. The step portion 5 of the present embodiment has a front step portion 6 and a rear step portion 7 in order from the front end portion 1a side.

  The front stage portion 6 is located closer to the distal end portion 1 a than the rear stage portion 7. In addition, when the step part 5 has the front stage part 6 like this embodiment, the number of the front stage parts 6 should just be at least one.

  The rear stage part 7 is located on the rear end part 1b side. More specifically, the rear stage portion 7 is located closest to the rear end portion 1 b in the step section 5. When the number of the step portions 5 is one, this one step portion 5 becomes the rear step portion 7.

  The second region 4 of the present embodiment includes a plurality of second front cutting blades 61 positioned in the front stage portion 6 and a plurality extending from the plurality of second front cutting blades 61 toward the rear end portion 1b. The second front groove 62 is further included. Moreover, the 2nd area | region 4 of this embodiment is extended toward the back end part 1b side from the some 2nd back cutting edge 71 located in the back | latter stage part 7, and the some 2nd back cutting edge 71 side. And a plurality of second rear grooves 72.

  In the present embodiment, the plurality of second front cutting edges 61 and the plurality of second rear cutting edges 71 are all the same as the plurality of first cutting edges 31 described above in the front end view shown in FIG. They are positioned so as to be rotationally symmetric with respect to the rotation axis S at intervals. In the present embodiment, the number of each of the second front cutting edge 61 and the second rear cutting edge 71 is three, and the second front cutting edge 61 and the second rear cutting edge 71 are positioned so as to be 120 ° rotationally symmetric with respect to the rotation axis S in the front end view. doing. In addition, the number of each of the 2nd front cutting edge 61 and the 2nd back cutting edge 71 is not limited to three, Usually, it can select arbitrarily from 2-5 ranges.

  In the present embodiment, the lengths of the plurality of second front cutting edges 61 and the plurality of second rear cutting edges 71 are longer than the lengths of the plurality of first cutting edges 31 in the front end view shown in FIG. Is also small. In other words, in the front end view, the lengths of the plurality of first cutting edges 31 are larger than the lengths of the plurality of second front cutting edges 61 and the plurality of second rear cutting edges 71, respectively. According to such a configuration, the peripheral speed is relatively fast and the second front cutting edge 61 and the second rear cutting edge 71 that are susceptible to a load are prevented from being damaged. In the present embodiment, the lengths of the plurality of second rear cutting edges 71 are larger than the lengths of the plurality of second front cutting edges 61 in the front end view.

  As shown in FIGS. 1A and 2, all chips generated from the plurality of second front cutting edges 61 are discharged to the rear end portion 1 b side through the plurality of second front grooves 62. Similarly, all chips generated from the plurality of second rear cutting edges 71 are discharged to the rear end portion 1 b side through the plurality of second rear grooves 72.

  Since the plurality of second front grooves 62 are positioned corresponding to the plurality of second front cutting edges 61, the number of second front grooves 62 is the same as the number of second front cutting edges 61. Similarly, since the plurality of second rear grooves 72 are positioned corresponding to the plurality of second rear cutting edges 71, the number of second rear grooves 72 is the same as the number of second rear cutting edges 71. It is. In the present embodiment, since the number of each of the second front cutting edge 61 and the second rear cutting edge 71 is three, the number of each of the second front groove 62 and the second rear groove 72 is also three. .

  All of the plurality of second front grooves 62 of the present embodiment are continuous with the plurality of second front cutting edges 61. Similarly, all of the plurality of second rear grooves 72 of the present embodiment are continuous with the plurality of second rear cutting edges 71. According to these configurations, it is possible to improve the biting property to the work material 100. In addition, from the viewpoint of stabilizing the discharge direction of the chips generated from the second front cutting edge 61, a rake face can be positioned between the second front groove 62 and the second front cutting edge 61. This also applies to the second rear groove 72 and the second rear cutting edge 71.

  The plurality of second front grooves 62 of the present embodiment are separated from each other over the entire length of the second region 4. Similarly, the plurality of second rear grooves 72 of the present embodiment are separated from each other over the entire length of the second region 4.

  Each of the plurality of second front grooves 62 of the present embodiment extends in a spiral shape. Similarly, all of the plurality of second rear grooves 72 of the present embodiment extend in a spiral shape. The plurality of second front grooves 62 can also be extended in a straight shape. This also applies to the plurality of second rear grooves 72.

  Each of the second front groove 62 and the second rear groove 72 joins the corresponding first groove 32 as shown in FIG. According to such a configuration, chips generated from each of the first cutting edge 31, the second front cutting edge 61, and the second rear cutting edge 71 can be collectively discharged to the rear end 1b side. In addition, the 1st groove | channel 32, the 2nd front groove | channel 62, and the 2nd back groove | channel 72 are not limited to the structure which mutually merges, It is also possible to make it mutually independent.

  As shown in FIG. 1B, the second region 4 of the present embodiment is a second front relief located on the rear side in the rotation direction of the drill 1 with respect to the second front cutting edge 61 in the front stage portion 6. A surface 64 is further provided. Further, the second region 4 of the present embodiment further has a second rear flank 74 that is located on the rear side in the rotational direction of the drill 1 with respect to the second rear cutting edge 71 in the rear stage portion 7. . Both the second front flank 64 and the second rear flank 74 are portions having a role of reducing the cutting resistance by avoiding contact with the work material 100, similarly to the first flank 34 described above. Has a clearance angle. The clearance angles of the second front flank 64 and the second rear flank 74 are preferably 5 to 30 °, but are not limited thereto.

  Here, in this embodiment, as shown in FIG. 3, the first region 3 and the second region 4 described above have the following configuration. That is, the first region 3 has a diameter D that decreases from the end portion 31a located on the outer peripheral portion 20 side of each cutting portion 2 of the plurality of first cutting edges 31 toward the rear end portion 1b side. ing. The second region 4 further includes a front region 8 and a rear region 9 in order from the distal end portion 1a side. The front region 8 is located across the adjacent rear stage portion 7 from the end portion 61a located on the outer peripheral portion 20 side of each of the plurality of second front cutting edges 61. The front region 8 has a diameter D that decreases from the respective end portions 61a of the plurality of second front cutting edges 61 toward the rear end portion 1b. The rear region 9 has a constant diameter D from the end portion 71a located on the outer peripheral portion 20 side of each of the plurality of second rear cutting edges 71 toward the rear end portion 1b side. According to these configurations, the following excellent hole workability can be exhibited.

  That is, in the present embodiment, both the first region 3 and the front region 8 function as regions for roughing. As described above, the first region 3 and the front region 8 both have a diameter D that decreases toward the rear end 1b. Accordingly, both the first region 3 and the front region 8 of the present embodiment have a so-called back taper. According to such a configuration, it is possible to perform roughing of the work material 100 by the first region 3 and the front region 8 while suppressing the bending of the work material 100.

  In the present embodiment, the fact that the diameter D of the first region 3 decreases from the end 31a toward the rear end 1b means the following configuration. That is, the diameter D of the first region 3 is not a configuration that increases from the end portion 31a toward the rear end portion 1b. In addition, the diameter D of the first region 3 is not constant from the end portion 31a to the entire rear end portion 1b side. Therefore, the configuration may be such that the diameter D of the first region 3 always decreases from the end portion 31a toward the rear end portion 1b side, but it may have a portion where the diameter D is constant. .

  Similarly, the fact that the diameter D of the front region 8 becomes smaller toward the rear end portion 1b means the following configuration. That is, the diameter D of the front region 8 is not configured to increase toward the rear end portion 1b. In addition, the diameter D of the front region 8 is not constant throughout the front region 8. For this reason, the diameter D of the front region 8 may be constantly reduced toward the rear end portion 1b, but may have a portion where the diameter D is constant.

  For example, the diameter D of the portion on the front end portion 1a side in the front region 8 becomes smaller toward the rear end portion 1b side, and the diameter D of the portion on the rear end portion 1b side in the front region 8 is constant. May be. The diameter D should just become small as it goes to the rear-end part 1b side so that bending of the workpiece 100 can be suppressed in the part by the side of the front-end | tip part 1a in the front area | region 8.

  Further, the diameter D at a part of the front region 8 that is continuous with the end portion 61a on the front end portion 1a side may be partially constant. As described above, since the diameter D in the portion continuing to the end portion 61a is constant, the second front cutting edge 61 can be stably cut.

  In the present embodiment, the rear area 9 functions as an area for finishing. The rear region 9 does not have a back taper like the first region 3 and the front region 8 because the diameter D is constant toward the rear end 1b side. According to such a configuration, the thrust resistance during cutting becomes appropriate, and the operability of the drill 1 can be improved. Further, it is possible to obtain a burnishing effect in which the inner wall surface of the processed hole is pressed and smoothed by the rear region 9. Occurrence of burrs at the exit of the processed hole can be suppressed. When the work material 100 is a laminate, the occurrence of delamination (delamination) can be suppressed. And the drill 1 of this embodiment can combine the effect by these rear area | regions 9, and the effect by the 1st area | region 3 and the front area | region 8 mentioned above, and can show the outstanding hole workability. Furthermore, since the drill 1 of this embodiment has a relatively simple configuration as described above, it can be easily manufactured.

  As shown in FIG. 2A, the rear region 9 is preferably located from the end portions 71 a of the plurality of second rear cutting edges 71 to at least the terminal ends 721 of the plurality of second rear grooves 72. . The rear region 9 of the present embodiment is located from the end portions 71a of the plurality of second rear cutting edges 71 to the other end portion 4b of the second region 4 located on the rear end portion 1b side. According to such a configuration, chips can be stably passed through the second rear groove 72 and discharged to the rear end 1b side.

  In the present embodiment, the length L9 of the rear region 9 in the direction parallel to the rotation axis S is parallel to the rotation axis S when viewed from the direction perpendicular to the rotation axis S, as shown in FIG. Is greater than both the length L3 of the first region 3 and the length L8 of the front region 8 in the direction. According to such a configuration, a large rear region 9 can be secured in the cutting portion 2, so that the thrust resistance during cutting is moderated to improve the operability of the drill 1, and the safety of the drill user during drill operation is improved. It can be secured.

  In the present embodiment, when viewed from the direction perpendicular to the rotation axis S, the length L3 of the first region 3 and the length L8 of the front region 8 in the direction parallel to the rotation axis S are substantially the same. is there. According to such a configuration, the first region 3 and the front region 8 function in a well-balanced manner, and rough workability can be improved.

  In the present embodiment, the land is located in an area where the first groove 32, the second front groove 62, and the second rear groove 72 are not present in the outer peripheral portion 20 of the cutting portion 2. Specifically, as shown in FIG. 4A, the first region 3 of the present embodiment is located between the first grooves 32 and 32 adjacent to each other among the plurality of first grooves 32 in the outer peripheral portion 20. The plurality of first lands 33 are further provided. As shown in FIG. 4B, the second region 4 of the present embodiment includes a plurality of second front grooves 62 and 62 that are adjacent to each other among the plurality of second front grooves 62 in the outer peripheral portion 20. The second front land 63 is further provided. Further, as shown in FIG. 4C, the second region 4 of the present embodiment is located between the second rear grooves 72, 72 adjacent to each other among the plurality of second rear grooves 72 in the outer peripheral portion 20. And a plurality of second rear lands 73.

  A region where the first land 33, the second front land 63, and the second rear land 73 are partially located in the outer peripheral portion 20 of the cutting portion 2 is formed in the drill 1 with the first groove 32, the second front groove 62, and The size is maintained before the second rear groove 72 is formed. That is, in a cross-sectional view perpendicular to the rotation axis S, all of the first land 33, the second front land 63, and the second rear land 73 are arc-shaped portions corresponding to the outer peripheral portion 20 of the cutting portion 2. It is.

  In a cross-sectional view perpendicular to the rotation axis S, the length L33 of the first land 33 is preferably 3 to 60% with respect to the total length of the outer peripheral portion 20 of the cutting portion 2, and the length of the second front land 63 is L63 is preferably 3 to 60%, and the length L73 of the second rear land 73 is preferably 3 to 60%. In addition, the length of each land is not limited to the illustrated numerical range.

  In the present embodiment, the second rear land 73 among the first land 33, the second front land 63, and the second rear land 73 described above is arranged in order from the front side in the rotation direction of the drill 1 to the margin 731 and the margin 731. And a clearance 732 that is recessed. In other words, each of the plurality of second rear lands 73 of the present embodiment has a margin 731 and a clearance 732 that is recessed with respect to the margin 731 in order from the front side in the rotation direction of the drill 1. . According to such a configuration, since the contact area between the rear region 9 and the work material 100 is reduced, the frictional heat generated in the rear region 9 can be reduced. Therefore, even if the work material 100 includes, for example, an easily burnable carbon-fiber-reinforced plastic (hereinafter sometimes referred to as “CFRP”), Finishing can be performed while suppressing burning.

  In a cross-sectional view perpendicular to the rotation axis S, the length of the margin 731 is preferably 10 to 70% with respect to the entire length of the second rear land 73, and the length of the clearance 732 is 30 to 90%. Is preferred. Note that the lengths of the margin 731 and the clearance 732 are not limited to the illustrated numerical ranges.

  On the other hand, the first land 33 and the second front land 63 of the present embodiment do not have the clearance 732 unlike the second rear land 73. Therefore, in this embodiment, the frictional heat generated in the first region 3 and the front region 8 is higher than the frictional heat generated in the rear region 9. Since the first region 3 and the front region 8 of the present embodiment are regions where roughing is performed as described above, the influence of frictional heat is less than that of the rear region 9 where finishing is performed. In the present embodiment, it is possible to improve the guide performance of the drill 1 in the first region 3 and the front region 8 by bringing each of the first land 33 and the second front land 63 into sliding contact with the inner wall surface of the machining hole. It becomes. This effect is suitable for a hand drill.

  In the present embodiment, the radial rake angles of the plurality of first cutting edges 31 and the plurality of second rear cutting edges 71 are substantially the same. In the present embodiment, the radial rake angles of the plurality of first cutting edges 31, the plurality of second front cutting edges 61, and the plurality of second rear cutting edges 71 are substantially the same. According to these configurations, the cutting performance can be made substantially the same in both the first region 3 and the second region 4, and it is possible to perform drilling while discharging chips stably. Become. In addition, since the configuration of each cutting blade is simplified, the drill 1 can be easily manufactured.

  In the present embodiment, the number of cutting edges in the plurality of first cutting edges 31 and the plurality of second rear cutting edges 71 are the same. Moreover, in this embodiment, the number of each cutting blade in the some 1st cutting blade 31, the some 2nd front cutting edge 61, and the some 2nd rear cutting edge 71 is the same. According to these structures, since the structure of each cutting blade becomes simple, manufacture of the drill 1 can be facilitated.

  The drill 1 of the present embodiment described above further includes a shank portion (not shown) located on the rear end portion 1 b side of the cutting portion 2 and positioned at the base end portion of the drill 1. A shank part is a site | part hold | gripped by the rotating shaft of a machine tool. Examples of the machine tool for gripping the shank portion include a hand drill and a machining center, and a hand drill is particularly preferable.

<Manufacturing method of cut product>
Next, the manufacturing method of the cut workpiece which concerns on embodiment of this invention is demonstrated using FIG.
As shown in FIG. 5A, first, a work material 100 is prepared. Work material 100 is preferably a laminate including a CFRP layer. The laminate may further include a metal layer such as a titanium layer or an aluminum layer. The work material 100 made of such a laminated body is used as a structural member such as an airplane.

  After the work material 100 is prepared, the above-described drill 1 is disposed above the work material 100. Then, the drill 1 is rotated around the rotation axis S in the arrow A direction.

  Next, as shown in FIG. 5B, the drill 1 is fed in the direction of arrow B, and the plurality of first cutting edges 31 and the plurality of second rear cutting edges 71 of the rotating drill 1 are cut into the work material 100. Contact. In the present embodiment, the plurality of second front cutting edges 61 are also brought into contact with the work material 100.

  Then, by further feeding the drill 1 in the direction of arrow B, as shown in FIG. 5C, a through hole 101 that is a processed hole is formed. Since the drill 1 has excellent hole workability for the reasons described above, it is possible to form the through hole 101 having excellent processing accuracy.

  Finally, the desired cut workpiece 110 is obtained by pulling out the drill 1 from the through hole 101 in the direction of arrow C and separating the drill 1 from the work material 100.

  In the case of continuing the cutting process, the plurality of first cutting edges 31 and the plurality of second front cutting edges 61 of the drill 1 are provided at different locations on the work material 100 while maintaining the state in which the drill 1 is rotated. The step of bringing the plurality of second rear cutting edges 71 into contact with each other may be repeated.

  In the present embodiment, the drill 1 is brought close to the work material 100, but the drill 1 and the work material 100 may be made relatively close. For example, the work material 100 may be made close to the drill 1. This also applies to the step of separating the drill 1 from the work material 100.

DESCRIPTION OF SYMBOLS 1 Drill 1a Front-end | tip part 1b Rear-end part 2 Cutting part 20 Outer peripheral part 3 1st area | region 31 1st cutting edge 31a End part 32 1st groove | channel 33 1st land 34 1st flank 35 Catch-in part 4 2nd area | region 4a One end Part 4b other end part 5 step part 6 front part 61 second front cutting edge 61a end part 62 second front groove 63 second front land 64 second front flank 7 rear stage part 71 second rear cutting edge 71a end part 72 second 2 rear groove 721 end 73 second rear land 731 margin 732 clearance 74 second rear flank 8 front region 9 rear region 100 work material 101 through hole 110 work piece S rotating shaft D diameter L3 first region length L8 Length of front area L9 Length of rear area L33 Length of first land L63 Length of second front land L73 Length of second rear land

Claims (11)

A first region located at the tip;
A second region having at least one step portion having a diameter that increases toward the rear end portion side and continuing to the first region at an end portion located on the first region side; Having a substantially cylindrical cutting part extending along the rotation axis,
The at least one step is
A rear stage located on the rear end side ;
A front stage located on the tip side from the rear stage ,
The first region is
A plurality of first cutting edges located at the tip;
A plurality of first grooves extending from the plurality of first cutting edge sides toward the rear end portion side;
Each of the plurality of first cutting edges has a diameter that decreases from the end located on the outer peripheral side of the cutting portion toward the rear end,
The second region is
A plurality of second rear cutting blades located in the rear stage;
A plurality of second rear grooves extending from the plurality of second rear cutting edge sides toward the rear end side;
A rear region having a constant diameter from the end located on the outer peripheral side of each of the plurality of second rear cutting edges toward the rear end,
Have a, a plurality of second front cutting edge located in said front portion,
When viewed from the front, each of the plurality of second front cutting edges and the plurality of second rear cutting edges is shorter than the length of the plurality of first cutting edges, and the plurality of second cutting edges. A drill in which a length of the rear cutting edge is longer than a length of the plurality of second front cutting edges .   2. The drill according to claim 1, wherein the rear region is located from the end portions of the plurality of second rear cutting edges to at least end points of the plurality of second rear grooves. Before Symbol the second region,
A plurality of second front groove before Symbol plurality of second front cutting edge side extends toward the rear end,
A front region having a diameter that decreases from the end located on the outer peripheral side of each of the plurality of second front cutting edges toward the rear end. Drill as described in.   When viewed from a direction perpendicular to the rotation axis, the length of the rear region in the direction parallel to the rotation axis is equal to the length of the first region in the direction parallel to the rotation axis and the length of the front region. 4. A drill according to claim 3, wherein the drill is larger than any of the lengths.   The length of the first region and the length of the front region in a direction parallel to the rotation axis when viewed from a direction perpendicular to the rotation axis are substantially the same as each other. Drill. The second region further includes a plurality of second rear lands located between the second rear grooves adjacent to each other among the plurality of second rear grooves in the outer peripheral portion,
The drill according to any one of claims 1 to 5, wherein each of the plurality of second rear lands has a margin and a clearance recessed with respect to the margin in order from the front side in the rotation direction of the drill. . The first region before Symbol further has a plurality of first lands that are located between the first groove adjacent to each other among the plurality of first grooves in the outer peripheral portion,
Said second region,
A plurality of second front groove before Symbol plurality of second front cutting edge side extends toward the rear end,
The drill according to any one of claims 1 to 6, further comprising: a plurality of second front lands located between adjacent second front grooves among the plurality of second front grooves in the outer peripheral portion. .   The drill according to any one of claims 1 to 7, wherein radial rake angles of the plurality of first cutting edges and the plurality of second rear cutting edges are substantially the same. Before SL plurality of first cutting edges, each of the radial rake angle of the plurality of second front cutting edge and the plurality of second rear cutting edge is substantially the same, according to claim 1 drill. Rotating the drill according to any one of claims 1 to 9 around the rotation axis;
Contacting the work pieces with the plurality of first cutting edges and the plurality of second rear cutting edges of the rotating drill,
And a step of separating the drill from the work material.   The method of manufacturing a cut product according to claim 10, wherein the work material is a laminate including a carbon fiber reinforced plastic layer.

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