CN115135440B - End mill and method for manufacturing cut product - Google Patents

Abstract

The end mill has a body extending along an axis of rotation from a first end to a second end. The main body has: a chisel edge at the first end; a first cutting edge extending from the chisel edge toward the outer periphery; a first relief surface connected to the first cutting edge at a rear side of the rotation direction of the rotation shaft; a first cutter groove connected to the first cutting edge at the front in the rotation direction; and a discharge slot located closer to the second end than the first sipe. The first pocket has a bottom, a first wall surface located between the bottom and the first cutting edge, and a second wall surface located forward in the rotational direction with respect to the bottom. The first wall extends to a position closer to the second end than the second wall.

Description

End mill and method for manufacturing machined product

Cross-reference to related applications

This application claims the benefit of Japanese Patent Application No. 2020-033543 filed on February 28, 2020, and the entire disclosure of the prior application is incorporated herein by reference.

Technical Field

The present disclosure generally relates to a rotary tool used in rotary cutting of a workpiece. As the rotary tool, for example, an end mill can be cited. As the end mill, for example, a square end mill and a ball end mill can be cited.

Background Art

As a cutting tool used when performing rotary cutting processing on a workpiece, for example, a ball end mill described in Japanese Patent Publication No. 2010-105093 (Patent Document 1) can be cited. The ball end mill described in Patent Document 1 is an example of an end mill. The end mill described in Patent Document 1 has a cutting edge, a first center groove portion, a second center groove portion, and a chip discharge groove. The first center groove portion and the second center groove portion are each in the shape of a V-shaped groove.

In Patent Document 1, the first center groove portion and the second center groove portion are V-shaped grooves. Therefore, in a portion away from the cutting edge, there is a possibility that chips cannot pass over the first center groove portion and become clogged in the first center groove portion.

Summary of the invention

An end mill of one aspect of the present disclosure that is not limited has a body extending from a first end to a second end along a rotation axis. The body has: a chisel edge located at the first end; a first cutting edge and a second cutting edge, which extend from the chisel edge toward the periphery, respectively; a first flank surface connected to the first cutting edge at the rear of the rotation direction of the rotation axis; a second flank surface connected to the second cutting edge at the rear of the rotation direction of the rotation axis; a first groove connected to the first cutting edge at the front of the rotation direction; and a discharge groove located closer to the second end than the first groove. The first groove has: a bottom; a first wall surface located between the bottom and the first cutting edge; and a second wall surface located forward of the rotation direction relative to the bottom. The first wall surface extends to a position closer to the second end than the second wall surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an end mill according to a non-limiting embodiment.

FIG. 2 is a plan view of the end mill shown in FIG. 1 as viewed from the first end side.

FIG. 3 is a side view of the end mill shown in FIG. 2 as viewed from the direction A1.

FIG. 4 is a side view of the end mill shown in FIG. 2 as viewed from the direction A2.

FIG. 5 is a side view of the end mill shown in FIG. 2 as viewed from the direction A3.

FIG. 6 is a side view of the end mill shown in FIG. 2 as viewed from the direction A4.

FIG. 7 is an enlarged view of the region B1 shown in FIG. 3 .

FIG. 8 is an enlarged view of the same area as that shown in FIG. 7 .

FIG9 is a cross-sectional view of a section IX of the end mill shown in FIG8 .

FIG. 10 is a cross-sectional view of the end mill shown in FIG. 8 taken along a line X. FIG.

FIG11 is a cross-sectional view of a cross section taken along line XI of the end mill shown in FIG8 .

FIG. 12 is a cross-sectional view of the XII section of the end mill shown in FIG. 8 .

FIG. 13 is an enlarged view of the region B2 shown in FIG. 5 .

FIG. 14 is a schematic diagram showing one step in a method for producing a machined product according to a non-limiting embodiment.

FIG. 15 is a schematic diagram showing one step in a method for producing a machined product according to a non-limited embodiment.

FIG. 16 is a schematic diagram showing one step in a method for producing a machined product according to a non-limiting embodiment.

DETAILED DESCRIPTION

The end mill 1 of the non-limiting embodiment is described in detail using the drawings. It should be noted that in the non-limiting embodiment, a ball end mill is shown as an example of an end mill. However, the end mill is not limited to a ball end mill, and may be a square end mill, for example.

In the following referenced figures, for the sake of convenience, only the main components of the components constituting the unrestricted embodiment are simplified. Therefore, the end mill 1 may have any components not shown in the figures referenced in this specification. In addition, the dimensions of the components in the figures do not accurately show the dimensions of the actual components and the dimensional ratios of the components. These situations are also the same in the manufacturing method of the cut workpiece described later.

1 and the like, the end mill 1 may include a cylindrical body 3 having a rotation axis R1 and extending from a first end 3a to a second end 3b. Generally, the first end 3a is called a "front end" and the second end 3b is called a "rear end".

The end mill 1 in the non-limited example shown in Fig. 1 may also have a rod-shaped body 3 extending from the first end 3a to the second end 3b along the rotation axis R1. When the body 3 is used for cutting a workpiece to manufacture a cut workpiece, it can rotate in the direction of the arrow R2 around the rotation axis R1 as in the non-limited example shown in Fig. 1.

In an unrestricted example shown in FIG1 , the lower left end of the main body 3 may be the first end 3a, and the upper right end may be the second end 3b. In addition, in an unrestricted example shown in FIGS. 3 to 6 , the left end of the main body 3 may be the first end 3a, and the right end may be the second end 3b.

It should be noted that Figs. 3 to 6 are diagrams showing a state in which the end mill 1 shown in Fig. 2 is rotated at a predetermined angle along the rotation direction R2. Fig. 3 is a diagram of the end mill 1 shown in Fig. 2 observed from the A1 direction. Fig. 4 is a diagram of the end mill 1 shown in Fig. 2 observed from the A2 direction. Fig. 4 is a diagram of the end mill 1 shown in Fig. 2 observed from the A3 direction. Fig. 5 is a diagram of the end mill 1 shown in Fig. 2 observed from the A3 direction. Fig. 5 is a diagram of the end mill 1 shown in Fig. 4 observed from the 90° direction. Fig. 6 is a diagram of the end mill 1 shown in Fig. 2 observed from the A4 direction. Fig. 6 is a diagram of the end mill 1 shown in Fig. 2 observed from the A4 direction. Fig. 6 is a diagram of the end mill 1 shown in Fig. 2 observed from the 90° direction relative to Fig. 5.

The main body 3 in the non-limiting example shown in Fig. 1 may also be cylindrical. The cylindrical shape not only refers to a cylinder in a strict sense, but also includes a shape having minute concavities and convexities or curvatures, etc. It should be noted that the shape of the main body 3 is not limited to a cylindrical shape.

The outer diameter D of the main body 3 can be set to, for example, 4 mm to 25 mm. In addition, when the length of the main body 3 in the direction along the rotation axis R1 is set to L, the relationship between L and D can be set to, for example, L=4D to 15D. In this case, the outer diameter of the main body 3 may be constant from the first end 3a side to the second end 3b side, or may vary. For example, the outer diameter of the main body 3 may decrease from the first end 3a side to the second end 3b side.

The body 3 may also include a chisel edge 5 , a first cutting edge 7 , a second cutting edge 9 , a first relief surface 11 , a second relief surface 13 , a first cutting groove 15 , and a first discharge groove 17 .

The chisel edge 5 may be located at the first end 3a of the body 3. The chisel edge 5 may also intersect the rotation axis R1. In other words, when viewed from the front of the first end 3a along the direction of the rotation axis R1, the chisel edge 5 may include the rotation axis R1. It should be noted that the front view from the first end 3a along the direction of the rotation axis R1 is generally also referred to as front end observation.

The first cutting edge 7 and the second cutting edge 9 may be respectively located near the first end 3a, and may respectively extend from the chisel edge 5 toward the periphery. The first cutting edge 7 may be connected to one end of the chisel edge 5, and the second cutting edge 9 may be connected to the other end of the chisel edge 5. The chisel edge 5, the first cutting edge 7, and the second cutting edge 9 may be used to perform cutting processing of a workpiece.

The first cutting edge 7 and the second cutting edge 9 may be located at the intersection of the rake face and the flank face (the first flank face 11 and the second flank face 13). On the other hand, the chisel edge 5 may be located at the intersection of these flank faces 11 and 13. The cutting edge formed by the chisel edge 5, the first cutting edge 7 and the second cutting edge 9 may be a shape that is rotationally symmetrical at 180° with the rotation axis R1 as the center when viewed from the front end.

In the case where the end mill 1 is a ball end mill as shown in an unrestricted example in FIG1 , the first cutting edge 7 and the second cutting edge 9 may also be in a convex curve shape when viewed from the side, as shown in FIG3 etc. It should be noted that, as described above, in the case where the end mill 1 is a square end mill, the first cutting edge 7 and the second cutting edge 9 may also be in a straight line shape extending in a direction orthogonal to the rotation axis R1.

The first flank surface 11 may also be connected to the first cutting edge 7 behind the rotation direction R2 of the rotation axis R1. The first flank surface 11 may be a plane or a curved surface. When the first flank surface 11 is a plane, the first flank surface 11 may be composed of one plane or a plurality of planes.

The second flank face 13 may also be connected to the second cutting edge 9 behind the rotation direction R2 of the rotation axis R1. The second flank face 13 may be a plane or a curved surface, similarly to the first flank face 11. When the second flank face 13 is a plane, the second flank face 13 may be composed of one plane or a plurality of planes.

The first groove 15 may be connected to the first cutting edge 7 in front of the rotation direction R2. That is, the first cutting edge 7 may be located at the intersection of the first flank 11 and the first groove 15. The first groove 15 may have a function of increasing the strength of the first cutting edge 7.

The first slit 15 may also extend from the outer peripheral surface of the body 3 substantially toward the rotation axis R1. In this case, the first slit 15 may also approach the first end 3a as it moves toward the rotation axis R1. As shown in the figure in an unrestricted example, the first slit 15 may be in a V-groove shape and may also have a first bottom 19, a first wall 21, and a second wall 23.

The first wall surface 21 may also be located between the first bottom portion 19 and the first cutting edge 7. Here, the first wall surface 21 may also be connected to the first cutting edge 7 in front of the rotation direction R2. At this time, the first wall surface 21 may also function as the above-mentioned rake face. The second wall surface 23 may also be located in front of the rotation direction R2 relative to the first bottom portion 19. At this time, the second wall surface 23 may also function as a chip breaking wall that bends the chips. It should be noted that, in other words, the first bottom portion 19 may be located between the first wall surface 21 and the second wall surface 23.

When the first slit 15 having a V-shaped shape is observed in a cross section orthogonal to the extending direction of the first slit 15, the first wall surface 21 may be a straight line or a curve. In the same cross section, the second wall surface 23 may be a straight line or a curve. Moreover, in the same cross section, the first bottom 19 may be a concave curve. In this case, cracks due to cutting load are less likely to occur in the first bottom 19, so the durability of the end mill 1 can be improved.

The first sipe 15 in the shape of a V-groove may extend straight, or may extend spirally around the rotation axis R1 as shown in an unrestricted example in FIG. 1 . The torsion angle of the first sipe 15 in the case where the first sipe 15 extends spirally is not limited to a specific value, and may be set to 5° to 60°, for example. In the case where the first sipe 15 extends spirally, the first wall surface 21 and the second wall surface 23 may be curved surfaces, respectively, and respectively represented by straight lines in the above-mentioned cross section.

The first discharge groove 17 may be located closer to the second end 3b than the first sipe 15. The first discharge groove 17 may have the function of sending the chips generated by the first cutting edge 7 toward the second end 3b and discharging the chips to the outside. The first discharge groove 17 extends toward the second end 3b, but does not need to extend to the second end 3b, and may be located away from the second end 3b.

The first discharge groove 17 may extend straight toward the second end 3b, or may extend spirally around the rotation axis R1 as shown in an unrestricted example in FIG1. When the first discharge groove 17 extends spirally, the torsion angle of the first discharge groove 17 is not limited to a specific value, and may be set to 5° to 60°, for example.

The end mill 1 shown in FIG1 is a tool used in clockwise rotation, so the first flute 15 and the first discharge groove 17 are clockwise twisted, but the end mill 1 is not limited to this. For example, even if the tool is used in counterclockwise rotation and the first flute 15 and the first discharge groove 17 are counterclockwise twisted, there is no problem.

As shown in an unrestricted example in FIG. 7 , the first wall surface 21 may extend to a position closer to the second end 3b than the second wall surface 23. In this case, the chips flowing on the first wall surface 21 tend to move toward a portion located in front of the first grooving 15 in the rotation direction R2 in the region of the first wall surface 21 located in front of the second end 3b than the second wall surface 23. Therefore, the chips are not easily clogged in the first grooving 15, and the chip discharge performance is high. As the portion located in front of the first grooving 15 in the rotation direction R2, for example, the first discharge groove 17 and the second grooving 25 described later as shown in an unrestricted example in FIG. 7 can be cited.

Alternatively, the first wall surface 21 may be connected to the first discharge groove 17, and the second wall surface 23 may be separated from the first discharge groove 17. In this case, the chips flowing on the first grooving 15 easily advance toward the first discharge groove 17. In addition, as described later, when the main body 3 has the second grooving 25, the chips flowing on the first grooving 15 easily advance toward the second grooving 25 in addition to the first discharge groove 17.

The second wall surface 23 may have a portion whose width W decreases as it approaches the second end 3b. The second wall surface 23 as a whole may have a structure in which the width W decreases as it approaches the second end 3b. When the width W of the portion of the second wall surface 23 located near the first end 3a, in other words, located near the cutting edge, is relatively large, the chips can be stably bent at the second wall surface 23.

Furthermore, when the second wall surface 23 has a portion whose width W decreases as it approaches the second end 3b, the width W of the portion of the second wall surface 23 located near the second end 3b decreases. Therefore, the chips can be easily passed over the second wall surface 23 while being stably bent. It should be noted that the width W mentioned above may also refer to the width in the radial direction of the rod-shaped main body 3. In addition, the width W may also be evaluated in a cross section orthogonal to the rotation axis R1, as shown in FIG. 9 , for example.

In the portion of the second wall surface 23 where the width W decreases as it approaches the second end 3b, the width W can be continuously decreased. When the width W is continuously decreased and there is no edge at the upper end of the second wall surface 23, the wear of the second wall surface 23 is not easy to develop, and it is not easy to have a chip on the second wall surface 23. Therefore, the end mill 1 can be used stably for a long time.

The first groove 15 may be connected to the second relief surface 13. In this case, the chips generated by the chisel edge 5 and the first cutting edge 7 can stably flow into the first groove 15. Therefore, the chips are less likely to be clogged near the chisel edge 5 and the first cutting edge 7.

At this time, when the first end 3a is viewed from the front, that is, when viewed from the front end, the ridge line L1 where the second flank surface 13 intersects the second wall surface 23 may have a portion that is inclined backward toward the rotation direction R2 as it moves away from the rotation axis R1. In this case, the amount of the first slit 15 located in front of the direction in which the cutting load is applied to the second cutting edge 9 can be reduced, and the wall thickness of the portion located in front of the direction in which the cutting load is applied to the second cutting edge 9 in the body 3 can be ensured to be thick. Therefore, the durability against the cutting load applied to the second cutting edge 9 is high.

The body 3 may also have a second slit 25 in addition to the first slit 15. The second slit 25 may also be connected to the first slit 15 in front of the rotation direction R2 as in an unrestricted example shown in FIG7. Here, the first wall surface 21 may be connected to the second slit 25 at a position closer to the second end 3b than the end portion of the second wall surface 23 on the second end 3b side.

In this case, the chips flowing on the first wall surface 21 tend to move toward the second groove 25 located ahead of the first groove 15 in the rotation direction R2 in the region of the first wall surface 21 located closer to the second end 3 b than the second wall surface 23 .

The first sipe 15 and the second sipe 25 may be portions respectively referred to as center grooves. For example, the first sipe 15 may be positioned as a first center groove, and the second sipe 25 may be positioned as a second center groove.

The second sipe 25 may be in a V-groove shape and may have a second bottom 27, a third wall 29, and a fourth wall 31. Alternatively, as in an unrestricted example shown in FIG. 7 , the third wall 29 may be relatively located at the rear in the rotation direction R2, the fourth wall 31 may be relatively located at the front in the rotation direction R2, and the second bottom 27 may be located between the third wall 29 and the fourth wall 31.

Here, the first wall surface 21 in the first slit 15 may extend to a position closer to the second end 3b than the second wall surface 23, while the third wall surface 29 and the fourth wall surface 31 in the second slit 25 may extend to a position at the same distance from the second end 3b. Since the second slit 25 is located ahead of the first slit 15 in the rotation direction R2, the space for the chips to flow is larger, and the chips are less likely to be clogged in the second slit 25 than in the first slit 15. Therefore, even if the fourth wall surface 31 extends toward the second end 3b to the same extent as the third wall surface 29, the possibility of chip clogging is small, and the chips can be stably bent by the fourth wall surface 31.

It should be noted that the term “same degree” means that the distance from the second end 3 b to the third wall surface 29 is approximately 95% to 105% of the distance from the second end 3 b to the fourth wall surface 31 .

The second cutting edge 9 has an inner end portion 9a connected to the chisel edge 5. When viewed from the front end, an imaginary straight line that is orthogonal to the tangent line of the second cutting edge 9 at the inner end portion 9a and passes through the inner end portion 9a is set as the reference line L3. At this time, the first sipe 15 may be located at a position rearward of the reference line L3 in the rotation direction R2, and the second sipe 25 may intersect the reference line L3.

When the first slit 15 is located behind the reference line L3 in the rotation direction R2, it is possible to ensure that the wall thickness of the main body 3 is thicker in the portion located in front of the direction in which the cutting load is applied to the second cutting edge 9 and in the vicinity of the second cutting edge 9. Therefore, the durability against the cutting load applied to the second cutting edge 9 is high.

Even when the second groove 25 intersects the reference line L3, that is, the second groove 25 is partially located in front of the direction in which the cutting load is applied to the second cutting edge 9, the durability of the second cutting edge 9 is less affected. This is because the second groove 25 is located in front of the rotation direction R2 relative to the first groove 15. On the other hand, when the second groove 25 is partially located in front of the direction in which the cutting load is applied to the second cutting edge 9, a large space for the flow of chips generated by the first cutting edge 7 is ensured. Therefore, the discharge performance of the chips is higher.

The angle at which the first sipe 15 and the second sipe 25 intersect may decrease as the second end 3b is approached. Specifically, in a cross section perpendicular to the rotation axis X1, the angle at which the first sipe 15 and the second sipe 25 intersect is defined as angle θ. This angle θ may increase as the second end 3b is approached.

When the angle θ at which the first grooving 15 and the second grooving 25 intersect at a portion located near the first end 3a of the ridgeline L2 where the first grooving 15 and the second grooving 25 intersect is relatively small, the chips can be stably bent in the first grooving 15. When the angle θ at which the first grooving 15 and the second grooving 25 intersect at a portion located near the second end 3b of the ridgeline L2 where the first grooving 15 and the second grooving 25 intersect is relatively large, the chips can easily pass over the second wall surface 23.

Therefore, when the angle θ at which the first sipes 15 and the second sipes 25 intersect each other decreases as it approaches the second end 3 b , the chips can be stably bent and easily flow toward the second sipes 25 .

The first sipe 15 may also have a portion smoothly connected to the second sipe 25 on the second end 3b side. As shown in an unrestricted example in FIGS. 11 and 12 , the angle θ of the portion located near the second end 3b in the ridge line L2 where the first sipe 15 and the second sipe 25 intersect is 180°, that is, the first sipe 15 may also have a portion smoothly connected to the second sipe 25. In this case, the chips can be made to flow to the second sipe 25 more easily.

The main body 3 may also have a third sipe 33 , a fourth sipe 35 , and a second discharge groove 37 .

The third groove 33 may be connected to the second cutting edge 9 in front of the rotation direction R2. That is, the second cutting edge 9 may be located at a position where the second relief surface 13 and the third groove 33 intersect. The third groove 33 may have a function of increasing the strength of the second cutting edge 9.

The relationship of the third groove 33 to the second cutting edge 9 may be the same as the relationship of the first groove 15 to the first cutting edge 7. That is, the third groove 33 may also have the third bottom 39 as a surface equivalent to the first bottom 19 in the first groove 15, the fifth wall surface 41 as a surface equivalent to the first wall surface 21 in the first groove 15, and the sixth wall surface 43 as a surface equivalent to the second wall surface 23 in the first groove 15.

The fourth groove 35 may be connected to the third groove 33 in front of the rotation direction R2, as in an unrestricted example shown in FIG. 13. The relationship of the fourth groove 35 to the second cutting edge 9 may be the same as the relationship of the second groove 25 to the first cutting edge 7. That is, the fourth groove 35 may have a fourth bottom 45 as a surface corresponding to the second bottom 27 in the second groove 25, a seventh wall surface 47 as a surface corresponding to the third wall surface 29 in the second groove 25, and an eighth wall surface 49 as a surface corresponding to the fourth wall surface 31 in the second groove 25. Here, the sixth wall surface 43 may be connected to the fourth groove 35 at a position of the sixth wall surface 43 closer to the second end 3b than the end portion on the second end 3b side.

As the material of the main body 3, for example, cemented carbide and cermet can be cited. As the composition of cemented carbide, for example, WC-Co, WC-TiC-Co and WC-TiC-TaC-Co can be cited. Here, WC, TiC, TaC are hard particles, and Co is a binding phase. In addition, cermet can also be a sintered composite material formed by compounding metal and ceramic components. Specifically, as cermet, titanium compounds with titanium carbide (TiC) or titanium nitride (TiN) as the main component can be cited.

The surface of the main body 3 can be coated with a film using a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method. Examples of the composition of the film include titanium carbide (TiC), titanium nitride (TiN), titanium carbonitride (TiCN), or aluminum oxide (Al ₂ O ₃ ). The thickness of the film can be set to, for example, 0.3 μm to 20 μm. It should be noted that the preferred range varies depending on the composition of the film.

As mentioned above, although the end mill 1 of several embodiments is illustrated, this invention is not limited to these, Unless it deviates from the summary of this invention, it is a matter of course that arbitrary forms can be adopted.

<Method for manufacturing machined product>

Next, a method for manufacturing a machined product 101 according to an unrestricted embodiment will be described in detail by taking the case of using the end mill 1 according to the unrestricted embodiment described above as an example. The following description will be made with reference to FIGS. 14 to 16 . It should be noted that, in FIGS. 14 to 16 , as an example of a method for manufacturing a machined product 101, a process of drilling a hole on a workpiece 103 is illustrated. In addition, in order to facilitate visual understanding, the machined product 101 and the workpiece 103 are observed in cross-section in FIGS. 14 to 16 .

The method for producing the machined product 101 according to the non-limited embodiment may include the following steps (1) to (3).

(1) The end mill 1 can be rotated in the direction of arrow R2 about the rotation axis R1, and the end mill 1 can be moved toward the workpiece 103 in the direction Y1 (see FIG. 14 ).

This process can be performed, for example, by fixing the workpiece 103 on a workbench of a machine tool equipped with an end mill 1 and bringing the end mill 1 close while rotating. It should be noted that in this process, the workpiece 103 and the end mill 1 can be relatively close, or the workpiece 103 can be brought close to the end mill 1.

(2) By bringing the end mill 1 closer to the workpiece 103, the rotating end mill 1 can be brought into contact with a desired position on the surface of the workpiece 103 to cut the workpiece 103 (see FIG. 15).

In this step, the chisel edge, the first cutting edge, and the second cutting edge can be brought into contact with desired positions on the surface of the workpiece 103 .

(3) The end mill 1 can be separated from the workpiece 103 in the Y2 direction (see FIG. 16 ).

In this process, as in the above-mentioned process (1), it is sufficient to relatively separate the end mill 1 from the workpiece 103, and for example, the workpiece 103 may be separated from the end mill 1. It should be noted that, as cutting processing, for example, in addition to the hole processing shown in FIG. 16, non-through hole processing, groove processing, and milling processing may also be cited.

By going through the above steps, excellent processability can be exhibited.

It should be noted that when performing the cutting process of the workpiece 103 shown above multiple times, for example, when performing multiple cutting processes on one workpiece 103, the process of making the end mill 1 contact different parts of the workpiece 103 can be repeatedly performed while keeping the end mill 1 rotating.

Description of Reference Numerals

1...End mill

3...Main body

3a...First end

3b...Second end

5...Cross Blade

7...First cutting edge

9...Second cutting edge

9a...Inner end

11...First flank surface

13...Second flank

15...First Slot

17...First discharge slot

19...First bottom

21...First wall

23...Second wall

25...Second Slot

27...Second bottom

29...The third wall

31...The fourth wall

33...The third knife groove

35...Fourth Slot

37...Second discharge slot

39...Third bottom

41...The fifth wall

43...The Sixth Wall

45...Fourth bottom

47...The Seventh Wall

49...The Eighth Wall

101...Cutting workpiece

103...Working parts

R1...Rotation axis

R2...Direction of rotation

W...Width

L1...Edge line (second flank surface and second wall surface)

L2...Edgeline (first and second grooves)

L3...Baseline

θ...angle (the angle at which the first groove intersects the second groove).

Claims (8)

1. An end mill, wherein: The end mill has a body extending from a first end to a second end along a rotation axis, The subject has: a chisel edge located at the first end; a first cutting edge and a second cutting edge, each of which extends from the chisel edge toward the periphery; a first flank surface connected to the first cutting edge at the rear of the rotation axis in the rotation direction; a second flank surface connected to the second cutting edge at the rear of the rotation axis in the rotation direction; A first cutting groove connected to the first cutting edge in front of the rotation direction; and a discharge groove located closer to the second end than the first sipe, The first blade groove has: bottom; a first wall surface located between the bottom and the first cutting edge and connected to the discharge groove; and a second wall surface located forward of the bottom in the rotation direction and separated from the discharge groove, The first wall surface extends to a position closer to the second end than the second wall surface. 2. An end mill, wherein: The end mill has a body extending from a first end to a second end along a rotation axis, The subject has: a chisel edge located at the first end; a first cutting edge and a second cutting edge, each of which extends from the chisel edge toward the periphery; a first flank surface connected to the first cutting edge at the rear of the rotation axis in the rotation direction; a second flank surface connected to the second cutting edge at the rear of the rotation axis in the rotation direction; A first cutting groove connected to the first cutting edge in front of the rotation direction; and a discharge groove located closer to the second end than the first slit, The first blade groove has: bottom; a first wall surface located between the bottom and the first cutting edge; and a second wall surface, which is located forward of the bottom in the rotation direction, The first wall surface extends to a position closer to the second end than the second wall surface, When the first end is viewed from the front, a ridgeline where the second clearance surface intersects the second wall surface is inclined rearward in the rotation direction as it moves away from the rotation axis. 3. An end mill, wherein: The end mill has a body extending from a first end to a second end along a rotation axis, The subject has: a chisel edge located at the first end; a first cutting edge and a second cutting edge, each of which extends from the chisel edge toward the periphery; a first flank surface connected to the first cutting edge at the rear of the rotation axis in the rotation direction; a second flank surface connected to the second cutting edge at the rear of the rotation axis in the rotation direction; a first cutting groove connected to the first cutting edge in front of the rotation direction; A second blade groove connected to the first blade groove in front of the rotation direction; and a discharge groove located closer to the second end than the first slit, The first blade groove has: bottom; a first wall surface located between the bottom and the first cutting edge; and a second wall surface, which is located forward of the bottom in the rotation direction, The first wall surface extends to a position closer to the second end than the second wall surface, The first wall surface is connected to the second sipe at a position closer to the second end than an end portion of the second wall surface on the second end side. 4. An end mill, wherein: The end mill has a body extending from a first end to a second end along a rotation axis, The subject has: a chisel edge located at the first end; a first cutting edge and a second cutting edge, each extending from the chisel edge toward the periphery; a first flank surface connected to the first cutting edge at the rear of the rotation axis in the rotation direction; a second flank surface connected to the second cutting edge at the rear of the rotation axis in the rotation direction; a first cutting groove connected to the first cutting edge in front of the rotation direction; A second blade groove connected to the first blade groove in front of the rotation direction; and a discharge groove located closer to the second end than the first slit, The second cutting edge has an inner end connected to the chisel edge, When observing the first end from the main view, An imaginary straight line that is orthogonal to the tangent line of the second cutting edge at the inner end and passes through the inner end is a reference line, The first sipe is located behind the reference line in the rotation direction and has: bottom; a first wall surface located between the bottom and the first cutting edge; and a second wall surface, which is located forward of the bottom in the rotation direction, The first wall surface extends to a position closer to the second end than the second wall surface, The second sipe intersects the reference line. 5. An end mill, wherein: The end mill has a body extending from a first end to a second end along a rotation axis, The subject has: a chisel edge located at the first end; a first cutting edge and a second cutting edge, each extending from the chisel edge toward the periphery; a first flank surface connected to the first cutting edge at the rear of the rotation axis in the rotation direction; a second flank surface connected to the second cutting edge at the rear of the rotation axis in the rotation direction; a first cutting groove connected to the first cutting edge in front of the rotation direction; A second blade groove connected to the first blade groove in front of the rotation direction; and a discharge groove located closer to the second end than the first slit, The first blade groove has: bottom; a first wall surface located between the bottom and the first cutting edge; and a second wall surface, which is located forward of the bottom in the rotation direction, The first wall surface extends to a position closer to the second end than the second wall surface, The intersection angle between the first sipe and the second sipe increases as approaching the second end. 6. The end mill according to claim 5, wherein: The first sipe has a portion smoothly connected to the second sipe on the second end side. 7. The end mill according to any one of claims 1 to 6, wherein: The width of the second wall surface decreases as it approaches the second end. 8. A method for manufacturing a machined product, wherein: The method for manufacturing the machined product comprises: A step of rotating the end mill according to any one of claims 1 to 7; a step of bringing the rotating end mill into contact with a workpiece; and A step of separating the end mill from the workpiece.